âIt is important to continuously assess the effectiveness of COVID-19 vaccines and the long-term effects of COVID-19, especially in people with substance use disorders. “
Rong Xu, Ph.D.
The study, published last week in Global Psychiatry, also found that people with SUD had higher rates of severe COVID-19 outcomes, including hospitalization and death, following breakthrough infections.
“First and foremost, vaccination is very effective for people with substance use disorders, and the overall risk of COVID-19 in vaccinated people with substance use disorders is very low, âsaid NIDA director Nora D. Volkow, MD, lead author of the study. “We must continue to encourage and facilitate vaccination against COVID-19 in people with substance use disorders, while recognizing that even after vaccination, this group is at increased risk and should continue to take protective measures against COVID-19. “
Clinical trials evaluating the effectiveness of COVID-19 vaccines did not specifically include people with SUD, the researchers noted. Many people with SUD are already immunocompromised.
âFrom previous studies, we knew that people with substance use disorders could be particularly vulnerable to COVID-19 and its related serious consequences. These results highlight that while the vaccine is essential and effective, some of these same risk factors still apply to breakthrough infections, âsaid Rong Xu, Ph.D., professor at the Center for Artificial Intelligence in Drug Discovery at Case Western Reserve University. . âIt is important to continuously assess the effectiveness of COVID-19 vaccines and the long-term effects of COVID-19, especially in people with substance use disorders. “
The researchers determined the proportion of people who contracted COVID-19 at least two weeks after their final vaccination. The analysis then matched patients with and without SUD for demographics, socioeconomic factors such as housing or job instability, and lifelong physical illnesses, such as obesity or diabetes.
The researchers also examined whether fully vaccinated people with breakthrough infections had a different risk of hospitalization and death compared to corresponding people without breakthrough infections.
The risk of breakthrough infections was significantly higher in people with MUS than in those without: 7% of those vaccinated with MUS had a breakthrough infection during the study, compared with those who did not: 3.6% of people vaccinated without MUS. The highest risk was 7.8% for people with cannabis use disorders.
However, the increased risk was not due to SUD itself but to concomitant diseases and unfavorable socio-economic characteristics. Once these factors were controlled, people with most MUS were no longer at high risk for breakthrough infections. The exception was cannabis use disorder: these people were still 55% more likely to have breakthrough infections than people without MUS. This was true even though people with cannabis use disorders are generally younger and have fewer concurrent health problems than those with other SUD. The researchers speculated that the detrimental effects of cannabis on lung and immune function may have contributed to the higher risk.