A quarter of children in London are not vaccinated against measles as new figures show a sharp rise in cases. Out of 231 new cases in England 149 were in the capital.
Public Health England says two doses of the MMR vaccine need to be given to protect against Measles, Mumps and Rubella.
The first dose is usually given to babies at a year old, the second dose before they go to school.
But figures show here in London almost 30,000 children haven't had that follow-up jab.
Today the Prime minister called for urgent action to take on the anti-vaccination movement.
Social media companies will also be called to a summit to discuss how they can stop the spread of misinformation online and doctors ordered to help ensure all under 25s are fully immunised.
Measles signs and symptoms:
- cold-like symptoms, such as a runny nose, sneezing, and a cough
- sore, red eyes that may be sensitive to light
- a high temperature (fever), which may reach around 40°C (104°F)
- a few days later, a red-brown blotchy rash will appear. This usually starts on the head or upper neck, before spreading outwards to the rest of the body
- Symptoms usually resolve in about 7 to 10 days. Complications include pneumonia, ear infections, brain inflammation (encephalitis) and even death