http://news.independent.co.uk/uk/health/story.jsp?story=66136

New strains of measles may resist vaccination

By Charles Arthur, Technology Editor

12 April 2001

New, more lethal strains of measles could strike unless fresh efforts are made to increase levels of vaccination around the world, doctors have warned.

Mutant variants of the virus are now circulating in Africa. They are resistant to half of the antibodies that humans produce when vaccinated, according to research by Claude Muller of the National Health Laboratory in Luxembourg. Although the vaccine now in use is still effective against existing strains, Dr Muller ­ an adviser to the World Health Organisation (WHO) ­ warned New Scientist magazine that "we know this family of viruses mutates rapidly".

That could lead to super-strains of the virus that would be resistant to the present vaccine, which contains only a single strain of the virus.

In Britain, vaccination rates against measles have dropped noticeably in the past five years, leading to a doubling in the number of children without vaccination. Figures collected by the Public Health Laboratory Service (PHLS) show that the proportion of infants being immunised against measles (as well as mumps and rubella through the MMR vaccination) fell from 92.5 per cent to 87 per cent as a dispute grew over whether the MMR jab caused autism.

Though the vaccination rate has levelled out at 88 per cent after a Government publicity campaign to encourage parents to protect their children, health chiefs are still concerned that it is heading towards 80 per cent ­ the level at which an uncontrollable epidemic could occur.

The WHO is concerned that measles, like TB, could make a fatal return if it is not stamped out through vaccination, as smallpox was. The increasing ease with which human viruses can spread through international travel means that infectious diseases in one country can quickly spread to another. The WHO, which had wanted to eradicate measles by 2005, now suggests that the death toll should be halved.

Measles is one of the most dangerous childhood diseases: nearly one million people die worldwide of measles every year, and the survivors may be left with permanent injuries, including brain damage. However, only 75 per cent of all the world's children have been vaccinated against the illness, compared with a WHO target announced three years ago of 90 per cent.

A spokeswoman for the PHLS said: "There was a major outbreak in Dublin last summer which did lead to several deaths." Dr Muller said the measles viruses now circulating would have less chance to evolve into resistant ones if doctors acted. "We have a window of opportunity," he told New Scientist.

Bjorn Melgaard, the WHO's head of vaccines, said that the revised target of halving deaths was "feasible," adding: "But we may not be able to eradicate measles. And it might not even be worth it to try."