COVID-19 Data Dispatch

Tag: SARS-CoV-2 variants

  • Omicron updates: The continued importance of vaccination

    Omicron updates: The continued importance of vaccination

    COVID-19 deaths during the Omicron wave have been much higher in the U.S. than in other similarly wealthy countries, according to a New York Times analysis.

    Just a few updates for this week:

    • Scientists are still learning about BA.2, the more-transmissible Omicron offshoot. There haven’t been many major updates about BA.2 since last week, when I wrote this FAQ post; but this STAT News article by Andrew Joseph provides a helpful summary of what we know so far. The article explains that BA.2 clearly has a transmission advantage over BA.1 (and has now become the dominant variant in a few countries), but BA.1 may have spread around the world due to chance and some well-placed superspreading events. Notably, the CDC is not yet splitting out its Omicron prevalence estimates into BA.1 and BA.2, so we don’t have a great sense of how much this sub-lineage is spreading in the U.S.
    • More data indicates immune system memory remains strong against Omicron. In previous Omicron update posts, I’ve noted that, while vaccinated people are more likely to have a breakthrough case with Omicron than with past variants, vaccination is still highly protective against severe symptoms. A new study published in Nature this week further affirms this protection; researchers found that 70% to 80% of T cell response to Omicron was retained in people who were vaccinated or tested positive on antibody tests, compared to past variants. (T cells are key pieces of immune system memory response.)
    • Similarly, more data backs up the importance of vaccination to protect against severe disease during the Omicron era. The CDC released more MMWR studies this week showing that fully vaccinated and boosted Americans were less likely to require hospitalization or intensive care during the Omicron surge compared to the unvaccinated. For example, in Los Angeles County, California, hospitalization rates among unvaccinated people were 23 times higher than rates among those fully vaccinated with a booster, and five times higher than those vaccinated without a booster.

    • Omicron is too transmissible for school testing programs to keep up. I’ve previously reported on the challenges of K-12 COVID-19 testing programs, including the difficulty of setting up public health logistics, getting enough tests, and increasing polarization of testing. During the Omicron surge, these challenges have been magnified—to the point that some states, including Utah, Vermont, and Massachusetts, have suspended testing programs, POLITICO reported this week. I hope to see some of these programs resume after the surge is over.
    • The U.S.’s death toll during the Omicron surge has been far higher than in similarly wealthy nations. A new analysis from the New York Times compares the death toll in the U.S. from December 2021 through January 2022, adjusted for population, to death tolls in peer wealthy nations like Germany, Canada, Australia, and Japan. The comparison is striking: “the share of Americans who have been killed by the coronavirus is at least 63 percent higher than in any of these other large, wealthy nations,” the NYT reports. This difference is largely because the U.S. is less vaccinated than these other countries, particularly when it comes to booster shots and vaccinations among seniors.
    • Globally, cases during the Omicron surge surpassed all of 2020. “In the 10 weeks since Omicron was discovered, there have been 90 million COVID-19 cases reported — more than in all of 2020,” said Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization, at a press conference last week. In a Twitter thread reporting from the press conference, STAT’s Helen Branswell noted that the WHO is concerned about countries “opening up” and lifting COVID-19 restrictions before their case numbers are actually low enough to warrant these measures.

    More variant reporting

  • Other Omicron updates: Healthcare system, treatments, and more

    Other Omicron updates: Healthcare system, treatments, and more

    A new CDC analysis found that Omicron led to record hospitalizations, but lower levels of ICU admissions and other indicators of the most severe disease compared to past surges. Chart via CDC MMWR.

    While BA.2 has dominated the news cycle this week, we’re still learning more about—and seeing policy shifts due to—the original Omicron strain, BA.1. Here are a few major updates:

    • Omicron is causing 100% of new COVID-19 cases in the U.S. According to the CDC’s latest update of its variant prevalence estimates, Omicron caused more than 99% of new COVID-19 cases in the country for the second week in a row: there was a slight increase from 99.4% of new cases in the week ending January 15 to 99.9% in the week ending January 22. The remaining 0.1% of cases are caused by Delta. The CDC is not yet distinguishing between BA.1 and BA.2 in its estimates, but will likely start doing so in the coming weeks.
    • ICU admissions and other indicators of severe COVID-19 symptoms were lower during the Omicron surge than during previous surges in the U.S. The CDC released another round of studies presenting Omicron’s impact on the healthcare system last week, including this report focusing on disease severity. CDC researchers analyzed data from three hospital surveillance systems and an additional large database; while the peak of new COVID-19 cases was five times higher during the Omicron surge than the Delta surge, they found, the peak of hospital admissions was only 1.8 times higher. And ICU admissions, the average stay length for hospitalized COVID-19 patients, and death rates were all lower during the Omicron surge than in the Delta and winter 2020-2021 surges.
    • Pfizer and BioNTech have started a clinical trial of an Omicron-specific vaccine. Quickly after Omicron was identified, both Pfizer and Moderna started updating their vaccines for this variant and investigating whether such Omicron-specific shots would be necessary. Pfizer is now entering a new clinical trial with its Omicron-specific shot, along with its vaccine development partner BioNTech, according to Reuters. Trial participants will include about 1,400 people who received third doses from Pfizer’s current COVID-19 vaccine regimen three to six months earlier. Pfizer intends to study the Omicron-specific shot’s safety and effectiveness against this variant.

