Even before the federal government's recent decision last week to authorize COVID-19 boosters all adults, it had already recommended them in October for people with certain high-risk conditions. Along with with illnesses like diabetes and heart disease, that list included mental health conditions.
The decision to prioritize people with psychiatric diagnoses in the early rollout of boosters came after a growing number of studies linked mental health disorders with higher risk of both COVID-19 infection and of serious outcomes.
Last year, researchers analyzed data from five hospitals in the Yale New Haven Health System to see how people with a mental health diagnosis who were hospitalized with COVID-19 fared compared to others.
"What we found was we had a higher level of mortality for those that had a prior psychiatric history," says psychiatrist Dr. Luming Li, who was working on her Master's degree at Yale University at the time.
The risk of death from COVID-19 went up by 50% for those with a history of mental illness compared to those with no such history, says Li, who is now the Chief Medical Officer at the Harris Center for Mental Health and IDD in Texas.
Another study published last year looked at a nationwide database of electronic health records with information on people who'd tested positive for COVID-19 and those who were hospitalized.
If an individual had a history of a mental disorder, they were more likely to get infected," says study author Dr. Nora Volkow, director of the National Institute on Drug Abuse. "And if they got infected, then they were more likely to have negative outcomes, such as hospitalization and death."
There are several things going on that explain this, she says.
For one, mental illnesses change people's behaviors which can make them less likely to protect themselves from an infection, with measures like social distancing or wearing masks.
Second, people with mental illness tend to have poorer overall health and many chronic health problems, like diabetes, cardiovascular problems, kidney disease.
"It is this very high prevalence of comorbid medical conditions that's likely to actually be putting them at greater risk for negative outcomes [from COVID-19]," says Volkow.
It's well known that people with mental illness on average live shorter lives and die of health conditions other than their psychiatric diagnosis.
"They suffer prematurely from chronic illnesses, medical neglect," says Dr. Ashwin Vasan, who is president and CEO of Fountain House, a mental health nonprofit.
They are also among the most isolated in society, he says, and that isolation takes an immense toll on their bodies putting them at a higher risk of chronic illnesses.
"There have been study after study showing that it leads to inflammation, immunologic stress, neurodegenerative decline, immunologic impairment, endocrinological impairment," says Vasan. It's equivalent to smoking 15 cigarettes a day, he notes.
And many medications used to treat mental illnesses, particularly antipsychotics also increase risk of these chronic health problems, says Volkow.
"This has been one of the main challenges that we have with the use of antipsychotics overall, which help control certain symptoms in schizophrenia but are negatively associated with a much higher risk of diabetes and hypertension and metabolic diseases," she says.
Certainly the risk isn't the same for all psychiatric diagnoses. It's higher for people with serious mental illness, than say mild depression. But as Vasan pointed out, mental illness is not a static thing.
"People's severity of mental illness and impairment can ebb and flow depending on the amount of care and support they're getting," he says. "Whether or not you're in the throes of a crisis or managing your chronic mental illness, we know on balance, at a population health epidemiologic level, that you're at greater risk."
There's also a clear overlap between serious mental illness and homelessness and substance abuse, which are also linked to high risk of infection and severe COVID-19.
"About 40% of our chronically homeless population has serious mental illness and addiction," says Vasan.
Most of the 13 million people with serious mental illness in the US are on Medicaid, he says, but 40% have no access to care at all.
"This is a systematically marginalized, sicker population that has less access to care and supports," he says.
For all these reasons, Vasan and other mental health experts were glad to see that CDC prioritized people with mental illness for COVID-19 vaccination, something they say should have happened long before.
But many people with mental illness, especially those with serious mental illness (people with significant impairments in their daily functioning) may not be aware of their own risks, or the new recommendations, says Li.
It's important for both health care workers and family members to also be aware of the risks of serious COVID-19 faced by people with mental health diagnoses, and help make sure they are vaccinated, says Li.
"It's going to be a very important first step to make sure that they have their vaccines to start out with and then, second, to be able to get the boosters," she says.