Toddlers in some Liverpool areas are at risk of catching deadly diseases after a fall in vaccine uptake.
A report to the council's health and social care select committee warns that 'further investigation' is needed after a drop over the last year in the proportion of under-5s being properly vaccinated against diseases like measles.
The report says that vaccination levels in the city overall are still either 'good' or 'very good' but variation between wards has the potential to leave children at risk.
It says: "During the last 12 months, there appears to be a reduction in the uptake of vaccination, particularly in the under 5 year olds and further investigation is needed to establish any reasons for this."
Public health experts recommend that 95% of the population be vaccinated against a disease.
In Central, Picton and Princes Park , less than 80% of children have had the two MMR jabs by their fifth birthday.
The jab protects against measles, mumps and rubella, which can all cause serious complications among young children.
The report doesn't pinpoint one cause for the fall in vaccine uptake but says problems within the NHS and the increased popularity of anti-vaccination movements could be factors.
Only 86.3% of five year olds across the city got their second dose of the MMR jab in the final three months of last year.
When vaccination uptake drops too far 'herd immunity', which gives protection even to unvaccinated people, ceases to have an effect, making disease outbreaks more likely.
Aside from the MMR jab, uptake of the HPV and Meningitis ACWY vaccines, which are both given to teenagers, was also down.
However Liverpool still has some of the best vaccine uptake levels among the UK's biggest cities.
