Vaccinated persons with substance use disorders have a low overall risk of SARS-CoV-2 breakthrough infection, but higher than the risk among vaccinated people without substance use disorders, according to a new NIH study reported in the journal World Psychiatry.

The retrospective case-control study analysed electronic health records (EHRs) data of nearly 580,000 fully vaccinated people in the United States between December 2020 and August 2021. None of the study participants had had Covid-19 prior to taking the vaccine. Of these, slightly over 30,000 had been diagnosed with substance use disorder.

Seven percent of vaccinated persons with substance use disorders suffered a breakthrough infection during the study, as compared to 3.6% of vaccinated people without substance use disorders. The risk of breakthrough infection was also analysed for different substance use disorders and was found to range from 6.8% for tobacco use disorder to 7.8% for cannabis use disorder. The breakthrough infection was more severe in these patients and also increased the risk of hospitalization (22.5%) and even death (1.7%) compared to 1.6% and 0.5%, respectively among persons with substance use disorder but who did not have a breakthrough infection.

The risk for breakthrough infections was observed to be higher with Pfizer vaccine than the Moderna vaccine (HR=1.49).

According to this study, even fully vaccinated  persons with substance use disorder are at high risk of developing a breakthrough infection. This high risk has been attributed to the presence of multiple comorbid disease conditions and poor socioeconomic status, which further increase the severity of the infection leading to hospitalization and/or death. The compromised immune status, due to substance use, also makes them vulnerable to infection with SARS-CoV-2. This study has shown that the overall risk of COVID-19 infection among vaccinated patients was low, on the other hand, it has also shown that they continue to be vulnerable to infection even after vaccination. Regardless, people with substance use disorders must be encouraged to take full vaccination and also advised to adhere to all preventive precautionary steps against Covid-19.

Reference

1. Wang L, et al. Increased risk for COVID-19 breakthrough infection in fully vaccinated patients with substance use disorders in the United States between December 2020 and August 2021. World Psychiatry. 2021 Oct 5. doi: 10.1002/wps.20921.