I spend my time infecting volunteers with influenza virus to better understand how vaccines and antivirals work. How well the flu vaccine works can vary from season to season and is dependent on the similarity or “match” between the circulating flu viruses and the strains in the flu vaccine itself.
Last year something went wrong with the flu vaccine and it was estimated to be effective in just 3% of cases, so people may wonder why they should bother this year. Vaccines are based on recommendations from the World Health Organization — production starts in the second quarter of the year ready for the vaccination campaign in the third quarter, so this takes a total of six months. A vaccine contains three or four killed flu viruses so, even when there is a less than an ideal match against one virus, the vaccine may protect against the others. However, last winter, the most important component of the vaccine did not match the specific strain of the virus.
Nick Phin, the director of the Centre for Infectious Disease at Public Health England, talking to BBC Radio 4’s Today programme, said: “We never know what strain is going to be hitting us… unfortunately there is nothing we could do. The vaccine had already been produced.”
He added: “What happened this year is unusual… this is the first time it has happened in a number of years to this extent… we do need to push for a better vaccine, one that gives protection against a wider range of strains so that we wouldn’t see this situation again.”
Estimates of the annual number of deaths attributable to flu in the UK vary, with an average of around 8,000 per year. Studies show that vaccination reduces flu-related hospitalisations among adults of all ages by 70% and by even more in people aged over 50 years. Vaccination helps protect women during pregnancy and their babies for up to six months after they are born, not to mention at-risk groups such as those with asthma or chronic health conditions and those aged over 65 years.
Children are the source of many flu infections and may quickly pass the virus to elderly relatives. Since 2013, children aged two and three years have been eligible for vaccination with a newly available live attenuated vaccine.
Unfortunately, it is believed that the mortality rate in the UK caused by the mismatch of the vaccine in 2014 increased by up to 50%, which demonstrates the clear need for a better vaccine with a lower risk of mismatch. However, what this also tells us is that when the flu vaccine is properly matched, it is effective in saving lives. Therefore, as healthcare professionals, we must promote the flu vaccine and encourage those in at-risk groups and children to get it, and explain why.