Nurseries are being urged to record the names of children who have not been vaccinated following outbreaks of measles across the country.
The National Day Nurseries Association is drafting new guidelines for its 1,600 members. Karen Walker, its strategic development director, said: "Our concern is growing. A nursery told me on Monday it had a child go down with measles. It sent a note home to all other parents warning them to look out for the symptoms, and other parents decided to keep their children home.
"Another nursery said parents had asked to be told which children were not vaccinated.
"We need to be responsible. Nurseries rely on herd immunity, so the more children who have not been vaccinated, the greater the risk."
Children at two nurseries in Streatham, south London, were tested last week after three contracted the disease. Another outbreak centred on a school in north London and four cases were confirmed on Tyneside.
Some nurseries are reportedly considering a ban on children who have not been vaccinated though Margaret Lochrie, chief executive of the Pre-school Learning Alliance, urged them not to panic.
"We are advising our pre-schools not to exclude children on the basis that they have not completed their vaccination programme," she said.
The immunisation rate has fallen well below the 95 per cent target which would offer "herd immunity" after a study by Dr Andrew Wakefield, at the Royal Free hospital in London, linked the combined jab with autism and bowel disease. The Government rejects his findings and is considering screening all pre-school children for autism to help understand the syndrome.
This week the chief medical officer, Sir Liam Donaldson, wrote to GPs giving them further information on MMR with which to lobby parents. TV broadcasts are also being planned, as part of a pound;3 million campaign. Dr Helen Zealley, an adviser to the Early Education charity, backed the vaccination campaign.
"Many parents can't remember the last serious measles outbreak but it left some children deaf or blind, or with serious neurological problems."