Influenza vaccination may lead to better protection against COVID-19

Mihai Netea and colleagues of the research theme Infectious diseases and global health have shown that a flu vaccination enhances the immune response against the new SARS-CoV-2 coronavirus. This may possibly lead to a better protection against a COVID-19 infection. They show that hospital staff who received a flu vaccine in the winter 2019-2020 were less likely to be infected with the coronavirus.

The study has been published on MedRxiv pending peer review.

Every year, the flu causes 290,000 to 650,000 deaths worldwide and a large group of people who are at increased risk of a flu infection are invited to get the flu vaccine. Healthcare personnel also receive an invitation for the influenza vaccine, which is important for both themselves and their patients.

Influenza vaccine ensures trained immune response

The study looked at two things. Firstly, a lab model showed that last winter's influenza vaccine leads to an improved immune response against the new SARS-CoV-2 coronavirus in cells of healthy individuals: a so-called 'trained immune response'. Previous studies have shown that it can provide broad protection against infections.

Secondly, the number of COVID-19 infections among health care personnel was examined, distinguishing between groups that were vaccinated against influenza and those that were not vaccinated with the influenza vaccine in autumn 2019. The analysis showed that health care personnel who were vaccinated with the flu vaccine were less likely to have a COVID-19 infection: the number of COVID-19 infections was 39% lower in the vaccinated group.

Vaccinated staff less frequently infected with COVID-19

These data, like some recent other reports, argue for a possible beneficial effect of influenza vaccination against influenza and against COVID-19. This means that the flu vaccine could offer partial protection against both infections next winter.

Mihai Netea: "We thought it was important to publish these results now, because the flu vaccine will be made available to a large group of people in the coming period. In addition to protection against influenza, the vaccine could have beneficial effects against the new coronavirus".