This year's flu shot didn't work-because the virus was smarter than the scientists making the vaccine. The virus mutated in ways that the scientists didn't anticipate, and made the seasonal flu jab useless, say scientists at the Wistar Institute. They estimate that just one in four people vaccinated had any protection this year.
Vaccines are prepared on the basis of the previous year's virus, and they work by triggering antibodies that match the virus. But this year's virus mutated in ways that prevented the vaccine's antibodies from binding with it.
The World Health Organization (WHO) has recommended that the next flu vaccine takes account of these recent mutations found in the H3N2 virus, responsible for seasonal flu. Up to 5 million people catch the winter flu, which is responsible for around 500,000 deaths each year.
(Source: Cell Reports, 2015, doi: 10.1016/j.celrep.2015.06.005)