    • The FDA recommends that U.S. facilities stop using monoclonal antibody treatments that don’t work well against Omicron. Speaking of Omicron-specific drugs: the Food and Drug Administration (FDA) announced this week that the agency is limiting use of two monoclonal antibody treatments, made by Regeneron and Eli Lilly. Both treatments, which boost patients’ immune systems by providing them with lab-made antibodies, worked well at reducing severe symptoms for past variants but have less of an impact on Omicron infections. As a result, healthcare providers should “ limit their use to only when the patient is likely to have been infected with or exposed to a variant that is susceptible to these treatments,” the FDA says. A third monoclonal antibody treatment, along with other drugs (including Pfizer’s hard-to-find pill), do work well against Omicron.
    • Omicron has a short incubation period, so test timing is key. As I’ve written in the past, Omicron infections tend to move more quickly than infections with past variants: people can go from an exposure to symptoms within three days, rather than four or five. As a result, there’s less time to catch an infection before becoming contagious; but at the same time, rapid tests may give negative results in those early days of an infection, before patients have built up enough of a viral load for an antigen test to identify the infection. A recent New York Times article summarizes the science on how Omicron infections compare to past variants and provides recommendations on testing. For instance: “many experts now recommend taking a rapid test two to four days after a potential exposure,” and ideally testing twice about a day apart.
    • Some experts are optimistic that we could see a COVID-19 lull after Omicron surges. Last week, I shared a STAT News article explaining that, thanks to high levels of population immunity, the U.S. might have “a bit of a break from the Covid roller coaster” after our Omicron surge ends in the coming weeks. Despite BA.2 concerns, Dr. Hans Henri Kluge, WHO’s regional director for Europe, shared a similarly optimistic view in a statement last week. “The pandemic is far from over, but I am hopeful we can end the emergency phase in 2022 and address other health threats that urgently require our attention,” he said.

    More variant reporting

  • BA.2 FAQ: What you should know about this Omicron offshoot

    BA.2 FAQ: What you should know about this Omicron offshoot

    BA.2 has become the dominant strain in Denmark, one of the countries that sounded the alarm about this Omicron offshoot. Chart via the Pandemic Prevention Institute, posted on Twitter on January 26.

    An offshoot strain of the Omicron variant has been making headlines this week as it spreads rapidly in some European and Asian countries. While the strain, called BA.2 by virologists, has not yet been identified in the U.S. in large numbers, it’s already spreading here, too: scientists have picked it up in wastewater samples in some parts of the country.

    This strain clearly has a growth advantage over the original Omicron strain (also called BA.1), but it’s not cause for major concern at this point. Scientists are working to identify whether BA.2 has a higher capacity for breaking through immunity from past infection or vaccination; so far, early data suggest that it does not significantly differ from BA.1 on this front, though it may have a slight advantage.

    Here’s a brief FAQ on what we know about the strain so far.

    When and where did BA.2 emerge?

    I’ve been careful not to call BA.2 a “new strain” or a “new variant” here because it’s not actually new—at least, it’s not any newer than Omicron BA.1. When South African scientists first sounded the alarm about Omicron in late November 2021, BA.2 was already present among the country’s cases of this variant.

    In fact, a paper from South African scientists describing the Omicron wave in their country, published in Nature in early January, specifies that the earliest specimen of BA.2 was sampled on November 17; the earliest specimen of BA.1 was sampled on November 8. Around the same time, South African scientists also identified a third lineage, called BA.3—this one hasn’t yet become a cause for concern.

    Why are scientists concerned about BA.2?

    In the past couple of weeks, epidemiologists have identified that BA.2 is spreading faster in some countries than BA.1, the original Omicron strain. This means BA.2 has what scientists call a “transmission advantage” over BA.1: it is capable of getting from person to person fast enough that it may be able to outcompete BA.1.

    For example, in Denmark, BA.2 became the dominant strain in mid-January, taking over from BA.1. The takeover has coincided with an additional increase in COVID-19 cases in the country after Denmark’s Omicron wave initially appeared to peak a couple of weeks ago—but it’s hard to determine whether this second increase is solely due to BA.2 or also connected to an announcement that Denmark will end its COVID-19 restrictions on February 1.

    This past week, the World Health Organization (WHO) announced that investigations into BA.2, including its potential virulence and ability to escape prior immunity, “should be prioritized independently (and comparatively) to BA.1.” The WHO has yet to designate BA.2 as a separate variant of concern from BA.1, however; at the moment, both strains are still included under the Omicron label.

    https://twitter.com/PeacockFlu/status/1483770131419443201

    How does BA.2 compare to BA.1, the original Omicron strain?

    As I’ve explained in previous posts about the variant, Omicron has the most antigenic drift of any coronavirus variant identified thus far—meaning that it’s the most genetically different from the initial Wuhan version of the virus. Omicron BA.1 has about 60 mutations compared to the Wuhan strain, but BA.2 has even more: about 85 mutations, according to a recent Your Epidemiologist post.

    BA.2 is clearly more transmissible than BA.1, as we’ve seen from its rapid spread in countries including Denmark, the U.K., France, the Netherlands, India, and the Philippines. Scientists estimate that “BA.2 may be 30% to 35% more transmissible than BA.1,” STAT News reports.

    The question scientists hope to answer, then, is why BA.2 has this transmission advantage over BA.1. Do BA.2’s additional mutations lend it some adaptation in how it interacts with human cells, enabling faster spread? Or is BA.2 more capable of evading protection from past infection or vaccination compared to BA.1, leading it to cause more reinfections and breakthrough cases?

    While we don’t know the answers to these questions yet, early data are indicating that there’s no major difference in disease severity between BA.1 and BA.2. In other words, BA.2 isn’t more likely to cause severe symptoms.

    “There is no evidence that the BA.2 variant causes more disease, but it must be more contagious,” Danish Health Minister Magnus Heunicke said at a news conference last week, Reuters reported.

    Why do some articles call BA.2 a “stealth variant?”

    You might have seen some headlines referring to BA.2 as a “stealth variant” or a “stealth version of Omicron.” This is because of one major difference between BA.2 and BA.1: while BA.1 can be identified with a PCR test due to a key mutation that’s visible on PCR test results, BA.2 does not have this mutation.

    As a result, BA.2 can be more time-consuming for COVID-19 testing labs to identify: labs need to sequence a sample’s genome to identify this strain rather than simply look out for an indicator on a PCR test. It’s unclear how much of a difference this will make in the U.S.’s ability to track BA.2, however, as many labs across the country are already performing routine full-genome sequencing of coronavirus samples.

    How well do vaccines work against BA.2?

    So far, it seems like there is no significant difference in vaccine protection between BA.1 and BA.2, at least when it comes to severe symptoms—which makes sense, scientists say, given how well vaccines have worked against every major variant to emerge thus far.

    Early findings in this area come from the U.K., which designated BA.2 as a “Variant Under Investigation” (separate from BA.1) about a week and a half ago. This past Friday, the U.K.’s Health Security Agency released a report with information on BA.2, including how it compares to BA.1 or original Omicron.

