Health officials are scrambling to stem an alarming tide of measles across England, after a child was confirmed to have died.
More than 2,000 cases have already been recorded in 2024 — the biggest outbreak in over a decade.
But as few as half of children have had both doses of the measles, mumps and rubella (MMR) vaccine — credited with saving the lives of tens of thousands of kids — in parts of London.
Similarly low levels are also seen in Liverpool, Manchester and Birmingham.
The child, who has not been identified and had 'other medical conditions', is believed to have died in the first quarter of the year.
UK Health Security Agency (UKHSA) surveillance figures show another 78 cases had been confirmed in England in the past fortnight.
It takes the total number of cases across the country this year up to 2,465.
Children aged 10 or younger account for almost two thirds (1,513) of these.
Health officials said the West Midlands remains at the heart of the outbreak, with the 358 cases centred around the Birmingham area in 2024.
London followed, logging 172 in Lambeth and 145 in Wandsworth respectively, this year.
Parents have been urged to check their kids have had both doses of the jab.
Without the two MMR jabs, experts warn they risk becoming seriously ill from the extremely contagious virus and passing it on to others.
Measles, which produces flu-like symptoms as well as the tell-tale rash, can cause very serious and even fatal health complications if it spreads to the lungs or the brain.
One in five children who get infected will be hospitalised, according to estimates, with one in 15 developing serious complications like meningitis or sepsis.
Dr Vanessa Saliba, consultant epidemiologist, at the UKHSA said: 'Measles is preventable with two doses of the MMR vaccine, but many thousands of children around the country are still not vaccinated and may be at risk of serious illness or life-long complications.
'No parent wants this for their child. Don't put it off, please act today so we can ensure that all children are given the best protection.
'With measles continuing to circulate in England and sadly one death in a young person, ensuring timely vaccination has never been more important.
'The MMR jab offers the best protection against measles and importantly vaccination is also about not spreading the disease to others who may be more vulnerable.
'Our thoughts and condolences are with the family who have so tragically lost their child.'
Two doses of the MMR vaccine offer up to 99 per cent protection against the trio of illnesses, which can lead to meningitis, hearing loss and problems during pregnancy.
At least 95 per cent of the population needs to be vaccinated to prevent outbreaks, under public health guidance.
But nationally, the proportion of five-year-olds who are fully jabbed has fallen to 84.5 per cent — the lowest in more than a decade.
Latest NHS Digital also shows up to four in ten children in parts of England haven't had both MMR jabs by the time they turn five.
Just 56.3 per cent of youngsters that age in Hackney, east London, were fully-protected against measles, mumps and rubella in 2022/23.
After Hackney came Camden (63.6 per cent) and Enfield (64.8 per cent).
Outside of London, the lowest uptake rates for both doses among five year olds were logged in Liverpool (73.6 per cent), Manchester (74.5 per cent) and Birmingham (75.1 per cent).
Uptake of the MMR jab collapsed in the late 90s and early 2000s in the wake of a 1998 study by the now discredited medic Andrew Wakefield which falsely linked the jabs to autism.
Last month NHS chiefs renewed calls to parents to ensure their children had caught up on any missed vaccinations before they head back to school, amid fears of a rise in measles cases.
The health service says people should check their vaccination history and catch-up on any missed doses from their GP or a pop-up clinic.
Major measles outbreaks in the West Midlands, North West and London within the last year have seen cases soar to a 10-year-high.