Higher Risk of Vaccine Breakthroughs in People With Substance Use Disorders: US Study

by EditorT

Syringes of the Pfizer-BioNTech at a Covid-19 vaccination centre in the city of Sale, on October 5, 2021. (Fadel Senna/AFP/Getty Images)

By Tammy Hung

People with substance use disorders (SUDs) are more likely to get infected with COVID-19 and end up with adverse outcomes from the infection, according to an Oct. 5 study published on World Psychiatry (pdf).

“Drugs and alcohol affect immune function, which is likely to contribute to the higher risk for infections in individuals with SUD,” reported the study.

Led by the U.S. National Institute on Drug Abuse, the study found that patients with SUDs were more likely to experience vaccine breakthroughs compared to the average vaccinated individual without SUDs.

The risk for contracting COVID-19 in vaccinated individuals was found to be 3.6 percent in individuals that do not suffer from substance use disorders.

Among SUD patients, those with cannabis or cocaine use disorders were approximately twice as likely as non-substance users to undergo breakthrough infections.

Researchers stated that SUD individuals are at higher risk for breakthrough infections because they tend to have concurrent health issues and were associated with “adverse socioeconomic determinants of health,” such as education and literacy-related issues, employment-related issues, and problems related to housing and economic circumstances.

When adverse socioeconomic characteristics were controlled for, people with most substance use disorders—with the exception of cannabis users—no longer had elevated rates of breakthrough infections.

Of SUD patients, those with cannabis use disorder have a higher risk of breakthrough infections even though they tend to be younger with fewer comorbidities.

“This may indicate that additional variables, such as behavioral factors or adverse effects of cannabis on pulmonary and immune function, could contribute to the higher risk for breakthrough infection in this group,” researchers hypothesized.

Researchers also reported that those with substance use disorders were more likely to have diseases affecting the heart, brain, immune system, blood vessels, lungs, metabolic organs, liver, and kidneys.

“The high frequency of comorbidities in SUD patients is also likely to contribute to their high rates of hospitalization and death following breakthrough infection,” the study concluded.

Among the control and the SUD population, individuals who have completed the Pfizer-BioNTech vaccination series were more likely to experience breakthrough infections than those who have completed the Moderna vaccine series, after accounting for socioeconomic and health factors.

Researchers included 549,189 patients in the control group and 30,183 patients in the SUD group, of whom 2,058 suffered from cannabis use disorder, 1,011 from cocaine, 2,379 from opioids, and 21,941 from tobacco.

Both groups had been fully vaccinated with either two doses of Pfizer-BioNTech or Moderna, or a single dose of Johnson & Johnson vaccine and had not contracted SARS-CoV-2 previously.

The study covered months when the Delta variant first appeared in the United States, including July and August 2021.

Tammy Hung

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