Adults with substance use disorders have an increased risk of breakthrough cases, according to a new study published this week in the journal World Psychiatry. Though the chances of a COVID-19 case after vaccination were very low in this group, these patients’ odds of a breakthrough case were about twice as high as the odds for adults without substance use disorders, researchers from the National Institutes of Health (NIH) found.
This study is the first I’ve seen to delineate breakthrough case risk in a specific, vulnerable population—besides studies demonstrating higher risk for older adults. As I wrote two weeks ago, a lack of specific data on breakthrough cases has contributed to confusion and debate surrounding who should be eligible for a booster shot in the U.S.
So, how did these NIH researchers determine the risk for people with substance abuse? They used anonymous, electronic health records from 63 healthcare organizations across the U.S., compiled in the TriNetX Analytics platform. The study included health records from about 30,000 patients with substance use disorders, compared with 550,000 patients without these disorders. From this large pool of anonymous data, the researchers were able to determine breakthrough case risk among different patient demographics, different substance use disorders, and more.
I got a chance to talk to Dr. Nora Volkow, director of the NIH’s National Institute on Drug Abuse and one of the study’s lead authors, about this methodology, as I covered the paper for DailyMail.com. I asked her if she expected to see similar studies examining breakthrough case risk for other health risks and occupations.
“Absolutely,” Dr. Volkow said. She told me she’s already seen other papers comparing the risk of a breakthrough with Delta compared to other variants, and that more research looking at specific patient groups may be ongoing. Still, using electronic health records has its drawbacks.
“We are basically basing [the analysis] on the electronic health records,” she said. “But it could be useful to complement this with studies that actually are genotyping, getting information about, what was the virus that is responsible?” In other words: health records from hospitals and clinics typically are not matched with genetic sequencing information, making it difficult to link specific variants with breakthrough case risk.
As for why patients struggling with substance abuse have a higher risk of breakthrough COVID-19: Dr. Volkow said this is largely due to socioeconomic factors, such as lack of access to healthcare, low income, and homelessness. Drugs and alcohol are also capable of weakening patients’ immune systems, though; marijuana in particular can hinder immune system regulation.