Dr. Karen Zoufal | 03/29/2021
Significantly fewer coronavirus infections were detected in people who had been vaccinated against the flu than in those who had not been vaccinated. Scientists cannot yet fully explain why this is so. They have published their theories on this in the American Journal of Infection Control.
Of the 27,201 tested patients, 1,218 were Covid-19-positive, which corresponds to 4.5 percent of all study participants. Among those without the flu vaccination, it was 4.9 percent, compared with only 4 percent of those who had been vaccinated. This difference seems small, but in fact the likelihood of a positive Covid-19 test was around 24 percent lower in people with a flu vaccination. In addition, patients who had been vaccinated against the flu required hospitalization and ventilation less often if they contracted Covid-19.
This was not the first study to describe such a protective effect against Covid-19 through the flu vaccination: A number of studies worldwide have found evidence of this connection. Why this is so remains unclear. The researchers say these results are unlikely to be caused by a specific effect of the flu vaccine itself. They believe it is possible that people who choose to be vaccinated will be more cautious and more likely to adhere to measures recommended to combat the spread of Covid-19. But it could also be that the immune system reacts more “more attentively” to other pathogens as a result of the flu vaccination.
The authors point out the benefits of flu vaccination: “The greatest benefit of the influenza vaccine is in preventing the flu. But the potential additional benefits of Covid-19 protection can give indecisive patients the impetus to get vaccinated. Even if the direct link between the influenza vaccine in preventing Covid-19 is small, vaccination can create resources for patients with Covid-19 by reducing the number of patients with influenza hospitalized. “
What: DOI 10.1016 / j.ajic.2021.02.012