How many children are not fully vaccinated against measles in England? Period and cohort analysis of primary care data to inform policy and practice

PI Title: Nicola Firman

Lead member: QMUL

Why do we need this research?
Measles is the most contagious infectious disease. The measles, mumps and rubella (MMR) vaccination is the only effective and safe public health measure to prevent infection. Children are eligible for two doses of the vaccine between 12 months and five years of age, yet in England, just 85% of children are fully vaccinated by their fifth birthday. In recent years, this
percentage has decreased across the whole of England, and there is significant geographic variation in vaccination uptake.
This low percentage has undoubtedly contributed to recent outbreaks of measles in England, where there have been 2,601 reported cases between January and November 2024 alone.

What do we want to find out?
We want to find out how many children are only partially (only having received one of the two MMR doses), or not at all vaccinated, against MMR. We want to know if the number of partially- or non-vaccinated children has changed over time from 2015 to 2025, and with each new group of children born since 2015. We also want to know how long it takes, on average, between becoming eligible for each MMR vaccine to receiving it, and if this length of time has changed over time.
We also want to investigate if MMR catch-up campaigns have had any impact on the number of partially- and nonvaccinated children.

What will we do?
We will count the number of partially- and non-vaccinated children to see if changes in the number of children who are partially- or non-vaccinated are related to events that affect many people at a particular point in time (the period effect), or are related to experiences that people had at a particular age (the cohort effect). Using statistical models, we will estimate how long it takes, on average for children to receive one or two doses of the MMR vaccination, and see if this is influenced by when children were born or the year they became eligible for vaccination. We will map the timing of MMR catch-up campaigns to our period and birth cohorts to estimate the impact of these campaigns on improving vaccination uptake.
Throughout the project, we will talk to parents about their experiences of messaging received during catch-up campaigns, and see if they have additional suggestions for ways of communicating.