Measles is steadily on the rise in the UK, and vaccination is dropping. Unless vaccination rates significantly improve, the city of London could face a measles outbreak of between 40,000 and 160,000 cases, according to mathematical calculations by the UK Health Security Agency (UKHSA). Experts warn an outbreak of this scale would lead to dozens of deaths and thousands of people hospitalized.

Measles, a highly contagious viral disease, is transmitted through the air when an infected individual coughs or sneezes. The initial symptoms of measles include a cough, runny nose, red eyes, and fever, followed by the appearance of a rash consisting of tiny red spots. The rash usually emerges on the head and then spreads throughout the body.

New data published by the UKHSA shows there’s been a steady increase in measles cases in the UK this year. Between January 1st and June 30th, a total of 128 cases were reported, compared to 54 in the whole of 2022 – with 66% of the cases detected in London. While the risk of a country epidemic is low, London faces a much higher risk.

“Measles can be a serious infection that can lead to complications, especially in young children and those with weakened immune systems. Due to longstanding sub-optimal vaccine uptake there is now a very real risk of seeing big outbreaks in London,” Vanessa Saliba, an epidemiologist consultant at UKHSA, said in a statement.

Measles growing risk

Measles can be prevented through the administration of the MMR vaccine, which provides protection against three diseases: measles, mumps, and rubella. It’s a safe and highly effective vaccine. Two doses offer approximately 97% effectiveness in preventing measles, while a single dose provides around 93% effectiveness.

London’s risk primarily stems from prolonged low vaccination rates, persisting over several years and exacerbated by the COVID-19 pandemic. UKHSA’s latest risk assessment suggests the R number, the number of people an infected person transmits the virus to, has exceeded, or is close to 1.0 – the point at which a virus can take off.

David Elliman, a consultant at Great Ormond Street Hospital, said the risk faced by London isn’t a surprise. “MMR rates in London have never reached satisfactory levels and have been falling slowly, but steadily, over the last 10 years. Uptake of all routine vaccines in London has always been lower than most of the rest of the UK,” he added.

In order to achieve herd immunity, the World Health Organization established a goal of 95% vaccination uptake. However, the UK currently falls significantly short of this target, with an uptake rate of the first dose for children aged two years at 85.6%. This figure is even lower in some areas of London, standing at just 69.5%, the UKHSA said.

The risk of a measles outbreak outside London is relatively low. However, there could be smaller outbreaks within certain populations. These include teenagers, young individuals, and those who have not received vaccination. Travelers, migrants, and communities such as the Charedi Orthodox Jewish community also face a higher risk. With income inequality on the rise and around 1 in 5 Brits living in poverty, such an epidemic could be devastating.

The UK’s National Health Service (NHS) has launched a national campaign to encourage more people to take the MMR vaccine, especially targeting those identified as at high risk. Children at primary school who missed one or two doses of the MMR vaccines are being offered to get up to date at school. Parents are being contacted by the NHS.

“These new data paint a harrowing picture of the risk to the capital of a measles outbreak,” Andre Pollard, director of the Oxford Vaccine Group, said. “We must not underestimate the seriousness of this message. If the scenarios modelled in London occur, an outbreak on this scale means that some families will be facing the death of a child.”