Extra MMR vaccines have been ordered by 95% of practices in England in preparation for the government's catch-up programme.
The programme, run by Public Health England (PHE) aims to prevent measles outbreaks by vaccinating at least 95% of 10-16 year olds before school starts in September.
Due to the fall in coverage in the late 1990s and early 2000s because of a discredited link between autism and the vaccine, this age group is most at risk.
Confirmed measles cases in England are still high with 288 cases in April (compated to 175 last year). The total number of cases this year is 962.
However, MMR coverage among 5 year olds in England is at its highest ever recorded levels, with 94% receiving 1 dose and 90% receiving 2 doses.
Dr Mary Ramsay, Head of Immunisation at PHE, said: “The number of extra doses ordered by most GP practices is very encouraging.
“We are getting regular feedback from the local NHS teams about what is happening on the ground and are encouraged by the very high levels of involvement by GP practices across England.
“We will shortly be getting results from a new monitoring system that will tell us the number of vaccines received by children.”
In some areas affected by recent local outbreaks, such as the North East and North West, the NHS had already started to run campaigns in schools.
In Teesside for example, school based vaccination clinics have been held in over 120 schools, vaccinating more than 2,000 primary and secondary school age children, and in Greater Manchester 32 schools have initiated schools based vaccination programmes, reaching 1,200 children.