    Overall, U.K. epidemiologist Meaghan Kall wrote in a Twitter thread summarizing the report, early evidence suggests that “BA.2 is no more immune evasive than Omicron,” though confidence in this statement is low. The report found that, for Brits who had received booster shots, vaccine effectiveness against symptomatic COVID-19 disease was 70% for BA.2 and 63% for BA.1. The confidence intervals on these effectiveness estimates overlapped, indicating that vaccines perform similarly against BA.2 and BA.1.

    When it comes to disease severity, Kall wrote, the U.K. doesn’t have enough data to compare BA.2 and BA.1; early data on this topic (suggesting BA.2 is not more severe) have come from Denmark and India.

    How will BA.2 impact the U.S.’s COVID-19 trajectory?

    BA.2 has already outcompeted BA.1 in some parts of Europe and Asia, and epidemiologists expect that countries like the U.K. and the U.S. could also follow this pattern—though it will likely be a longer, slower replacement process compared to the intense way Omicron pushed out Delta. A bigger unknown here is what effect this strain may have on case numbers, hospitalizations, and deaths.

    Countries and regions now passing the peaks of their Omicron BA.1 waves have extremely high levels of population immunity. As a result, people who are fully vaccinated with boosters and/or recently infected with Omicron BA.1 likely will have a lot of immune system protection against BA.2, though we don’t yet have good data on exactly how robust this protection is.

    So, could BA.2 cause the current downturn in U.S. COVID-19 cases to reverse? It’s possible, explains Andrew Joseph in a recent STAT News article. However, thanks to our high immunity levels, a further spike in cases could be “broadly limited to infections” rather than causing major increases in hospitalizations and deaths. In the coming weeks, we’ll get a better sense of how well prior Omicron infections protect against BA.2 and other key information that will inform our understanding of how this strain may change the country’s COVID-19 trajectory.

    Right now, COVID-19 experts are closely monitoring BA.2, but they’re not hugely concerned. As Dr. Jetelina put it in a recent Your Local Epidemiologist post, the bigger worry right now is that another variant could “pop out of nowhere” like Omicron did in November.

    More variant reporting

  • Omicron updates: Where will these massive case numbers leave us?

    Omicron updates: Where will these massive case numbers leave us?

    Omicron went from 1% of U.S. cases to nearly 100% of cases in about six weeks. Chart via the CDC, retrieved January 23.

    Major news items for this week include the potential peak of the U.S.’s Omicron surge and real-world data from the CDC on how well booster shots work against this variant.

    • Omicron is now causing nearly 100% of new COVID-19 cases in the U.S. The latest CDC estimates of variant prevalence put Omicron at 99.5% of new cases in the U.S. as of January 15, with Delta causing the remaining 0.5% of cases. I have to say, it’s incredibly striking not only how quickly Omicron outcompeted Delta (it went from 1% of new cases to nearly 100% in just six weeks), but also how both of these highly contagious variants have dominated the country so thoroughly that they’re now the only two variants present here at all. For comparison, Alpha only got to 70% of cases at its peak. These trends show how drastically both Delta and Omicron changed the trajectory of the pandemic.
    • While the U.S. may be peaking, massive numbers of people are getting infected. As I noted in today’s National Numbers, America’s Omicron wave may have peaked this week, with the country’s massive case growth appearing to turn around. Computational biologist Trevor Bedford wrote a recent Twitter thread about this peak, pointing out that a huge share of the U.S. population was infected with Omicron in the past month: “between 18% and 23% of the country was infected by Omicron by Jan 17, with the large majority infected in a span of just ~4 weeks,” he hypothesized. By mid-February, Bedford says, this number could be “36%-46%.”

    • The high infection numbers may give us “a bit of a break from the Covid roller coaster.” With so many people infected in such a short time, Omicron will have a huge impact on the “immunological landscape” of the U.S, Helen Branswell explains in a recent article for STAT News. Millions will have immunity from a recent infection, vaccination, or both; and Omicron’s unique biology may mean that people who caught this variant will be protected from other strains. As a result, the end of this wave may lead into “a bit of a break” from COVID-19, Branswell writes, with low case numbers for a few weeks or months. It’s hard to say whether this “break” will constitute the end of the pandemic, though—we don’t know how long post-Omicron immunity lasts.
    • Rapid at-home tests work well at detecting Omicron, though they’re far from perfect. As I’ve noted in past issues, there have been some questions recently about how well rapid antigen tests work at identifying Omicron infections. In a recent Your Local Epidemiologist post, Dr. Katelyn Jetelina walked through the data from several recent studies on this topic. The highlights: rapid tests likely won’t work well in the very beginning of an infection, so wait to test until five days after an exposure; if you test positive, trust the result; test repeatedly for higher accuracy; and, if you have the tests, wait for two negative results before coming out of isolation.
    • New CDC wastewater report shows how early Omicron was spreading in the U.S. The CDC published a report this week sharing findings from wastewater surveillance systems in a few states and localities. (Wastewater surveillance means the states are regularly testing samples from sewage to identify coronavirus levels coming from residents’, well, waste.) In New York City, Omicron was first detected in wastewater on November 21, the weekend before Thanksgiving. In California, Colorado, and Houston, Texas, the variant was detected in late November or early December.
    • An additional booster shot may not be enough to completely prevent Omicron infection, a small Israeli study suggests. Israel was one of the first countries to offer third vaccine doses to its residents, and now it’s also one of the first countries offering fourth doses. A new study presents the impact of these shots among about 270 healthcare workers. The additional doses produced more antibodies in the patients, but “this is probably not enough for the Omicron,” one of the study’s authors told Reuters—at least when it comes to completely preventing infection.
    • But: booster shots still reduce chances of infection significantly, compared to people who are unvaccinated. Another new CDC report published this week compares COVID-19 cases among vaccinated, boosted, and unvaccinated people in 25 U.S. jurisdictions. In late December, after Omicron started spreading widely, adults who were unvaccinated had a five times higher risk of COVID-19 infection compared to those who were fully vaccinated with a booster shot, the CDC found.
    • Booster shots also have a huge impact on risks of severe symptoms and hospitalization. One more CDC report released this week: scientists analyzed the impact of booster shots on emergency department visits and other hospitalization metrics in ten states. When both Delta and Omicron were the dominant variants in the U.S., the CDC researchers found, third doses had 94% efficacy rates in protecting people against COVID-related emergency department visits, and 82% efficacy rates in protecting against urgent care visits. Efficacy against hospitalization was also over 90%. In short: if you’re eligible for your booster, go get it!
    • Booster shots of Pfizer and Moderna vaccines could be critical for countries that used other brands. Last week, I shared a report that found 22 million mRNA vaccine doses are needed as booster shots in low-income countries, to protect the world against Omicron. This past week, a new study in Nature supported this report: a group of scientists in Hong Kong found that Pfizer doses are safe and highly effective booster shots for people who initially received the Chinese CoronaVac vaccine. The authors suggest that mRNA vaccines should be used as boosters in countries that originally distributed CoronaVac.
    • New research identifies a mutation that may contribute to Omicron’s super-contagiousness. A new study from the National Institutes of Health (NIH) found that a mutation present in the Alpha and Delta variants allows the coronavirus to more easily bind to human cells. When the coronavirus binds more easily, it can spread faster within the body; this rapid multiplication helps the virus quickly spread outside the body as well, increasing contagiousness. Though this study was done before the Omicron variant emerged, Omicron has this same mutation, explained lead author Dr. Lawrence Tabak in a post for the NIH Director’s Blog.

