UK measles outbreaks: why are cases rising and vaccination rates falling?

With outbreaks of measles occurring across England and Wales, we take a look at what is behind the rise, and what must be done to stop it.

What is measles?

Measles is a highly infectious virus that can cause serious illness, such as inflammation of the brain.

Related: Surge in measles cases prompts UK to declare national health incident

“Even in high-income countries like the UK, about 1 in 5,000 die from the infection,” said Prof Helen Bedford of UCL Great Ormond Street Institute of Child Health, adding that measles is often more severe in adults.

Measles is associated with cold-like symptoms and a high temperature, followed by a rash that usually starts on the face but can spread over the whole body.

“Apart from managing the symptoms of measles, there is no treatment,” said Bedford.

What is the current situation?

Cases of measles are rising. According to data from the UK Health Security Agency, there were 1,603 suspected cases in England and Wales in 2023, compared with 735 in 2022, 360 in 2021, and 695 in 2020. Figures were even higher before the Covid pandemic, with 2,422 suspected in 2019 and 2,608 in 2018, a situation that also caused alarm.

Outbreaks have occurred around England in recent months, including in London, with the West Midlands experiencing cases at their highest level since the mid-1990s. Birmingham children’s hospital reported seeing more than 50 children needing treatment in the last month.

Don’t we have a vaccine?

Yes, it is very effective (about 99% after two doses) and free. It is given as part of the MMR jab, with the first dose typically given aged one, and the second at three years and four months. However teenagers and adults who missed out can also get vaccinated.

Vaccination rates of about 95% would give the entire population herd immunity, meaning the few who are unvaccinated – for example young babies – are protected because those around them are immune to measles.

So what is going on?

The problem is that vaccination rates in some parts of the country are not high enough to prevent the virus from spreading. Data for 2022-23 shows only 84.5% of children in England receive the second MMR vaccine dose by five years of age, while in London and Birmingham a quarter of five-year-olds have not had two doses of MMR.

Experts have put this down to a number of reasons, including some parents not realising the NHS was still offering MMR vaccinations during the pandemic, not realising how serious measles can be, having problems accessing appointments, or being swayed by anti-vaccine conspiracy theories.

Among the most influential pieces of misinformation was the 1998 claim by Andrew Wakefield that the MMR jab could be linked to autism – a theory that has since been comprehensively debunked.

Paul Hunter, a professor in medicine at the University of East Anglia, noted a UK study from 2019 that found that people born between 1998 and 2004 – the period after the Wakefield paper – were not only the most susceptible to measles, but also had the highest incidence.

However the latest data for England reveals that the majority of the 209 laboratory-confirmed cases of measles between 1 January 2023 and 30 November 2023 was in children under 10, reflecting the decline in vaccination rates.

Are other factors at play?

Adam Finn, a professor of paediatrics at the University of Bristol, said the closure of schools, shops and other settings during the Covid pandemic would have reduced transmission of measles. Combined with reduced vaccination rates, this meant that once Covid restrictions were eased, there was a larger pool of susceptible people.

“That of course creates a situation where you will then get more cases when the virus is around,” said Finn.

Where does this leave us?

In brief, the UK has returned to a situation that was already bad pre-pandemic.

“We’ve been seeing hundreds of cases now which has been ramping up over a period of years,” said Finn. “I think it’s right that we should be worried because it’s completely preventable.”

Indeed in 2016 the UK was declared measles-free. But that status has not been maintained.

Hunter said that with vaccine uptake still declining in young children, he would expect measles to be an increasing problem in the coming years.

Bedford also raised concerns. “Measles is nasty: if we do have large outbreaks it is inevitable we will have deaths,” she said. “But aside from the risk to children, it will also put additional pressure on the NHS at its most pressured time.”

What should be done?

Experts say it is crucial to encourage parents to have their children vaccinated against measles.

But Finn added that funding was vital for proactive approaches, such as chasing people up to attend appointments.

“A big part of this is just yet another legacy of a decade of underinvestment [in the NHS],” he said.