"Flu kills an average of 8,000 people in England every year and can be particularly serious in very young children, pregnant women, adults aged 65 and over and those with health problems because they tend to have weaker immune systems. For the first time, all children will be given a nasal spray in primary schools, which will help them immunise against the four virus strains contained in the vaccine."
https://www.wired.co.uk/article/nhs-england-flu-vaccines