The HPA said there had been 3,877 laboratory confirmed cases from week 27 to week 51 2012, which was 72% higher than the 2,255 figure reported at the same point in 2011.
“During the two weeks up to 30 December there were 29 hospital outbreaks reported, compared to 70 in the previous fortnight, bringing the total of outbreaks for the season to 590,” the watchdog said yesterday.
It estimated that for each confirmed case, there are a 288 unreported cases as people do not seek healthcare in response to the illness.
The agency said the increase is a trend seen across Europe, Japan and Australia but it is as yet unclear why this is the case.