While confidence in the UK's vaccination programme remains high, with uptake exceeding 90 per cent for most childhood immunisations, there has been a small but steady decline in coverage in recent years.
Mr Johnson set out the plans to improve vaccination rates - including for the measles, mumps and rubella jab (MMR) - on a visit to a hospital in Cornwall (left).
The MMR jab vaccination rate has risen in recent years in Norfolk, up from a low of 87.5pc of children having their first dose by the age of two in 2010/11.
The first dose is usually given to babies at a year old, the second dose before they go to school.
Two doses of the vaccine leaves 99% of people protected - the majority of new measles cases have been in people who are not vaccinated. PHE's catch-up call for primary school starters follows the issue of a new GP contract from NHS England and Improvement which also encourages 10 and 11 year olds to be caught up with any missing MMR vaccinations prior to them reaching secondary school age.
The United Kingdom says it will take steps to halt the spread of misinformation about vaccines as a result of losing its "measles-free" status after the highly infectious disease was declared eliminated in the country three years ago.
Furthermore, the same strain of measles virus (called B3 Dublin) was detected for more than 12 months across 2017 and 2018, the body said. We've seen outbreaks of this disease in the East Midlands in the past year and we're continuing to see outbreaks of the disease occurring in communities across the country, many linked to visiting European countries over the summer holidays.
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He said: "It's a real concern that so many young children in our region could be starting school without the full protection that the NHS childhood immunisation programme offers for free".
She said: 'We know that vaccinations are an incredibly good way of protecting large numbers of the population.
Others claim the vaccine doesn't work - but after the introduction of MMR rates of measles had dropped, from 86,001 cases in 1988 to just 3,728 reported a decade later.
Despite this, the prime minister has committed to discussing with social media companies how they can help to disseminate accurate information about vaccines, while also promising to update advice on the NHS website to address misleading information about the dangers of vaccines.
A lot of the under-immunisation we're seeing is not because parents don't want the vaccine, it's simply because they've not got round to it or they can't make an appointment easily.
Health Secretary Matt Hancock said: "It's easy to forget how devastating measles can be, precisely because vaccines are so effective at preventing it in the first place".
Measles is a highly contagious and risky infection.
Measles, which is nearly entirely preventable with two doses of vaccine, is making a comeback globally.