Flu vaccines: an annual challengeBMJ 2018; 361 doi: https://doi.org/10.1136/bmj.k2705 (Published 27 June 2018) Cite this as: BMJ 2018;361:k2705
- Richard G Pebody, consultant epidemiologist,
- Maria Zambon, consultant virologist,
- Mary Ramsay, head of Immunisation and Countermeasures Division
- National Infection Service Public Health England, London NW9 5EQ, UK
- Correspondence to: R G Pebody
Influenza is a well recognised cause of morbidity and mortality,1 though its impact varies considerably between seasons. It has the highest burden of any infectious disease in Europe, according to the European Centre of Disease Control.23 Influenza viruses change rapidly, and we cannot forecast which will circulate each winter. Because vaccine composition does not always match circulating strains—as seen in 2014-15, which was dominated by H3N2—influenza seasons are a challenge to healthcare systems already under pressure. Controlling and preventing seasonal influenza remains a priority, with the main intervention being annual immunisation.
Seasonal influenza vaccines have traditionally been trivalent inactivated vaccines containing haemagglutinin against the three main circulating types or subtypes: A (H1N1), A (H3N2), and B. In the UK, the vaccine is delivered mainly from October to December every year, with 14 million people vaccinated in 2017-18. Annual vaccine campaigns are the final stage of …