Hundreds of youngsters in the area were not fully vaccinated against the trio of potentially life-threatening diseases by their fifth birthday last year, according to the latest childhood vaccination statistics.
The MMR jab protects against measles, mumps and rubella, highly infectious conditions which can have life-changing consequences.
For a child to be fully protected, they should receive two vaccinations, the first at the age of one and the second when they are three.
But NHS Digital figures show 86% of children in Peterborough were fully vaccinated by their fifth birthday in 2020-21 – below the 95% target set by the World Health Organisation.
It meant 450 children did not receive both doses of the MMR jab by age five.
The latest figures suggest significant disparities in vaccine uptake across local authority areas, with 96% of five-year-olds fully vaccinated in County Durham compared to 60% in Camden.
Measles, mumps and rubella can easily spread between unvaccinated people and can lead to serious problems including meningitis, hearing loss and problems during pregnancy.
Dr Vanessa Saliba, from the UK Health Security Agency, said anyone without two doses of the vaccination remained at risk.
She said coverage had fallen nationally due to the coronavirus pandemic, increasing the risk of a resurgence of the diseases.
Dr Saliba added: “It’s essential that parents take up the offer of MMR for their children.
“If your child has missed one or both of their MMR vaccinations, contact your GP surgery to arrange an appointment as soon as possible – it is never too late to catch up.”
Last year, 88% of infants in Peterborough had their first jab before the age of two, suggesting around 326 babies did not receive the routine immunisation.
Across England, 90% of two-year-olds and 94% of five-year-olds had received the initial vaccine in 2020-21, meaning both proportions were slightly down from the year before.
Around 87% of five-year-olds had received both jabs by their fifth birthday.
An NHS spokeswoman urged parents to check their child’s medical records and ensure immunisations were up to date, adding: “It’s vital that parents ensure their children are fully protected with this jab – which can ultimately save a child’s life.”
The recently launched Office for Health Improvement and Disparities, part of the Government’s Department of Health and Social Care, is working to reduce health disparities and improve access to services.