A new study by University of Georgia researchers reveals that natural immunity from previous flu infections can impact the effectiveness of future influenza vaccinations. This finding suggests that the estimated 20% of Americans who contract the flu annually may gain an unexpected advantage in battling future variants of the virus.
The research, conducted on ferrets, demonstrates that preexisting immunity developed through natural infection helps strengthen immune responses to subsequent vaccinations. Ye Shen, lead author of the study published in Vaccine, explained, "We didn't fully understand how preexisting immunity through natural infection with different influenza strains changes vaccine-elicited immune responses before this study."
The study tested vaccines made from various flu strains on ferrets previously infected with the virus. Results showed that the ferrets infected with one strain of flu exhibited a heightened immune response when vaccinated against the same strain. Notably, overall immunity also improved significantly when the animals received a vaccine targeting a different flu strain after recovering from the original infection.
Search Antibodies Search Now Use our Antibody Search Tool to find the right antibody for your research. Filter
by Type, Application, Reactivity, Host, Clonality, Conjugate/Tag, and Isotype.
This dual protection mechanism, combining natural immunity against one strain with vaccine-induced responses to multiple strains, provided better overall shielding against the virus. In contrast, ferrets that were only vaccinated without prior infection were more likely to require booster shots due to their lack of natural immunity.
The findings are particularly relevant given the flu virus's constant evolution and the challenges in developing perfectly matched vaccines each season. "In some years, we don't have very good protection from the vaccine because of that mismatch," Shen noted
Future studies will explore more clinically relevant outcomes, including actual infections in humans, to better understand how this enhanced immunity translates to protection against various influenza strains.