    More variant reporting

  • Omicron updates: Possible peaks, viral loads, vaccines

    Omicron updates: Possible peaks, viral loads, vaccines

    Has Omicron peaked in NYC? It sure seems like it, according to city data; screenshot retrieved from NYC Health dashboard on January 16.

    These update posts are getting shorter as time goes on, but we’re still learning about this variant! A few news items from this week:

    • Omicron is now causing almost 100% of new COVID-19 cases in the U.S. In the CDC’s latest variant proportions update, the agency estimated that 98% of new COVID-19 cases were caused by Omicron in the week ending January 8. The CDC also revised estimates for previous weeks, though the revisions were not as significant as they have been in the past—suggesting that the numbers are now fairly close to accurate, but will continue to be tweaked as more sequencing data come in.
    • Major Northeast hotspots appear to be peaking. Last week, I wrote that New York City’s Omicron wave seemed to have reached its peak. The trend has continued into this week: the new case rate and test positivity rate have both fallen consistently since peaking on January 3. Similarly, in Boston, the Omicron levels detected in the city’s wastewater have declined steeply since early January. The daily case rate is also going down in Washington, D.C., and in the Northeast region overall. Still, hospitals are still overwhelmed throughout the region, and it’s unlikely that cases will go down as quickly or as decisively as they went up.

    • New NYC report provides data on the city’s Omicron wave. Speaking of NYC: the city’s public health department recently put out a new report detailing the variant’s impact. The variant “has accounted for nearly all coronavirus samples sequenced in NYC” since Christmas, the report’s authors write. Also, while a smaller share of Omicron cases led to hospitalization compared to the Delta wave, more people have been hospitalized overall because of sheer case numbers. Unvaccinated New Yorkers, Black New Yorkers, and those over age 75 have been most likely to require hospitalization.
    • Real-world study suggests rapid at-home tests work well at detecting Omicron. A new study from the University of California, San Francisco, released this week as a preprint, analyzed rapid antigen tests’ capacity to detect Omicron by comparing rapid test results to PCR test results. The results: antigen tests correctly identified 95% of cases with high viral loads and 98% of symptomatic cases. In about one-third of the cases identified through PCR, patients tested negative on antigen tests; but this is in line with the tests’ accuracy for other variants.
    • Data from the NBA suggest Omicron’s viral load is pretty variable. Another new study posted as a preprint this week analyzed data from the National Basketball Association (NBA). The league’s regular testing policy allowed Harvard researchers to study viral loads in Omicron-positive patients, revealing that this variant had “lower peak viral load and more variable early viral growth durations than Delta,” according to one of the authors. In other words, some of the basketball players were highly contagious early into their Omicron infections, while others were less so; and the players had less virus in their bodies overall at the peak of their infections than in previous Delta infections. Also, a large number of the players were still contagious five days after they were diagnosed—which doesn’t bode well for the CDC’s new isolation guidance.
    • More confirmation that vaccinated people are protected from severe disease from Omicron. Another new study, this one published in Nature through the journal’s advance preview system for COVID-19 reports, confirms previous research about T cell response to Omicron. T cells are a key part of the immune system’s long-term memory apparatus; they help protect against severe symptoms and death. The study found that, in patients who were fully vaccinated (or, to a lesser degree, had a previous infection), T cells could recognize Omicron and protect people against its worst impacts.
    • Omicron adds urgency to the need to vaccinate the world—ideally, with mRNA vaccines. A report from advocacy groups PrEP4All and Partners In Health, written with scientists at Harvard, Columbia, and other institutions, found that 22 billion additional mRNA vaccine doses are needed to control the pandemic, now that Omicron has become the dominant variant in the world. The report specifies that mRNA vaccines are needed because other vaccine types are not capable of preventing Omicron infection, and likely are less effective against severe disease. “Future viral variants may become even more transmissible, immune evasive, and virulent than Delta or Omicron,” the report cautions.

    More variant reporting

  • Six more things, January 9

    Six more things, January 9

    If you test positive for COVID-19, here’s what the CDC says you should do. Graphic via the Maine health agency.

    Here are six other COVID-19 news items from the past week that didn’t quite warrant full posts:

