Could flu be a bigger problem than Covid this winter? Professor Anthony Harnden, the deputy chair of the Joint Committee on Vaccination and Immunisation, has warned that it might be, suggesting that the low prevalence of flu over recent months could come back to ‘bite us’ as the weather worsens. There are also fears that reduced levels of flu in recent months could make it much harder to develop a successful jab.
In a normal year, the route to a flu vaccine is well trodden. The annual flu vaccination programme first began in England in the 1960s, and since 2000, all over 65s have been offered the jab every year. Healthy children have also been offered a live attenuated influenza vaccine (LAIV) in school, administered as a nasal spray, for the last eight years.
But because developing the flu vaccine effectively involves a sophisticated guessing game, this will be a much more difficult process this year. Flu is an intelligent virus which mutates very quickly and has many different strains; the vaccine must be tweaked annually to try and ‘catch’ the latest variants of concern. Every year, scientists receive flu data from the other side of the world. They use this to predict which strains are the deadliest and most likely to infect their populations. Around now, scientists in the Northern Hemisphere will tweak their jabs based on data from the flu season in the Southern Hemisphere. There’s a problem this year though: there isn’t much flu.
Each year, public health labs perform genome sequencing and analysis on 7,000 influenza viruses on clinical samples collected through flu surveillance from around the world. The WHO publishes a report every February on their recommendations for the influenza vaccines for the Northern Hemisphere based on the previous year’s data. This year’s report is rather stark.