Cases of measles in London up on 2012 figures
The number of cases of measles in London between January and March has doubled compared to the same period in 2012, health officials have said.
Confirmed cases increased from 34 in 2012 to 68 this year, with the borough of Hackney having 28 cases.
There are concerns about the city's low uptake of immunisations and its dense population causing measles to spread.
The Department of Health (DoH) which provided the statistics advised parents to get their children vaccinated.
Prof David Salisbury, director of immunisation for the department, said: "You have to prevent measles and that means we need to get ahead before we have got large numbers of cases and large outbreaks occurring."
He added that parents with children who had not had the MMR (measles, mumps and rubella) jab should contact their GP.
Figures released also show that cases had been reported across London including four in Greenwich, 10 in Bromley, seven in Barnet and two in Bexley this year.
They also revealed the uptake of the MMR jab in London was below the national average of 86%, with Lewisham and Camden boroughs at just under 70%.
London GP, Dr Lawrence Buckman, said: "There would be large numbers of 10-16 year-olds who would go down with measles and about one in five would end up in hospital."
He added: "Parents do have a choice and have a right to say 'I don't want this done to my child' [but] I believe they should not exercise that right. This is an avoidable problem."
Nationally about a million children and teenagers who have not had either one or two doses of the MMR vaccine will be offered catch-up vaccinations, which the London Assembly said it welcomed.