    • The CDC made its COVID-19 isolation guidance even more confusing, somehow. On Tuesday, the CDC updated its isolation guidance again—and the new guidance is, kind-of a “dumpster fire,” as the headline on this article by The Atlantic’s Katherine J. Wu aptly puts it. The agency still isn’t requiring rapid tests to get out of isolation early, but it says you can test if you have one available. Also, wear a mask if you leave isolation after five days and avoid travel, restaurants, and other high-exposure activities. Wu’s article provides a good summary of the guidance (and criticism of that guidance), as does this Your Local Epidemiologist post from Dr. Katelyn Jetelina.
    • New reporting recipe explains how to explore “uncounted” COVID-19 deaths with CDC data. Last week, I shared a new investigative story from my team at the Documenting COVID-19 project that dives into unreported COVID-19 deaths in the U.S. Up to 200,000 deaths may have gone unrecorded thanks to a lack of training, standardization, tests, and other issues with death reporting. This week, the team published a reporting recipe aimed to help other journalists do similar stories in their states, cities, and regions. If you have questions about the project or recipe, you can reach out to us at info@documentingcovid19.io.
    • B.1.640.2, or the “IHU variant” from France, is not currently cause for concern. In the past few days, you might have seen headlines about a new variant called B.1.640.2 that was identified in France last November. The variant has a number of mutations, including some mutations that have also been identified in other highly-contagious variants, according to a recent preprint from French researchers. But it’s not currently a concern, say experts at the World Health Organization and elsewhere. This variant actually predates Omicron, and only 20 cases had been reported between early November and early January (compared to well over 100,000 Omicron cases in the same timespan). Omicron is the main variant we should be worrying about right now.
    https://twitter.com/sailorrooscout/status/1478130286072410118
    • “Flurona” means getting the flu and COVID-19 at the same time; it’s not a new mutant disease. Another buzzword you might’ve seen in headlines this week: “flurona,” a portmanteau of coronavirus and flu. Los Angeles and other places have recently reported cases in which a patient tests positive for both the flu and COVID-19 at the same time. While having two respiratory diseases at once is certainly unpleasant—and might lead to increased risk of severe symptoms—it’s not necessarily worth freaking out over. Roxanne Khamsi covered these potential coinfections in The Atlantic back in November 2021, writing: “Recent screening studies have found that 14 to 70 percent of those hospitalized with flu-like illness test positive for more than one viral pathogen.”
    • Senators call for HHS to answer key questions about COVID-19 testing. This week, Senators Roy Blunt (Missouri) and Richard Burr (North Carolina) wrote to Health and Human Services (HHS) Secretary Xavier Becerra requesting information on COVID-19 test spending. The Senators note that over $82.6 billion has been “specifically appropriated for testing,” yet the U.S. continues to experience dire shortages and delays for both PCR and rapid tests. The letter includes questions about Biden’s initiative to distribute 500 million rapid tests for free; little information has been shared about the initiative so far.
    • New meta-analysis estimates one in three COVID-19 patients have persistent symptoms for 12 weeks or more. In a meta-analysis, scientists compile results from a number of studies on the same topic in order to provide overall estimates for an important metric, like the risk of developing a particular condition. A new analysis from researchers at a Toronto hospital network and other co-authors examined the risk of Long COVID symptoms following a COVID-19 diagnosis, combining results from 81 studies. Their main findings: about 32% of patients had fatigue 12 weeks after their diagnosis, while 22% had cognitive impairment at 12 weeks; and the majority of those patients still had these symptoms at six months. (H/t Hannah Davis.)

    Note: this title and format are inspired by Rob Meyer’s Weekly Planet newsletter.

  • Omicron updates: the surge is here, but peaks might be in sight

    Omicron updates: the surge is here, but peaks might be in sight

    Antigenic drift posed by Omicron. Figure from Sanders et al., posted to Medrxiv on January 3.

    As the Omicron surge continues, we are still learning more about this variant. Here are the major updates from this week:

    • Omicron is now causing more than 90% of new cases in the U.S. In the latest update of the CDC’s variant proportions estimates, the agency found that Omicron caused 95% of new COVID-19 cases nationwide in the week ending January 1. The CDC also revised estimates for previous weeks, bringing us to 77% Omicron for the week ending December 25 and 38% Omicron for the week ending December 18. While these estimates continue to be based on weeks-old data, it the CDC now has enough sequencing information to make Omicron estimates with lower confidence intervals than it did a few weeks ago—suggesting that these numbers are closer to reality than the estimates we saw in December.
    https://twitter.com/jaspar/status/1478773556435730432

    • Omicron is causing the vast majority of cases in every state. Also included in the CDC’s variant proportions estimates: regional numbers. The latest figures estimate that, as of January 1, Omicron prevalence across the country ranges from 82% in the Northeast to 98% in New York/New Jersey and the Gulf states region (Texas, Louisiana, Arkansas, Oklahoma, and New Mexico). These numbers align with recent calculations from computational biologist Trevor Bedford based on sequences posed to the public repository GISAID. In short: Omicron is everywhere.
    • Evidence that Omicron is less likely to cause severe symptoms continues to mount. A combination of real-world hospitalization and lab data continue to suggest that Omicron is less likely to cause severe COVID-19 symptoms than past coronavirus variants. The hospitalization data: in Omicron hotspots, hospitalization numbers are not rising at the same rate as case numbers, nor are the numbers of patients who require intensive care or ventilators. “Despite steep rises in cases and patients, the number on ventilators has barely risen,” wrote Financial Times data journalist John Burn-Murdoch in a recent thread about U.K. data.
    • And the lab data: a growing number of studies show that Omicron is less capable of infecting patients’ lungs compared to past variants—meaning the worst respiratory symptoms are rarer. At the same time, people who catch Omicron after gaining immunity from vaccination and/or prior infection are protected against severe symptoms thanks to T cells and other aspects of immune system memory. Note that, however, we still don’t know about the risk of Long COVID following an Omicron case.
    • Still: U.S. Hospitals are now incredibly overwhelmed with Omicron and Delta cases. In the U.S. so far, the “decoupling” phenomenon (in which hospitalizations and ICU admissions don’t rise as fast as cases) has been less visible than in other countries hit by Omicron. Several states have already set hospitalization and/or ICU records during the Omicron surge. This is likely because many parts of the U.S. have lower vaccination rates than other countries like the U.K. At the same time, accounts from hospital workers show the toll that this surge is taking: “Thankfully the Covid patients aren’t as sick. BUT there’s SO many of them,” wrote NYC ER doctor Dr. Craig Spencer in a recent Twitter thread.

