The proportion of children being vaccinated against measles, mumps and rubella (MMR) has fallen for the first time since 2007/08.
Some 92.3% of children were vaccinated with the first dose of MMR by their second birthday, down from 92.7% the year before, data from the Health and Social Care Information Centre (HSCIC) showed .
Despite the fact MMR uptake has been on the rise up until now, the percentage of children vaccinated still falls short of the World Health Organisation (WHO) target of 95% needed for herd immunity.
MMR coverage was highest in the North East of England (95.2%) and lowest in London (87.3%).
Some 88.6% of children had received both doses of MMR by their fifth birthday, a slight increase on the previous year although still well below the WHO target.
By age five, some 94.4% of children had received their first dose of MMR, also below the WHO target.
Uptake of the MMR vaccine fell heavily in the late 1990s following the publication by Dr Andrew Wakefield of research suggesting a possible link between the vaccine and autism.
Experts have widely discredited his study and he was struck off the medical register in 2010.
The HSCIC report said several factors could have led to a rise in MMR uptake in recent years, including campaigns to target unvaccinated teenagers and a recommendation that MMR is offered on the same day as other vaccines.
Others suggested the new drop could be due to anomalies in the data collection or the fact fewer children were being given the vaccine.
Overall, the figures for most routine childhood vaccinations at ages one and two fell slightly in 2014/15 for the second consecutive year.
But there were small increases in the numbers vaccinated by the age of five.
The flu vaccine was also offered to all children aged two, three and four during the winter of 2014/15.
GPs were encouraged to ensure that coverage of the vaccine in these children was as high as possible.
New figures showed coverage for all two-years-olds in England was 38.5%, 41.3% among three-year-olds and 32.9% among four-year-olds.
Among adults aged 65 and over, flu vaccine uptake was 72.7% in 2014/15, down on the 73.2% the year before, and below the WHO target of 75%.
Dr David Elliman, immunisation expert for the Royal College of Paediatrics and Child Health, said: "It is disappointing that uptake of NHS immunisations have not continued to rise, however the falls are very small.
"This could be read as children not receiving the vaccination or, alternatively, it could be a lack of data collection linked to considerable pressures on staff working in the NHS.
"Immunisation is vitally important if we are to protect child health both here in the UK and internationally in the long-term. I would therefore urge all parents to contact their GP if they are unsure whether their child is up-to-date with their vaccinations."
Dr Mary Ramsay, head of immunisation at Public Health England, said: "England has a world class national immunisation programme which is constantly reviewed and updated to reflect the changing nature of infectious diseases, and the annual data shows continued high uptake of all routine vaccinations in children aged up to five years."
She added: "We urge all parents to check that their children are up to date with their vaccinations and to contact their GP as soon as possible if they are unsure so that no child misses out."