Getting vaccinated against COVID-19 lowers your chances of catching the coronavirus, but people with substance use disorders (SUDs) face higher risks for infection after vaccination compared to those without the disorder.
And marijuana, of all abused drugs included in new research, made the biggest impact in the likelihood someone got a breakthrough infection, defined as those that occur two or more weeks following complete vaccination, according to a new study published Tuesday in the journal World Psychiatry.
Fully vaccinated individuals with substance use disorders were more likely to have breakthrough COVID-19 infections than those without such disorders, researchers found.
An analysis of nearly 580,000 electronic medical records of fully vaccinated people without a prior coronavirus infection revealed that 7% of those with SUDs — involving alcohol, cannabis, cocaine, opioid, or tobacco — had a breakthrough case compared to 3.6% of those without SUDs.
People with SUDs were also more likely to be hospitalized and die from breakthrough infections.
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Among those included in the study, about 22.5% with SUDs required hospitalization, while 1.7% of them died due to their breakthrough case. That’s compared to 1.6% and 0.5%, respectively, among people with SUDs but who didn’t get sick, meaning they were hospitalized or died from other causes.
Researchers learned underlying health conditions, including high blood pressure, heart disease, and obesity, as well as poor socioeconomic factors such as housing and employment instability, were “largely responsible” for the increased risk of breakthrough infections among those with SUDs.
But when researchers accounted for these factors in the data, they found only marijuana use disorder made one more likely (55%) to get COVID-19 after vaccination; all other SUDs had no longer increased risk for breakthrough infection.
The team with the National Institute on Drug Abuse and Case Western Reserve University in Ohio suspects the harmful effects of marijuana on lung and immune system function may explain their findings, given the drug is more often used by younger people with few underlying health conditions.
Electronic medical records used in the study did not specify whether people smoked, ate, or vaped cannabis, or used a combination of those methods.
The findings offer an important look into the risks people with SUDs face, a group that was not specifically studied during initial clinical trials. People with SUDs often have weakened immune systems because of drug use and other accompanying health conditions.
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“From previous studies, we knew that people with substance use disorders may be particularly vulnerable to COVID-19 and severe related outcomes.
These results emphasize that, while the vaccine is essential and effective, some of these same risk factors still apply to breakthrough infections,” Rong Xu, professor in the Center for Artificial Intelligence in Drug Discovery at Case Western Reserve University, said in a news release.
“It is important to continuously evaluate the effectiveness of COVID-19 vaccines and the long-term effects of COVID-19, especially among people with substance use disorders.”
Generally, the risk of getting COVID-19 after vaccination for those with SUDs varies depending on what kind of drug is abused. The study found it ranges between 6.8% for people with tobacco use disorder and 7.8% for those with cannabis use disorder.
“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,” NIDA Director Dr. Nora Volkow, one of the lead authors on the study, said in the release.
“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.”