    • Omicron has more antigenic drift than any other variant. “Antigenic drift” is a virology term referring to the small mutations in virus genetic material that cause these viruses to change slowly over time. As I noted in early Omicron updates, this variant didn’t evolve out of Delta (as many experts were expecting) but rather showed up seemingly out of nowhere; it might have emerged from a part of the world with limited variant surveillance, an immunocompromised person, or even an animal host. We don’t know Omicron’s origin yet, but we now know that it is further apart, genetically speaking, from the original coronavirus than any other variant so far.
    • London’s Omicron surge may have peaked. According to U.K. data, both case numbers and hospital admission numbers have slowed in their increases, the Washington Post reports. “For the moment, we can probably say London appears to be over the worst,” U.K. hospital executive Chris Hopson said last week. Other U.K. health officials are more skeptical though, according to the Post: while case numbers are falling for teenagers and younger adults, London is still reporting increasing cases among seniors.
    • New York City also might be on the verge of peaking. Another tentative peak report: data from NYC’s health department suggest that case numbers might be starting to fall in the city. The citywide seven-day average for new cases fell from 3,261 per 100,000 people on January 2 to 2,754 per 100,000 on January 4, and NYC’s positivity rate is also trending down. Reduced COVID-19 testing over New Years and other reporting uncertainties are likely playing a role here, but still—NYC cases jumped right back up after Christmas, but haven’t yet jumped up after New Years. I am cautiously optimistic!
    • New research maps out South Africa’s intense Omicron wave. This recent study caught my eye when it was published in Nature this week through accelerated approval. Nearly 100 scientists in South Africa, Botswana, the U.S., Switzerland, the U.K., and other countries collaborated to analyze Omicron’s genetic makeup and the variant’s rapid spread through South Africa, including its ability to cause breakthrough cases and reinfect people who’ve previously had COVID-19. The paper is just one example of the immense collaboration that has taken place over the past month as scientists work to quickly understand this variant. Thank you, scientists!

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  • Omicron updates: ‘mild’ cases can still mean a nasty surge

    Omicron updates: ‘mild’ cases can still mean a nasty surge

    Image
    Data from South Africa and the U.K. suggest that Omicron patients are less likely to require intensive hospital care than those infected with previous variants. Chart posted on Twitter by Paul Mainwood.

    It’s now been over a month since Omicron arrived in the U.S., and the variant’s impact is clear: January is about to be nasty. Here are the major updates from this week:

    • Omicron continues to cause the majority of new cases in the U.S., but the CDC revised its estimates down this week. On Monday, the agency updated its variant proportions estimates; according to the new data, Omicron caused 59% of new cases in the U.S. in the week ending December 25. Notably, this was lower than the previous week’s estimate of 73%. As I explained in a Twitter thread, the CDC’s variant proportions data are estimates with very wide confidence intervals, based on sequencing data that are reported with a lag of multiple weeks. And the agency’s slow pace of updates means that its estimates are unlikely to match the actual variant situation in the U.S. anyway. Still, the CDC data do tell us that Omicron is causing the majority of U.S. cases right now, and that it became dominant over Delta in under one month.
    • Outdoor concerts in Puerto Rico were a superspreading event for Omicron. Puerto Rico has been a pandemic success story, with one of the highest vaccination rates in the nation. But the territory is currently reporting record COVID-19 cases thanks to Omicron, with an increase of over 5,000% in the space of two weeks. One reason for the increase: a series of concerts by the Puerto Rican rapper Bad Bunny, which have now been connected to at least 2,000 cases according to Puerto Rico’s Office of Epidemiology. The concerts took place in an outdoor stadium, and audience members had to be vaccinated and wear a mask to attend. The high number of cases connected to this event indicates Omicron’s high transmissibility, even in outdoor settings.
    • South Africa’s Omicron wave continues to decline, and London may be seeing a similar pattern. Omicron cases have now been decreasing in South Africa for more than two weeks, with a 30% decline from December 18 to 25. The country’s leaders recently lifted a curfew from midnight to 4 AM, though public gatherings are still restricted to 1,000 people indoors and 2,000 outdoors. A similar decline may be starting in London, another major Omicron hotspot—though holiday reporting delays and high testing demand make it hard to say for sure.

    • Continued evidence that Omicron cases are more likely to be mild. Data out of South Africa continue to show that patients infected with Omicron have a lower risk of severe symptoms than those infected in past waves. One study, published this week in JAMA, finds that the country’s fourth wave has impacted younger patients with “fewer comorbidities, fewer hospitalizations and respiratory diagnoses, and a decrease in severity and mortality.” As I’ve written before, this is likely thanks to South Africa’s high prevalence of immunity from past infections. But a growing number of lab studies are also showing that Omicron may have inherent biological qualities that make it more mild, including a reduced capacity to infect lung cells compared to past variants.
    • It is worth noting, however, that mild, in the clinical sense, means that your case does not require hospitalization. A patient could have a high fever, become bed-bound for days, and even face Long COVID symptoms while still fitting the “mild disease” classification, as Nsikan Akpan discusses in this Gothamist article about his own experience with Omicron. Reminder: we still have next-to-no data on how Omicron may impact the likelihood of Long COVID.
    • Studies continue to indicate that vaccines protect against severe disease from Omicron, though protection against infection is less robust. A new preprint posted this week finds that “most of your T cell responses from vaccination or previous infection still recognize Omicron,” explained study author Wendy Burgers in a Twitter thread. T cells are a type of immune system cell that participates in long-term response; their recognition of Omicron means that vaccinated people are still well-protected against severe disease. At the same time, a new study set to be published in Nature found that vaccinated people who’d received two doses had limited protection against infection, while people with three doses or multiple doses and a prior infection were better protected.
    • Antibodies made during an Omicron infection could provide protection against Delta. In Omicron hotspots, people who recently caught Delta have been readily infected by the new variant. But an Omicron infection may lead to anti-Delta antibodies in your immune system, according to a new preprint from South African scientists who tested blood samples from Omicron patients in the lab. “The researchers found, unsurprisingly, that the patients’ blood contained a high level of antibodies potent against Omicron,” explained Carl Zimmer in the New York Times. “But those antibodies proved effective against Delta, too.” If other studies back up this finding, it could mean that regions with Omicron waves will be protected from Delta resurgence.
    • Pediatric hospitalizations are rising as Omicron spreads, but the variant is not necessarily inherently worse for children. In New York City, one of America’s Omicron hotspots, pediatric hospitalizations increased four-fold from the beginning of December through last week, according to the New York State health department. State leaders are encouraging parents to get their kids vaccinated, as less than one-third of children in the five to 11 age group had received at least one dose as of December 24. As the New York Times points out, low vaccination rates for young kids, combined with the sheer number of cases caused by Omicron, are likely to blame for this increase—rather than some inherent quality of Omicron making it more severe for children.
    • The Omicron surge will be bad in the U.S., but it may boost nation-wide immunity for a few months afterwards. I highly recommend reading through this story by STAT’s Megan Molteni, which walks through several potential scenarios for the Omicron winter surge in the U.S. Some highlights: while South Africa’s short wave is promising, it might not translate to the U.S.; the country will be “in a viral blizzard nationwide” for the next few weeks; massive numbers of Americans will be infected (though their cases may be mild and go unreported); the whole world may be in a similar situation; and those huge case numbers could translate to a lot of immunity in the future. “The thing Omicron will do, because it’s going to infect 40% of the entire world in the next two months, is it will raise population-wide immunity for a while,” Chris Murray, director of IHME, told STAT.

