A universal flu vaccine has proved challenging - could it finally be possible?

"On the basis of surveillance data on which strains were circulating, the WHO selected four that would become the foundation of that year's vaccine. One was an H3N2 virus strain that was the most prevalent of that particular subtype, at that moment. But by the time the vaccine was making its way into people's arms that autumn, a different version of the virus had taken over - and the vaccine was only 6% effective at protecting against it."

"This problem of antigenic drift - when gene mutations cause components of the influenza virus to change, and it evolves away from the vaccines designed to keep it in check - could be reduced by the development of a universal flu vaccine. A shot that provides broad coverage against a wide array of strains could improve efficacy significantly from the 40-60% reduction in risk that flu vaccines typically achieve."

In February 2014, WHO selected four influenza strains for the Northern Hemisphere vaccine, including a prevalent H3N2 strain. By autumn a different H3N2 variant dominated, leaving the vaccine only 6% effective and contributing to a season that was more severe and longer than recent years. Antigenic drift, caused by gene mutations that alter viral components, enables viruses to evolve away from vaccine-induced immunity. A universal flu vaccine that provides broad protection across strains could reduce drift-related failures, improve efficacy beyond the typical 40–60% risk reduction, and remove the need for twice-yearly strain selection and annual vaccination.

Read at Nature