People who are vaccinated against COVID-19 who have a history of certain mental health conditions have been found to be at greater risk of breakthrough infection, a study found.
As vaccines are not 100 per cent effective at preventing infection, a “breakthrough infection” is when a fully vaccinated person becomes infected and is more frequent when the levels of the virus circulating through the community are high.
Patients over the age of 65 who had a history of substance abuse, psychotic disorders, bipolar disorder, adjustment disorder and anxiety, were found to have increased risks of up to 24 per cent for infection.
Researchers believe that as well as being due to some riskier behaviour associated with some of the disorders, the finding may also be in part due to impaired immune response.
The researchers from University of California San Francisco and the San Francisco VA Health Care System found that patients under 65 with the same conditions had up to 11 percent higher risk than those without a psychiatric history.
For both age groups, data was adjusted for age, sex, race, ethnicity and vaccine type, as well as for smoking and underlying conditions like obesity, diabetes, sleep apnea, cardiovascular, lung, kidney and liver diseases, HIV and cancer.
‘Possible immunity wanes more quickly’
Published in JAMA Network Open, the study tracked data from more than 250,000 US Department of Veterans Affairs patients who had completed their vaccination schedules against COVID-19.
Just over a half of the patients had received at least one psychiatric diagnosis within the last five years and 14.8 per cent developed breakthrough COVID-19, confirmed by a positive test.
“Our research suggests that increased breakthrough infections in people with psychiatric disorders cannot be entirely explained by socio-demographic factors or pre-existing conditions,” said senior author Aoife O’Donovan, PhD, of the UCSF Weill Institute for Neurosciences and the San Francisco VA Health Care System.
“It’s possible that immunity following vaccination wanes more quickly or more strongly for people with psychiatric disorders and/or they could have less protection to newer variants”.
The risk was 24 per cent higher for over-65s with substance abuse, 23 per cent higher for those with psychotic disorders, 16 per cent higher for bipolar disorder, 14 per cent for adjustment disorder and 12 per cent for anxiety.
The average age of the 263,697 participants was 66 and 90.8 per cent were male.
Smaller effect for under-65s
Surprisingly the study showed significantly smaller effects in the under-65s group.
Researchers suggest this may be due to higher frequency of in-person care for the older group, meaning a higher risk of infection being passed on.
First author Kristen Nishimi, PhD, also of the UCSF Weill Institute for Neurosciences and the San Francisco VA Health Care System, said she believed the rates could be down to “decreased immunological response to vaccine that has been associated with some psychiatric disorders, which may be more substantial in older adults.”
It’s also possible that older adults with psychiatric disorders “may require more frequent in-person care, which could increase their interactions with the health care system,” she noted.
The same researchers conducted another study earlier this year which found people with elevated anxiety and probable post-traumatic stress disorder were more likely to engage in behaviours that put them at risk of COVID-19 infection.