MMR jabs should be given earlier because infants are vulnerable to measles for several months before their first vaccination, researchers say.
A team from the University of Antwerp, Belgium, found that infants lose maternal antibodies within three months of birth. This leaves them with no immunity until their first MMR vaccination, usually at 13 months, the researchers said.
The findings support the case for earlier vaccination, if research proves effectiveness at nine months or earlier, the researchers said. A follow-up dose could then be given at 15-24 months, they added.
Hertfordshire GPSI in travel medicine Dr Michael Ingram said earlier vaccination may become necessary if herd immunity falls to unacceptable levels in the community.
The researchers also advised authorities to consider vaccinating young infants travelling to endemic areas.
Dr Ingram said: 'If people are going to endemic areas and taking young children they should contact their GP or health advisory board.'
The researchers monitored the level of measles antibodies in 207 pregnant women from week 36 of pregnancy to 12 months after birth.
After six months, 99 per cent of infants of vaccinated women and 95 per cent of infants born to naturally immune women had lost maternal antibodies.
The researchers said the data 'strengthen the need for timely administration of a first dose of measles-containing vaccine '.
Early vaccination should also be considered in the event of an epidemic, they added.
Last year there were 1,144 confirmed cases of measles in the UK compared with 78 in 2005.
The Health Protection Agency issued a plea for parents to give their children the MMR vaccine following a sharp rise in early 2009.