The flu vaccine is only 3% effective at protecting against circulating influenza, compared with around 50% vaccine effectiveness seen in recent years, Public Health England officials have admitted.
PHE said this was because the flu season has been ‘dominated’ by circulation of influenza A(H3N2) subtype viruses, which ‘cause particular problems for vulnerable groups such as the elderly and has resulted in care home outbreaks, hospitalisations and excess mortality in those over 65 years’.
The study of 1,314 patients follows earlier reports from PHE that showed a number of different influenza A(H3N2) strains of flu have emerged this year, pointing to reduced effectiveness of the vaccine, but until now it was unclear what proportion of flu cases were due to these.
Despite the low effectiveness, PHE is still urging people to get vaccinated so they have some level of protection.
Dr Richard Pebody, PHE’s head of flu surveillance and author of the study, said: ‘Throughout the last decade, there has generally been a good match between the strains of flu in the vaccine and those that subsequently circulate, so it’s crucial that these results do not discourage people in at-risk groups from having flu vaccination now, or in the future.
‘The current vaccine is still expected to protect against flu A(H1N1)pdm09 and flu B – both of which may yet circulate this season, so anyone in an at-risk group should still get vaccinated if they have not already.’
PHE said recent surveillance data suggest influenza activity is stabilising, but added that excess mortality is still running particularly high even for the time of year, particularly in the elderly, which it said highlighted ‘the importance of early prescribing of antivirals for vulnerable groups to reduce the risk of serious illness’.