National numbers, September 11

In the past week (September 3 through 9), the U.S. reported about 500,000 new COVID-19 cases, according to the CDC. This amounts to:

• An average of 70,000 new cases each day
• 150 total new cases for every 100,000 Americans
• 19% fewer new cases than last week (August 27-September 2)

In the past week, the U.S. also reported about 32,000 new COVID-19 patients admitted to hospitals. This amounts to:

• An average of 4,600 new admissions each day
• 9.9 total admissions for every 100,000 Americans
• 11% fewer new admissions than last week

Additionally, the U.S. reported:

• 2,200 new COVID-19 deaths (0.7 for every 100,000 people)
• 88% of new cases are caused by Omicron BA.5; 9% by BA.4.6 (as of September 10)
• An average of 25,000 vaccinations per day (per Bloomberg)

It might appear that the U.S. reported a significant drop in COVID-19 cases last week, as the CDC’s numbers dropped to about 70,000 new cases a day last week from 87,000 new cases a day in the prior week. But in fact, the decline was likely exaggerated by Labor Day weekend, as testing labs and the public health workers who crunch data took time off.

Wastewater data from the last two weeks tell a different story. In Biobot’s most recent update, the company reported a slight increase in coronavirus concentration in wastewater at the national level. Regionally, the virus grew in the Northeast, Midwest, and South.

There has been a slight increase in our #COVID19 #wastewater data from last week—a departure from the previous 5 weeks of decline. The national average went up 3% & 3/4 regions experienced small rises (1-6%). Levels in the Midwest fell 1%. Explore more at https://t.co/GBL4twvGGT pic.twitter.com/6SCwvbOMpf

— Biobot Analytics (@BiobotAnalytics) September 7, 2022

While hospital admissions and other healthcare system metrics continue to show a decline, wastewater data is often an advanced indicator for new coronavirus surges. In this case, it could mean the often-predicted fall wave is beginning in some parts of the country. Remember: wastewater surveillance can catch transmission upticks early because it doesn’t rely on individuals getting PCR tests or seeking out healthcare—factors that can cause lags and undercounting in case and hospitalization data.

Potential factors contributing to increased COVID-19 outbreaks might include holiday gatherings and travel, the start of the school year, and new Omicron subvariants taking over. BA.4.6, the lineage from BA.4 that may be even more transmissible, went from causing about 8% of new cases in the week ending September 3 to 9% in the week ending September 10, according to CDC estimates; meanwhile, BA.5’s prevalence dropped by about 1%.

This might seem like a small shift, but it is an indicator of BA.4.6’s capacity to eventually outcompete BA.5—and reinfect people who previously caught a different version of Omicron. BA.4.6 is causing a higher share of cases in the Midwest, specifically in Iowa, Kansas, Missouri, and Nebraska, so those are states to particularly watch for increased COVID-19 spread.

At the same time, the CDC reports that 1% of cases nationwide were caused by BA.2 lineages (not BA.2.12.1) last week. This is likely the work of BA.2.75, another subvariant of concern that the CDC isn’t yet tracking separately. (More on that later in the issue.)

The federal government’s main action to mitigate this probably-coming surge is a new booster campaign, with the Omicron BA.4/BA.5 shots authorized last week. But vaccination numbers have been low so far, with far fewer than 100,000 doses administered each day last week.