Is having the flu jab worth it?

By Lilian Anekwe

BMJ Group News

What do we know already?

In the UK, if you are aged 65 or over, or if you have health problems such as asthma, you are entitled to a free flu vaccine (also known as the flu jab) to protect against winter flu. From October 2014, the NHS in the UK will also offer the seasonal flu jab to children aged 2 to 17.

Every year in the UK:

• About 20 in 100 adults catch the flu
• About 5 in 100 children get the flu
• About 1 in 100 people are treated for flu in hospital

There has been a lot of research looking at whether the flu vaccine can reduce people’s risk of dying from the flu or having to go to hospital. One large summary of the research, called a systematic review, showed that if the vaccine was a good match for the most common types of flu virus in a season, the risk of getting flu would go down from 4 in 100 people who hadn’t been vaccinated to 1 in 100 people who had been vaccinated. However, this and other reviews have also warned that many studies into flu vaccines are of poor quality, and that they might overestimate how well vaccines work.

This latest review, by researchers at the University of Minnesota, looked at more than 12,000 studies dating back to 1936, as well as interviews with 88 vaccination experts. They also reviewed whether the vaccine that was available during the 2009 to 2010 winter flu season was effective.

What does the new study say?

From examining the studies, the researchers found that, for every 100 people who get the flu vaccination, between 70 and 90 will not get the flu that year.

But they found many of the studies reporting favourable results about the efficacy of the flu vaccine have been of poor quality or badly designed.

When they looked at the evidence for the flu vaccine that you take by injection, the researchers found that the vaccine protects around 59 out of 100 healthy adults. However, the evidence was inconsistent for it protecting children 2 to 17 years of age, or adults aged 65 years or older.

When the researchers looked at a newer flu vaccine that you take by nasal spray, they found that it protects around 83 in 100 young children aged 6 months to 7 years old. However, the evidence was inconsistent for it protecting people aged 8 to 59.

How reliable is the research?

This was a comprehensive review, but it has not been published in an academic journal, so we can’t be sure how reliable the evidence is.

What does this mean for me?

The conclusions of this review relate to the vaccination programme in the US, which includes people of different ages, and we don’t know if they would apply here. The review finds that the evidence for the flu jab is inconsistent and inconclusive because the studies are of poor-quality. But this doesn’t mean that the programme doesn’t work, which is what some newspaper headlines have claimed. The researchers say that, for now, the annual flu vaccination campaign is the best way we have to protect people from the risks of complications and death from the flu.