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  • Omicron updates: A major surge is underway in the U.S.

    Omicron updates: A major surge is underway in the U.S.

    Within a week, Omicron has jumped from causing an estimated 13% of new COVID-19 cases in the U.S. to 73% of new cases. Chart via the CDC.

    The majority of new COVID-19 cases in the U.S. are now caused by Omicron, and a massive surge is underway. But there’s good news: the variant continues to appear less likely to cause severe disease than past coronavirus strains, and South Africa’s wave may have already peaked.

    Here are the highlights of Omicron news this past week:

    • Omicron is now causing the majority of cases in the U.S. Last week, I wrote that the CDC’s estimates of new COVID-19 cases caused by different variants were providing a delayed, incorrect look at Omicron in the U.S. This past Monday, the ramifications of that delay were made clear: the CDC updated its estimates, showing that 73% of new cases in the week ending December 18 were caused by Omicron. (The agency’s previous estimate: 3% of new cases.) The agency also updated its estimates for prior weeks, to 13% in the week ending December 11 and 1% in the week ending December 4. It’s important to note that, as Trevor Bedford points out in this STAT News interview, these numbers are estimates generated by CDC algorithms. New sequencing data are always reported with a lag, and the true share of cases caused by Omicron is almost certainly even higher by now.
    • The Yankee Candle Index shows a major rise in COVID-19 cases. One of the most common COVID-19 symptoms is loss of smell. As a result, COVID-19 surges in the U.S. tend to correspond with increases in one-star reviews of Yankee Candles, in which reviewers complain that they can’t smell their candles—a phenomenon known as the Yankee Candle Index. And in the past few weeks, those one-star Yankee Candle reviews have shot up again, to higher levels than even last winter. This SFGATE article provides a nice summary of the situation.
    https://twitter.com/zornsllama/status/1473575508784955394
    • In South Africa, Omicron cases continue to go down. COVID-19 case numbers in South Africa dropped by about 20% between December 15 and December 22, prior to any holiday reporting interference. Several South African scientists have said that the country appears to be “over the curve,” with similar case patterns observed in the Omicron hotspot of Gauteng. This news is puzzling for some researchers—and might be tied to insufficient testing and/or high numbers of mild and asymptomatic cases—but it still bodes well for Omicron outbreaks in other countries. London may be seeing the beginning of a case drop right now, as well.
    • It’s tough to say whether Omicron is more mild because of inherent biology or prior immunity. As the scientists studying Omicron in the lab continue to share their findings—and South Africa continues to see low numbers of cases requiring hospitalization—evidence is growing that Omicron seems to be less likely to cause severe disease than past variants. But scientists remain skeptical, as this recent piece in Science magazine explains. Some aspects of Omicron’s biology, like its reduced capacity to infect lung cells, may make it inherently less virulent. At the same time, vaccines and prior infections confer protection against severe disease, particularly in the form of T cells.
    • Omicron might be making people sick—and contagious—faster than past variants. Scientists call the gap between exposure to a virus and the beginning of symptoms the “incubation period.” For the original coronavirus, this period was five or six days, Katherine J. Wu writes in The Atlantic. For Omicron, it may be as short as three days. While it’s challenging to study incubation periods, Wu writes, early data indicate that Omicron makes people sick in less time than prior variants—thus shortening the time that we have to identify and stop infections. Her piece also discusses the implications that this shorter incubation period has for testing.

    • Oral swabs may be more accurate than nasal swabs in identifying Omicron infections. In the past few days, I’ve seen some discussion on Twitter about swabbing one’s throat in addition to one’s nose when rapid testing for a potential Omicron infection. One recent preprint from South Africa suggests that Omicron might cause more viral shedding in saliva and less in the nose than past variants, meaning tests that rely on samples from the throat could be more likely to catch Omicron infections than tests that rely on nasal swabs. If you’d like to try the saliva swab method yourself, this video from Public Health England is helpful.
    • Omicron protection from booster shots may be short-lived. In the latest Omicron briefing from the U.K. Health Security Agency, one finding stuck out: while booster shots provide additional protection against Omicron infection, this protection begins to wane several weeks after vaccination. “Updated vaccine effectiveness analysis shows mRNA boosters beginning to wane from one month (week 5-9) for Omicron, and as low as 30-50% effective from 10 weeks post-booster,” wrote Meaghan Kall in her Twitter thread summarizing the briefing. If you haven’t gotten your booster shot yet, definitely do so—the shots also increase protection from severe disease, and that doesn’t wane. But this finding suggests that Omicron-specific boosters may be needed in the coming months.
    • Antiviral pills for COVID-19 will soon be available, and they work against Omicron. This week, the FDA authorized two antiviral COVID-19 pills for emergency use in the U.S.: one pill made by Merck (about 30% effective against hospitalization and death in clinical trials), and the other made by Pfizer (about 90% effective). Both pills are designed to prevent severe disease in vulnerable adults, such as the immunocompromised, and both work well against Omicron infections—since they target pieces of the coronavirus outside of the heavily-mutated spike protein. While the pills require a positive COVID-19 test for prescription (a challenging task, as testing demand continues to increase), their authorization is still a source of hope as the variant spreads.
    • IHME predicts “enormous spread of Omicron,” but with most cases mild or asymptomatic. The Institute of Health Metrics and Evaluation (IHME) at the University of Washington has predicted that the U.S. could see 140 million new coronavirus infections between January and March 2022, with a peak of 2.8 million infections a day. That could amount to 60% of the U.S. getting infected, the IHME director told USA Today. Note, however, that the institute predicts infections, not reported cases; the modeling suggests that the vast majority of these cases will be mild or asymptomatic. This prediction is in line with estimates of existing COVID-19 immunity in the U.S.: for example, Trevor Bedford said that 80% to 90% of Americans currently have some degree of protection from vaccination or prior infection in the STAT News interview linked above.
    https://twitter.com/JuliaRaifman/status/1472972206246440971

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  • Omicron updates: Spreading rapidly in the U.S.

