A new study, published online by the Journal of Epidemiology and Infection, found that a third of children given one MMR dose, and 15 per cent of those given two, had low levels of mumps antibodies. Experts from the Health Protection Agency have described the results as cause for concern.

The findings, which come as mumps rates continue an alarming rise, have prompted GPs to call for a change in the schedule for MMR, which is given to protect against measles, mumps and rubella. Children are given one combined jab at 13 months and a second between the ages of 3½ and 5.

The Royal College of General Practitioners (RCGP) said that consideration should be given to bringing the second dose forward to shorten the period during which children are protected with only one dose. The Government’s Joint Committee on Vaccination and Immunisation said that it would also be considering the implications of the new research for the vaccine programme. The study analysed serum samples from 3,445 patients aged from 1 to 69. In children born between 1986 and 1990, who would be expected to have received one dose of MMR as part of routine vaccination, 34 per cent were found to have low levels of mumps antibodies — indicating potential lack of protection. Of those born between 1991 and 1995, who should have had two doses, 15 per cent were found to have low antibody levels.

Recently suspected cases of mumps have surged to about 2,000 a week. The rise is believed to be the result of young adults, who were too old to be routinely offered the MMR vaccine when it was introduced in 1988, mixing in large numbers at university. Students are particularly at risk because the infection spreads easily in such environments. It is estimated that about 30 per cent of first-year students have not had two doses of MMR vaccine. The latest findings will cause more concern to parents averse to giving children multiple jabs early in life. The issue became prominent after unfounded claims that the triple measles, mumps and rubella vaccine was linked to autism.

Richard Pebody, a researcher on the study and consultant epidemiologist, told the medical magazine Pulse that the agency was undertaking further work assessing the effectiveness of two doses, which was a “priority” given the recent mumps outbreaks.

George Kassianos, the RCGP immunisation spokesman, said: “The second dose of MMR vaccine in our childhood immunisation programme should be transferred nearer to the second year of life.”

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