What's really going on with flu this winter?

"Scientists who track the multitude of flu viruses around the world noticed seven fresh mutations appear in a strain of influenza a type called H3N2 in June. This newly mutated virus rapidly became the dominant form of H3N2 and was named subclade-K. The flu season took off a month early in the UK hinting the virus may have the potential to spread more widely than normal and it was too late to adjust this year's flu vaccine to match the new mutations."

""It was basically spreading at a very similar speed to previous years, it was towards the upper end, but it wasn't an outlier," says Prof Christophe Fraser, who is analysing the spread of the virus at the Pandemic Sciences Institute at the University of Oxford. His team's latest analyses, still to be published, suggest the mutations did give the virus a slight edge at slipping past our immunity in the region of 5-10% more than usual."

Flu kills thousands every winter and puts intense strain on hospitals. Scientists observed seven mutations in an H3N2 strain in June, creating a subclade named K that rapidly became dominant. The season began a month early in the UK and the vaccine could not be adjusted to match the new mutations. Analyses indicate the subclade-K spread at a similar speed to previous years, toward the upper end but not an outlier. The mutations likely confer a modest immune-escape advantage of about 5–10%. It is unclear whether the advantage applies across all ages or mainly affects children and young adults.

Read at www.bbc.com