Researchers at Michigan Medicine say they found an association between the flu shot and fewer, less severe coronavirus cases. The study, which reviewed medical charts for more than 27,000 patients, also found that nobody included in the data tested positive for both viruses at the same time.
“It is possible that patients who receive their flu vaccine are also people who are practicing more social distancing and following CDC guidelines,” Marion Hofmann Bowman, M.D., senior author and associate professor of internal medicine and a cardiologist at the Michigan Medicine Frankel Cardiovascular Center, said in a news release. “However, it is also plausible that there could be a direct biological effect of the flu vaccine on the immune system relevant for the fight against SARS-CoV-2 virus.”
The researchers found that between March and mid-July 2020, of the nearly 13,000 who got a flu shot the previous year, 4% tested positive for COVID-19, while nearly 5% of the 14,000 who forwent the flu shot tested positive COVID-19. Those who received the shot were also “significantly” less likely to require hospitalization, according to the news release posted to Eurekalert.org.
Hofmann noted that the underlying cause of the apparent association is not yet clear.
“Instead of a concerning connection between COVID-19 and the flu shot, our publication provides more confidence that getting your flu shot is associated with staying out of the hospital for COVID-19,” Hofmann said.