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People with mental illnesses are potentially at higher risk of breakthrough infection with SARS-CoV-2 following complete COVID-19 vaccination. According to the results from a retrospective cohort study, this is especially true for older persons.
After it was shown that even complete vaccination does not guarantee protection against breakthrough infections, researchers began seeking other potential risk factors. Kristen Nishimi, PhD, data science postdoctoral fellow in psychology at the San Francisco Veterans Affairs Health Care System, California, and her team analyzed data collected between February 2020 and November 2021 from 263,697 US veterans (predominantly male, age around 65 years) who were doubly vaccinated against COVID-19 and who had not had any prior documented SARS-CoV-2 infection.
All Mental Disorders Implicated
At least one mental illness had been diagnosed in 135,481 (51.4%) of the veterans. A SARS-CoV-2 breakthrough infection was detected in 39,109 (14.8%) of the subjects during the observation period. People with mental illness exhibited a 7% higher incidence of breakthrough infections — even after taking possible disrupting factors into consideration, including smoking and comorbidities (adjusted relative risk [aRR], 1.07). The relative risk was highest in the adjusted models for adaptation disorders (aRR, 1.13) and substance abuse (aRR, 1.16) — but the risk was increased across all other mental disorders, too.
Age Increased Risk
The association between mental illnesses and breakthrough infections can be seen in people younger than 65 years as well as those older than 65 years. However, the correlation was more robust, and the risk more strongly pronounced, in the older group (aRR, 1.10, vs aRR, 1.03).
Mental illnesses may be associated with an impaired cellular immunity and, therefore, with a weaker immune response. It is also conceivable that people with mental illness are more careless in complying with protective measures against COVID and are at greater risk of infection.
Among other things, the authors highlighted the potentially incomplete datasets and the exclusion of conditions not included in the Veterans Affairs Health Care System as limitations of their study. More frequent testing of mentally ill people would be helpful.
Despite these limitations, it can be hypothesized that people suffering from mental illnesses constitute a risk group for breakthrough infections. Booster vaccinations are an important prevention strategy here, especially for older people.
This article was translated from German and appeared on Coliquio.