For the study, researchers looked at electronic health record data on infection rates among 579,372 fully vaccinated individuals in the United States, including 30,183 people diagnosed with substance use disorders. All of the participants were vaccinated between December 1, 2020, and August 14, 2021, and none of them had COVID-19 infections prior to vaccination. While 3.6 percent of people without substance use disorders subsequently got diagnosed with COVID-19, average breakthrough infection rates reached 7 percent among those with addiction issues. “Even after vaccination, this group is at an increased risk and should continue to take protective measures against COVID-19,” says study coauthor Nora Volkow, MD, director of the National Institute on Drug Abuse at the National Institutes of Health in Bethesda, Maryland. Substance use disorders were also associated with worse outcomes in people who did get breakthrough infections. Among those with addiction, 22.5 percent of vaccinated COVID-19 patients had severe infections that required hospitalization, compared with 1.6 percent of vaccinated individuals without substance use disorders. Mortality rates from breakthrough infections were 1.7 percent among people with substance use problems, compared with 0.5 percent among the other vaccinated people in the study. Researchers did find that people with substance use disorders were more likely than other individuals to live in poverty and have other chronic health problems. Once the analysis accounted for these factors, marijuana was still associated with a 55 percent higher risk of breakthrough infections, but other types of substance use no longer appeared to carry an elevated risk. One limitation of the study, however, is that researchers were unable to examine how more contagious versions of the virus, such as the delta variant, might have influenced outcomes. Another drawback is that the analysis was based on health insurance claims that may miss outcomes for people who are uninsured, undocumented, or healthy individuals who might have had asymptomatic COVID-19 infections. RELATED: Questions About the Coronavirus, Answered “From previous studies, we knew that people with substance use disorders may be particularly vulnerable to COVID-19 and severe related outcomes,” says senior study author Rong Xu, PhD, a professor in the Center for Artificial Intelligence in Drug Discovery at Case Western Reserve University in Cleveland. Individuals with substance use disorder weren’t included in clinical trials for COVID-19 vaccines, the authors of the latest study note in their paper. Substance use has been previously linked to an increased risk of developing COVID-19 infections.
Substance Use Depresses the Body’s Immune System
One previous study, published in September 2020 in Molecular Psychiatry, looked at electronic health records data for more than 73 million patients, including more than 12,000 people diagnosed with COVID-19 infections and 7.5 million individuals with substance use disorders. In this study, individuals who had been diagnosed with substance use disorder within the past year were more than 8 times more likely to get a COVID-19 infection. The increased risk was most pronounced with opioids and tobacco, compared with other substances. The exact reason that substance use disorders might make COVID-19 infections more likely or more severe isn’t clear, and the current study doesn’t help to answer this question. However, it’s possible that substance use contributes to a compromised immune system and chronic inflammation, which then makes people less equipped to fight off COVID-19 infections, says Alexander Hatoum, PhD, a psychiatry researcher at the Washington University School of Medicine in St. Louis, who wasn’t involved in the new study. “I think inflammation is the mechanism of action if we are looking across substances, though this link is difficult to test in humans,” Dr. Hatoum says. “People with severe COVID-19 reactions tend to have a larger inflammatory response.” Cannabis may appear to be more strongly linked to COVID-19 infections because many individuals who use this also misuse other substances, Hatoum says. “A diagnosis of cannabis use disorder usually means cannabis is the drug they report issues with, but it’s likely that they use other substances as well,” Hatoum says. “Many cannabis use disorder patients smoke tobacco, almost all drink alcohol, and a few transition to harder substances.” Increased stressors during the pandemic may lead some people to develop substance use disorders and make it harder for others to complete treatment to combat addiction, according to the U.S. Centers for Disease Control and Prevention (CDC). The CDC recommends the following measures for safer substance use when people are struggling with addiction:
Get the COVID-19 vaccine.Wear a mask. But remove masks if a person is unconscious, incapacitated, or otherwise unable to remove it on their own.Stay at least six feet apart from others.Avoid crowds and poorly ventilated indoor spaces.Wash your hands often with soap and water for at least 20 seconds.Avoid touching your face or your injection site with your bare hands. To prevent infection, always wash your hands and wash any injection sites with soap and water before and after handling drugs. If soap and water are not available, you can use alcohol wipes or a hand sanitizer with at least 60 percent alcohol.
The Substance Abuse and Mental Health Services Administration also offers an online treatment locator and a toll-free hotline — 800-662-HELP (4357) — to help people with substance use disorder.
