How does the flu vaccine work?

Gain a better understanding of how the flu vaccine works through our simple guide

The flu jab works by injecting you with a tiny amount of an inactive flu virus. In response to this, your body’s immune system makes proteins called antibodies to help fight what it thinks is an infection.

This helps you build immunity, so you’re less likely to catch the virus. There’s a small chance you can still get the flu after being vaccinated. Even if this happens, it’s usually milder and doesn’t last as long.

The nasal flu vaccine is slightly different in that it does contain a live type of the flu virus, but it’s been altered to make it weaker. It works in the same way as the flu jab.

Simply, the vaccine protects you from getting the flu. The flu is an uncomfortable experience for anyone, but it can also make you seriously ill. If you’re pregnant, over 65 or have a long-term health condition, you’re even more at risk from developing flu.

This doesn’t just protect you, it means you’re less likely to spread the virus to other people. So it’s even more important if you work with or are close to people who may be more vulnerable to flu complications.

The flu vaccine is very effective. It may be more or less effective depending on your age and the year. In the UK, the flu vaccine prevented 15 to 52% of flu cases between the years of 2015 and 2020.

The flu vaccine is generally more effective in preventing flu in children than in older adults. People over 65 may be offered a type of flu vaccine called the QIVe flu vaccine, which is more effective for them.

But even if you still catch the flu, getting vaccinated can prevent you from serious complications or hospitalisations. This is because if you do catch the flu after getting vaccinated, the illness is usually milder.

Generally, the flu vaccine lasts for about a year. So you should try to get a flu jab each year before the start of flu season, which usually starts in winter.

New strains of the flu virus emerge every year, so new vaccines are made to fight them. This is why you’ll need a new vaccination each year to stay protected against flu.

Work on the first flu vaccination began in 1931 in the USA. The first approved flu vaccines were developed by the US military in the 1940s and used to protect soldiers during World War 2.

The nasal flu vaccine often used for children was first approved in 2003 in the USA. Millions of children in the UK have been protected by the vaccine.