People with substance abuse disorders, depression and other mental health conditions may be at higher risk for COVID-19 -- even when they are fully vaccinated, new research suggests.
"Individuals with psychiatric disorders, and especially older adults with psychiatric disorders, may be particularly vulnerable to breakthrough infections," said study author Kristen Nishimi, a postdoctoral fellow at the San Francisco Veterans Affairs Medical Center and the University of California, San Francisco. "Mental health should be recognized as another important factor to consider when thinking about COVID-19 infection risk."
While the new study only found an association and wasn't designed to say why breakthrough infections may be more likely in people with psychiatric illnesses, researchers have some theories.
"Individuals with psychiatric disorders may have more impaired cellular immunity and blunted responses to vaccines, relative to individuals without psychiatric disorders, possibly resulting in less effective responses to SARS-CoV-2 vaccines," Nishimi said.
What's more, these folks may also be more apt to engage in risky behaviors or be in situations that require more interpersonal interaction, increasing their COVID risk, she said.
For the study, the researchers looked at records of more than 263,000 patients of the U.S. Department of Veterans Affairs (average age: 66). Most participants were male, all were fully vaccinated, and all had at least one test for COVID.
Slightly more than half had been diagnosed with a psychiatric disorder, and 14.8% developed breakthrough infection that was confirmed by a positive COVID test, the study showed.
Overall, folks with mental illnesses had a 3% higher risk than others for breakthrough COVID in 2021.
People with substance use or adjustment disorders -- an overly emotional reaction to a stressful event or life change -- had a notably high risk, the study found.
Overall, the increased risk was highest among those age 65 and older with psychiatric illnesses -- findings that held when researchers controlled for other factors that affect COVID risk, including obesity, diabetes, heart disease and cancer.
The findings were published April 14 in JAMA Network Open.
Nishimi said providers who treat mental health problems should be aware of this increased risk for breakthrough infections among patients with psychiatric disorders.
"More preventative measures like booster vaccinations or increased SARS-CoV-2 screening could be considered for these individuals," she said.
Outside experts agree that people with mental illness and those who care for them should double down on efforts to prevent COVID-19.
"Just like diabetes, heart disease and other underlying conditions, mental health disorders also place people in a higher risk category for COVID-19," said Dr. Len Horovitz, a pulmonologist at Lenox Hill Hospital in New York City.
The new findings make sense, said Dr. John Krystal, chief of psychiatry at Yale-New Haven Hospital.
"Obesity is a risk for COVID-19 because it produces inflammation in the body and affects immune function, and depression does the same thing," Krystal said. "In major depression, you get inflammation in the brain and the body."
In addition, people with mental health issues may be less able to take the necessary steps to prevent infection.
Previous studies -- including one done by Yale researchers at the start of the pandemic -- showed people with a history of psychiatric disorders were more likely to die from COVID than their counterparts without such a history.
"The pandemic isn't over yet, and all of us, especially people with mental illnesses, need to continue to take steps to prevent COVID-19 infection," Krystal said.
The U.S. Centers for Disease Control and Prevention offers tips on preventing COVID-19 infection.
SOURCES: Kristen Nishimi, PhD, postdoctoral fellow, psychology, San Francisco Veterans Affairs Medical Center and University of California, San Francisco; John Krystal, MD, professor, translational research, psychiatry, neuroscience and psychology, Yale School of Medicine, co-director, Yale Center for Clinical Investigation, and chief, psychiatry, Yale-New Haven Hospital, New Haven, Conn.; Len Horovitz, MD, pulmonologist, Lenox Hill Hospital, New York City; JAMA Network Open, April 14, 2022