Across most of the Americas, the measles vaccination rate is now higher than 80 per cent. The WHO estimates that a 95 per cent vaccination rate is necessary for full national immunity. But PAHO officials hope that if vaccination levels can be maintained or improved, they will be sufficient to keep a check on any future outbreak caused by an infected visitor to the continent.

The success of the programme is partly down to price cuts in measles vaccines, now down to about 10 cents per shot. It will give hope to a recently launched measles vaccination initiative in Africa - the last major stronghold of infection - where one child dies from the disease every minute. The achievement also suggests that global measles eradication is possible, says a PAHO vaccination expert.

Measles is one of the most infectious known diseases. It remains the leading cause of death due to an illness that can be prevented with a vaccine. In 1994, delegates at a Pan American Sanitary Conference agreed a three-stage attack on the virus, with the aim of stopping locally transmitted infections in the region by 2000.

Rapid spread
 

The first stage was to vaccinate all children aged between nine months and 14 years. The next stage involved routine vaccination of all children aged over one year. And the final stage was to mass-vaccinate children aged under four every four years, in an attempt to maintain widespread protection.

In 1996, the number of cases in the Americas had dropped to 2106. In 1997, an outbreak in Sao Paulo spread rapidly, infecting more than 52,000 people in Brazil alone. But by 1999, sustained vaccination brought the annual regional total back to 3209. There have now been no new locally transmitted cases since 20 September 2002.

It is essential that vaccination rates remain high, to protect against imported cases from countries with low vaccine coverage, says the PAHO.

MMR fears
 

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Measles Initiative

In February, a consortium of five leading global health organisations, including the World Health Organization and the PAHO, launched the Measles Initiative, which will initially focus on vaccinating 200 million children in Africa, with the aim of saving 1.2 million lives over five years.

Ciro de Quadros, a consultant to the PAHO, says that if Latin America can demonstrate an absence of locally acquired cases for a sustained period of at least two years, a global measles eradication programme should be launched.

But global eradication will also require a willingness of parents in developed countries to vaccinate their children against measles. Recent fears over the triple action measles, mumps and rubella (MMR) vaccine in the UK have to a drop in levels of measles protection.

Currently in the UK, just 84 per cent of children aged two years have received the MMR jab, down from 92 per cent in 1995. In London, the figure is now just 72 per cent.

Emma Young

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