    Omicron updates: Spreading rapidly in the U.S.

    We keep learning about this dangerous variant as it spreads through the U.S. and the world. A few major updates from this week:

    • Omicron is spreading rapidly in the U.S. Last Tuesday, the CDC announced that Omicron had gone from causing 0.4% of new COVID-19 cases nationwide in the week ending December 4, to 2.9% of cases in the week ending December 11. That’s a seven-fold increase over the course of a week; the variant appears to be doubling every two to three days, based on data from the U.K. We can assume that it will be the dominant variant in the U.S. by the end of December, if not sooner.
    • U.K. data provides information on just how fast Omicron can spread. The U.K.’s comprehensive genomic surveillance system, combined with its unified national public health system, allows British researchers to analyze their country’s Omicron cases in high detail. According to the latest briefing from the U.K. Health Security Agency (summarized by Meaghan Kall): risk of reinfection with Omicron is three to four times higher than with Delta; risk of household transmission with Omicron is two to three times higher than with Delta; and the variant is doubling every two days—or even every 1.5 days, in some parts of the U.K.
    Omicron’s rapid spread in London, compared with prior Delta cases. Chart by Theo Sanderson; see his Twitter for the full animated version.

    • New research from Hong Kong provides insight into why Omicron spreads so fast. Preliminary data from a Hong Kong University research team suggests that, within 24 hours of an Omicron infection, the virus “multiplied about 70 times faster inside respiratory-tract tissue than the Delta variant,” reports Megan Molteni at STAT News. More virus in the respiratory tract means more virus getting out into the air, Molteni explains. At the same time, the variant seems to be worse at multiplying within lung tissue, which may contribute to milder disease. While the Hong Kong study has yet to be peer reviewed, this finding aligns with reports of superspreading events among fully vaccinated people.
    • Skepticism about “Omicron being mild” continues despite more reports. Early this week, the largest health insurance company in South Africa posted results of a study examining the country’s Omicron wave. The study found that risk of hospitalization was 29% lower for Omicron patients than it had been during the country’s spring 2020 COVID-19 surge. While this finding follows other reports out of South Africa, experts are still skeptical: in part because it can take weeks for a coronavirus infection to progress to hospitalization, and in part because South Africa’s population has a lot of prior immunity from past surges and vaccinations. Also, a “milder” variant that’s more transmissible can still lead to significantly more hospitalizations.
    • We’re getting more evidence that vaccination protects against severe disease from Omicron. Basically: two shots are good, three shots are better. “Though these data are preliminary, they suggest that getting a booster will help protect people already vaccinated from breakthrough or possible severe infections with Omicron during the winter months,” writes NIH Director Dr. Francis Collins in a recent blog post summarizing both laboratory and real-world studies. If you’re eligible for a booster and haven’t yet gotten it, now is a great time.
    • But: We don’t know how well vaccines protect against Long COVID from an Omicron infection. As many experts continue to say that Omicron cases are mild for those who are vaccinated, the Long COVID experts and advocates I follow have pointed out that a mild breakthrough case can still lead to this prolonged condition. “Omicron is a huge individual threat,” wrote Long COVID researcher Hannah Davis on Twitter recently. “A 15-30% chance of being disabled for at least a year, but likely for the rest of your life, is a bigger threat than most of us ever faced ever before the pandemic.”
    • New York City is an Omicron hotspot in the U.S. As I noted in today’s National Numbers post, this variant has clearly hit NYC, as seen in record case numbers and felt in long lines for testing throughout the city. According to CDC estimates, Omicron was causing about 13% of new cases reported in New York and New Jersey in the week ending December 11. One week later, knowing how fast Omicron has outcompeted Delta in the U.K. and elsewhere, we can assume that it’s now causing the majority of cases in this region.
    • Other U.S. states and regions may be behind in their Omicron sequencing, so assume it’s spreading in your area even if it hasn’t been officially identified yet. As I’ve written before, genomic surveillance in the U.S. is geographically very spotty. NYC is a clear hotspot, but it’s also a city with a lot of sequencing infrastructure. In other parts of the country, Omicron may not have been formally identified yet—but that doesn’t mean it isn’t spreading. Take Orlando, Florida as an example: wastewater sampling in the surrounding county found that Omicron was completely dominating the community this week, according to AP, even though “practically no cases of clinical infection” have been reported.
    • Good news: South Africa’s case numbers are now trending down. As of yesterday, COVID-19 case numbers in Gauteng, the center of South Africa’s COVID-19 outbreak, as well as in other parts of the country, seem to be turning around. Computational biologist Trevor Bedford offered some potential explanations in an interview with New York Magazine: limited testing capacity and milder disease may lead to underreporting of COVID-19 cases in South Africa; less of the population may be susceptible due to prior immunity; and the variant may spread so fast that it can quickly burn through social networks and other avenues of transmission. We’ll need to see whether South Africa’s decline holds, and whether we see similar patterns in other Omicron hotspots.
    • The U.S. is not prepared for an Omicron surge. If you haven’t yet, take some time today to read Ed Yong’s latest feature in The Atlantic, which discusses how the U.S. has failed to learn from past COVID-19 outbreaks and prepare for the Omicron surge that has already arrived. “Rather than trying to beat the coronavirus one booster at a time, the country needs to do what it has always needed to do—build systems and enact policies that protect the health of entire communities, especially the most vulnerable ones,” Yong writes.
    • Omicron has altered the trajectory of the pandemic. Another piece to take time for today is this article in Science by Kai Kupferschmidt, discussing the “really, really tough winter” that scientists now see coming. Kupferschmidt explains that, even if many Omicron cases are mild, the variant is still spreading fast enough that it could land a lot of people in the hospital. In addition, the variant “may bring other, unpleasant evolutionary surprises” if future coronavirus variants evolve out of Omicron, Kupferschmidt writes.

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