October 7, 2021

Study Examines Risk of Breakthrough Infections for People with Substance Use Disorders

Vaccinated people with a substance use disorder are more likely than other vaccinated people to experience breakthrough infections of COVID-19 and their outcomes are more likely to be severe, according to a study led by researchers from the National Institute on Drug Abuse (NIDA), which is part of the National Institutes of Health. The study of approximately 580,000 fully vaccinated people found that 7 percent of those with substance use disorders had a breakthrough infection, compared to 3.6 percent of those without substance use disorders. Additionally, during the study period 22.5 percent of those with substance abuse disorders who acquired a breakthrough infection were hospitalized and 1.7 percent died, compared to 1.6 and 0.5 percent, respectively, for those without substance use disorders.

NIDA Director Nora D. Volkow, MD, an author of the study, affirmed that vaccinated people remain far less likely to be infected than those who are unvaccinated. “First and foremost, vaccination is highly effective for people with substance use disorders, and the overall risk of COVID-19 among vaccinated people with substance use disorders is very low,” Volkow said. "We must continue to encourage and facilitate COVID-19 vaccination among people with substance use disorders, while also acknowledging that even after vaccination, this group is at an increased risk and should continue to take protective measures against COVID-19.”

According to an NIH news release, the increased risk appears to be the result of underlying health conditions such as high blood pressure, heart disease, and obesity, as well as socioeconomic factors such as housing or employment instability, all of which are more likely to be present in individuals with substance use disorders. When controlling for these factors, the excess risk for people with most substance abuse disorders disappears; however, individuals with cannabis use disorder were still 55 percent more likely to have a breakthrough infection than people without substance use disorders, even though cannabis users tend to be younger and have fewer underlying health conditions. The effects of cannabis on lung function may play a role in this increased risk, according to the study’s authors.

The study appears in World Psychiatry.

Related: Read “Confronting Two Crises: The COVID-19 Pandemic, the Opioid Epidemic, and the IH” in the January 2021 issue of The Synergist.