MMR jab immunity 'may slowly wane but is still highly effective against measles'

A vaccine that protects against measles has been shown to wane very slowly over time but still remains highly effective against the contagious disease, scientists have said.

More than 95% of people who have had two doses of the measles, mumps and rubella vaccine (MMR vaccine) – which was introduced in 1988 – are protected for life, findings published in the journal The Lancet Public Health show.

Data from the UK Health Security Agency (UKSHA) suggests a vast majority of measles cases in England are in unvaccinated children and young people, there has been also been an unexplained rise in infections among those who are double-vaccinated.

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A modelling study led by The London School of Hygiene & Tropical Medicine (LSHTM) suggests that the effectiveness of the MMR jab can very gradually decrease over time, by 0.04% each year after the second dose.

Scientists said this could partly explain why people who have been vaccinated are still getting measles.

But they added that the “slight waning” in MMR vaccine immunity is only apparent because uptake is lower than the 95% coverage target set by World Health Organisation (WHO), which is fuelling outbreaks.

The latest UKHSA figures show only 85% of under-fives in England have received two doses of MMR.

Adam Kucharski, professor of infectious disease epidemiology at LSHTM, said: “Measles is an infection which is highly transmissible.

“So although we have a highly effective vaccine, we need very high coverage to prevent transmission in communities and ensure that cases remain at low levels.

“Because we have had this drop-off in coverage in recent years, we have seen outbreaks of measles in England.”

Dr Alexis