Getting flu shot annually has no impact on natural immunity, researchers find

BERGEN, Norway — Recent research revealed there is no negative to getting a flu shot each and every year. New findings debunked earlier studies that had suggested having repeated annual influenza vaccination can prevent natural immunity to the virus, and potentially increase the susceptibility to influenza illness in the event of a pandemic, or when the vaccine does not "match" the virus circulating in the community.



The findings were published in the Journal of Infectious Diseases.



Researchers at the Influenza Center in Bergen, Norway recently concluded that annual influenza vaccination does not increase susceptibility to influenza infection in years of vaccine mismatch. These findings are important because they show that it is only positive to have annual influenza vaccination, and it supports continuing the policy of repeated annual vaccination, commented professor Rebecca Cox, head of the Influenza Centre.



Researchers at the Influenza Centre in Bergen have over a period of five years followed 250 health care workers. They were vaccinated in 2009, and had annual vaccination in all subsequent seasons or no further vaccination between 2010 and 2013.



The results showed that both health care workers who had annual vaccination, and those who did not get annually vaccinated, had the same second line defense, but those who had gotten annual vaccines had a better first line defense. The group that had annual vacccination, had not been prevented from developing natural immunity.



Influenza vaccines have been in use for over 50 years, but there are very few studies that have been able to follow the same people for a long period of time particularly in such a well documented group of vaccinees.