There have been more than 300 suspected cases of measles amid a major outbreak of the virus in London, a leaked official document has shown.
An internal report from the UK Health Security Agency shows there have been 340 suspected cases of measles in the capital since the start of 2026.
The report, marked “official sensitive”, also reveals that 34 confirmed cases have been from just one school in Enfield, north London, between 20 January and 7 February this year.
The new figures, seen by The Independent, come after health officials raised concerns over an outbreak in northeast London where vaccination rates for measles are in decline. A child also died with measles in Liverpool last year, while the UK recently lost its measles elimination status.
In the most recent public update on Thursday, UKHSA said there have been 104 measles cases in London, including 71 confirmed cases across Enfield and Haringey.
However, the internal update to health professionals revealed that, of 340 suspected cases, 123 had been confirmed. The report said 57 of those were “probable” cases and 117 were “possible”.
Currently, children in the UK are offered the first dose of the measles, mumps, rubella, and varicella vaccine (MMRV) at 12 months, and a second dose at 18 months.
Dr Yimmy Chow, London region deputy director for UK Health Security Agency said in a statement to The Independent: “The measles outbreak in north London continues and while children remain unvaccinated, the risk of it spreading to other areas remains a real threat.
“Some parents today will be unaware of the terrible harm measles caused to so many children before the introduction of a vaccine. Measles can cause pneumonia, meningitis, blindness, seizures and tragically sometimes death. Every year we see children in hospital suffering needlessly, sometimes leading to long term complications.
“With a disease as infectious as measles, it will find those unvaccinated - there is no room for complacency.”
According to the internal UKHSA report, the majority of cases detected in London between 27 January and 24 February were in children aged between one and four, with 37 cases confirmed for this age group. There were 22 cases in children aged between 5 and 11. Most of the cases – 42 – over the same period were in children living in the most deprived areas of London.
Separate data in the report showed that, between 1 January 2024 and 23 February 2026, there have been 1,117 cases of measles in England, with 597 in London, 141 in the North West and 109 in the West Midlands.
The only part of the report that focused on vaccination rate was regarding cases between January 2025 and February this year. According to the report, 78 per cent of children aged 1 to 4 were unvaccinated, alongside 90 per cent of cases in children aged 5 to 11.
In a comment on the public UKHSA figures, Dr Josephine Sauvage, local GP and chief medical officer of the North Central London Integrated Care Board, said: “It is obviously concerning that cases are still rising, but there is something we can all do to protect our loved ones and ourselves, which is to get the vaccine.
“The vaccine is proven over decades to be safe, effective and the best way to protect your child and your wider family.
“We want to thank local GPs, nurses, healthcare professionals and trust colleagues across the NHS who are continuing to work extremely hard to respond.
“GP practices are continuing to contact unvaccinated patients, offering additional appointments, including out-of-hours clinics, to make it as easy as possible for families to get protected.”
Earlier this year, the UK lost its measles elimination status due to rates of vaccination not meeting the World Health Organisation’s recommendation that at least 95 per cent of children should receive vaccine doses for each illness to achieve herd immunity.
Uptake of the MMRV vaccine in the UK is at record lows. In areas such as Hackney, just 65.3 per cent of two-year-olds have received their jab and just 64.3 per cent of five-year-olds in Enfield had received both doses of the vaccine in 2024/25 – one of the lowest rates in the country.
Dr Sauvage added: “If your child is not up to date, please contact your GP practice to book an appointment. If you’re not registered with a GP, you can do so quickly and easily, or attend one of the local catch-up vaccination clinics.”
This article was updated at 18:30 with a comment from UKHSA.
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