At least 34 children have been infected by a “fast spreading” measles outbreak in north London, leaving several requiring hospital treatment.
Over 60 suspected cases of the potentially fatal illness have been reported by seven schools and one nursery in Enfield, the Sunday Times first reported.
A local GP surgery said one in five children who had contracted the illness had been hospitalised and “had not been fully immunised”.
Measles is a highly contagious airborne illness caused by a virus that can trigger severe complications and prove fatal.
Families have been urged to ensure their children are up to date with their vaccinations, which offers the most effective protection against infection and transmission.
The UK Health Security Agency confirmed 34 laboratory-verified measles infections in Enfield between the start of the year and 9 February.
Enfield's director of public health is writing to every parent in the area as authorities attempt to contain the disease's spread throughout London.
Dudu Sher-Arami has written to parents in the borough warning that unvaccinated children could be “excluded” for 21 days if they come into contact with an infected person, the Telegraph has reported.
“If your child is identified as being a close contact of a person with measles and they are unvaccinated they may be excluded from school for 21 days,” the letter warned.
It is understood in such a scenerio pupils would be asked to learn from home.
The council has called on anyone who thinks they have measles to “isolate”.
“If you think you have the measles, you should isolate yourself if possible, and especially from those at greatest risk, including children under the age of one year, people with weakened immune systems and unvaccinated pregnant women,” a spokesman said.
A number of clatch-up clinics are offering free vaccinations across London, which parents can book onto. Some of the locations include Havering, Tower Hamlets, Barnet, Camden, Newham and Islington.
A notice published by the NHS Ordnance Unity Centre For Health GP surgery warned of a "fast spreading measles outbreak in several schools across Enfield".
The GP surgery added: "Infections have been confirmed across at least seven schools in Enfield and Haringey and it is spreading.
"During this recent outbreak, one in five children have been hospitalised due to measles and all of them had not been fully immunised.
"Parents should ensure that their children are up-to-date with all their immunisations."
The disease can be prevented through vaccination, available as part of the Measles, Mumps, Rubella, Varicella injection.
However, Enfield reportedly has among the country's poorest uptake rates for the two-dose vaccine.
Temporary vaccination centres have been established in schools across the borough in an effort to boost immunisation levels.
Enfield Council confirmed it was "working closely with the UK Health Security Agency, the NHS and local partners to respond to a confirmed outbreak of measles in the borough".
Cabinet member for health and social care, Councillor Alev Cazimoglu, said: "We are following national public health guidance to manage the situation, protecting residents and limiting further spread.
"The current outbreak has mainly affected children and some have required additional care with a short stay in hospital. Measles is one of the most infectious known diseases. It is approximately six times more infectious than Covid-19.
"Catching the measles is entirely preventable, but it spreads extremely quickly where vaccination levels are low. By checking your family's vaccination status and taking up the free NHS vaccine, you are protecting not only yourselves but also vulnerable members of our community.
"Vaccination is the most effective way to protect yourself and your family. We urge everyone who is not fully vaccinated to act now."
Last month, the World Health Organisation declared the UK no longer qualifies as having eliminated measles.
UK Health Security Agency data shows 91.9 per cent of five-year-olds received one MMR (measles, mumps and rubella) vaccine dose in 2024-25.
This represents the lowest coverage level since 2010-2011.
WHO recommends at least 95 per cent of children receive vaccine doses for each disease to establish herd immunity.
