While the overall risk is low, people with substance use disorders such as drug and alcohol abuse may be more susceptible to a breakthrough COVID-19 infection than those without the disorders, research published Oct. 5 in World Psychiatry suggests.
Researchers from Case Western Reserve University in Cleveland and the National Institute on Drug Abuse evaluated EHRs of nearly 580,000 fully vaccinated people in the U.S. between Dec. 1, 2020, and Aug. 14, 2021, who had not had COVID-19 before. Of those, about 5 percent had a diagnosed substance use disorder.
About 7 percent of fully vaccinated people with substance use disorders developed a breakthrough COVID-19 infection, compared to 3.6 percent of people without such disorders, the findings showed. The risk differed based on the type of substance abuse disorders, ranging from 6.8 percent for people with tobacco use disorder to 7.8 percent for cannabis use disorder.
Nearly 23 percent of breakthrough COVID-19 patients with these disorders were hospitalized, and 1.7 percent died. The rates were 1.6 percent and 0.5 percent, respectively, among people with the disorders but no breakthrough infection. Overall, the risk of severe outcomes related to breakthrough infections was higher among patients with substance use disorders compared to patients without.
People with substance use disorders were more likely to have other chronic conditions and adverse socioeconomic characteristics, which is likely why the risk of breakthrough infections among this group was higher, researchers said.
The risk was not different for people with substance abuse disorders compared to those without after researchers controlled for these factors. The exception was for people with cannabis use disorders, who still had a 55 percent higher risk of breakthrough infections. Researchers hypothesized this may be due to the drug's effect on lung and immune function.
"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," said NIDA Director Nora Volkow, MD, one of the study's lead authors.