London: Taking various seasonal flu vaccines may become a thing of the past if researchers are able design a vaccine that gives decades-long protection from any flu virus strain.
Anthony S. Fauci, and Gary J. Nabel of the National Institute of Allergy and Infectious Diseases contrast the envisioned universal influenza vaccine with today``s seasonal influenza vaccines.
Current seasonal flu vaccines prompt immune responses that mimic those made following natural exposure to the flu virus. Both exposure and vaccination elicit antibodies directed at the roundish head portion of a lollypop-shaped flu protein called hemagglutinin (HA).
But the composition of HA``s head changes from year to year, gradually becoming unrecognisable to previously made antibodies.
Thus, vaccination must be repeated annually to maintain immunity to the virus.
A universal flu vaccine would have to elicit a type of immune response that rarely occurs naturally, noted Fauci and Nabel. A detailed understanding of flu virus structure may make such a vaccine possible, they added.
For example, scientists have identified a region of HA``s stem that is shared among diverse strains, and a research group at NIAID``s Vaccine Research Center recently created influenza vaccines that elicit antibodies aimed at this shared region, rather than at the quick-changing head.
Animals that received the experimental vaccines were protected from a diverse array of flu virus strains.
They also outlined how such a vaccine might proceed through stages of clinical testing and on toward licensing. For example, they sort the 16 known influenza virus subtypes into three tiers based on their likelihood of causing widespread disease in humans.
The findings were reported in the journal Nature Medicine.