MMR vaccination catch-up programmes have resulted in more than 95% of GP practices across England ordering extra doses of the vaccine.
This amounts to an additional 200,000 doses for surgery nurses to inject into children and teenagers who remain unvaccinated.
The programme, run by Public Health England (PHE), NHS England and the Department of Health, hopes to stop measles outbreaks by vaccinating as many 10 to 16-year-olds as it can.
This age group is the most in danger of measles because of a drop in MMR vaccinations in the late 1990s and early 2000s.
This coincided with widespread fears about the discredited link between autism and the three-in-one vaccine.
The catch-up programme aims to ensure that a minimum of 95% of 10 to 16-year-olds - or an estimated 300,000 children - have received at least one MMR jab.
The programme is also keen to immunise another 333,000 in this age group who require a second dose of MMR to give them full protection, and a further 333,000 children below and above this age band who need another jab.
Latest statistics by PHE show numbers of confirmed measles cases in England remain high.
There was 288 cases in April, compared to 175 in the same month 12 months ago, bringing the total amount so far this year to 962.
Head of immunisation at PHE, Dr Mary Ramsay, said: “Our ambition is to vaccinate 95% of 10-16 year olds at risk in time for the next school year and so the number of extra doses ordered by most GP practices is very encouraging.”
Dr Ramsay added that the message to parents who believe that their child may not be fully immunised is to check today and book an appointment with your doctor.
Are you able to Speak Out Safely? Sign our petition to put pressure on your trust to support an open and transparent NHS.