theconversation.com
Early flu season: why you should get your jab sooner this year
Data from the UK Health Security Agency (UKHSA) shows more flu activity in September than in the same month of the past four years. However, flu is still circulating at relatively low levels in the community. If cases continue to rise over the coming weeks, this would suggest the flu season is starting earlier than usual. Flu infections usually begin to climb in October and peak in the coldest months, around January. One of the main types circulating is H1N1, known as swine flu, which caused an epidemic in the UK in 2009-10 and killed 457 people. The H1N1 virus circulating now has undergone changes that make it different from the version targeted by this year’s vaccine. This raises questions about how well the vaccine will protect people against it. Flu viruses change a little from year to year. These changes, known as antigenic drift, can make it harder for the immune system to recognise a virus from a previous infection or vaccination. They affect proteins on the virus’s surface that the immune system recognises, potentially making a vaccine less effective against a changed version. Each year, scientists at the World Health Organization study which flu viruses are circulating and...