Study Links Flu Vaccine to Lower Risk of Contracting COVID-19

Although the 2020-2021 flu season has been exceptionally mild, it’s still a good idea to encourage any employees who have not received their flu shot to do so.

A new study published in the American Journal of Infection Control found that people who received a flu shot this season were less likely to test positive for COVID-19. If they were infected with the SARS-CoV-2 virus, people who had flu shots were less likely to be hospitalized, be placed on a mechanic ventilator, or require a long hospital stay.

Researchers studied data from 27,201 patients who were tested for COVID-19 from February 27, 2020 to July 15, 2020, in the Michigan Medicine healthcare system. Of those patients, the researchers found that 12,997 (47.8%) were vaccinated against the flu between August 1, 2019, to July 15, 2020.

Among the influenza-vaccinated patients, 525 (4.0%) tested positive for coronavirus, compared to 693 (4.9%) of the patients who were not vaccinated for influenza. 

Researchers speculated that the influenza-vaccinated group may have included healthier people with fewer chronic health conditions, accounting for their lower likelihood of contracting COVID-19 or experiencing less severe symptoms. However, they found the patients receiving the flu vaccine tended to have more comorbidities than the unvaccinated group, including higher rates of chronic pulmonary disease (16.4% vs. 13.4%), congestive heart failure (9.2% vs. 6.7%), diabetes (11.1% vs. 9.7%), and hypertension (23.9% vs. 22.3%). Patients receiving an influenza vaccine also tended to be older (48.4 years vs. 46.1 years), female (61.0% vs. 50.9%), and Caucasian (80.1% vs. 74.6).