Flu shot linked to fewer, less severe COVID cases: study

People who received a flu shot last flu season were significantly less likely to test positive for a COVID-19 infection when the pandemic hit, according to a new study.

The study, published in the American Journal of Infection Control, also indicated that those who did test positive for COVID-19 had fewer complications if they received their flu shot.

"It's particularly relevant for vaccine hesitance, and maybe taking the flu shot this year can ease some angst about the new COVID-19 vaccine," said researcher Hofmann, Associate Professor at the University of Michigan.

For the study, the research team included more than 27,000 patients who were tested for a COVID-19 infection in mid-July of 2020.

Of the nearly 13,000 who got a flu shot in the previous year, 4 per cent tested positive for COVID-19. Of the 14,000 who hadn't gotten a flu shot, nearly 5 per cent tested positive for COVID-19.

The association remained significant after controlling for other variables including ethnicity, race, gender, age, BMI, smoking status and many comorbid conditions.

The researchers found that people who received their flu shot were also significantly less likely to require hospitalisation, although the researchers didn't find a significant difference in mortality between the two groups.

"It is possible that patients who receive their flu vaccine are also people who are practicing more social distancing and following CDC guidelines. 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 researcher said.