The MMR (measles, mumps, rubella) vaccination programme which is usually given when a child is fifteen months old, has been found ineffective when given under a year.
It has discovered that the immune system is too immature to benefit from the vaccine; instead, most babies have natural immunity from their mothers, often passed on when it is still in the womb or through breastfeeding.
If the findings of the Californian study are accepted, it would mean that the first vaccinations given at six, nine and 12 months could not include the MMR.
Researchers studied the blood samples of 72 infants taken 12 weeks after vaccination. Maternal antibodies were found in over half the babies, but this declined to zero at one year.
Only 36 per cent of infants without maternal antibodies at six months of age had any protection from the vaccine, compared with 100 per cent of infants who were vaccinated at one year (JAMA, 1998; 280: 527-32).