Flu shot administration linked to significantly less likelihood of Covid-19 infection: Study

New study suggested that people who have been administered with the flu shot are significantly less likely to contract novel coronavirus.

Those who test positive after flu shot administration may only demonstrate mild symptoms or face lesser complications.

Senior author Marion Hofmann Bowman, associate professor of internal medicine and a cardiologist at Michigan Medicine Frankel Cardiovascular Centre said, “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.”

For the study, the authors analysed medical charts of over 27,000 patients who were tested for Covid-19 infection at Michigan Medicine between March and mid-July of 2020.

Of the nearly 13,000 who got a flu shot in the previous year, four per cent tested positive for Covid-19. Of the 14,000 who hadn’t gotten a flu shot, nearly five per cent tested positive for Covid-19, the study noted.

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

The researchers observed that people who received the flu shot were also significantly less likely to require hospitalisation.

However, the researchers didn’t find a significant difference in mortality between the two groups. Also, no participant tested positive for both infections at the same time.

The underlying mechanism behind the association isn’t yet clear, Hofmann noted.

“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,” she said.

The study was published in the American Journal of Infection Control.