VACCINES: THE CASE OF MEASLES

Wednesday, 25th of May 2011

Best viewed at http://www.nature.com/news/2011/110525/full/473434a.html

 Published online 25 May 2011 | Nature 473, 434-435 (2011) | doi:10.1038/473434a

News Feature

Vaccination campaigns against measles have had dramatic results — but eradicating the disease is still a distant prospect.

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Great advances in the development and distribution of vaccines mean that some diseases can be eradicated. Measles is an important case study: efforts to stem the disease have been successful, but uneven political commitment, lack of funds and public fear threaten to undermine the progress.

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PAST: A KILLER CRUSHED

In 1980, before vaccination was widespread, there were around 4 million cases of measles and an estimated 2.6 million deaths from the disease worldwide¹. Childhood mortality targets set by the United Nations, along with accelerated control programmes, have cut the proportion of childhood deaths caused by measles from 7% in 1990 to 1% in 2008².

PRESENT: TROUBLE SPOTS

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Ideally, 95% of children need to receive two doses of a measles-containing vaccine to interrupt disease transmission. By 2009, almost 60% of countries had achieved 90% coverage with at least one dose — but some are still far below this, and some are slipping backwards.

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United States Measles was officially eliminated in 2000, but cases imported from elsewhere threaten to reestablish the virus. More cases have been registered in 2011 than in any year since 1996, leading to fears of outbreaks among unvaccinated children.

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India India is struggling to reduce deaths from measles³, mainly because of a lack of money and political will to provide two doses of vaccine to all children. There are some indications that this is changing.

Europe More than 30,000 measles cases were reported in 2010, five times more than the annual average for the past five years⁴. Many have been traced back to a major Bulgarian outbreak in 2009–10. Unfounded fears over the measles, mumps and rubella (MMR) vaccine have contributed to the resurgence.

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Africa Outbreaks have been seen in 28 countries in the past two years⁵, mainly because of a lack of funding and political commitment to follow-up vaccination campaigns, and problems with vaccine delivery. There has also been resistance among some religious groups in Zimbabwe, Botswana, Malawi and South Africa.

FUTURE: FUNDING FEARS AND UNCERTAINTY

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Because measles deaths have fallen, vaccination efforts now compete for funding with other diseases, so investment has dropped. Some countries are struggling to introduce the recommended second dose of measles-containing vaccine, let alone new vaccines — for invasive pneumococcal disease and rotavirus, for example — that could save many more lives.

Assuming no catch-up immunizations in troubled countries, public-health officials predict a worst-case scenario in which the death toll could exceed 500,000 by 2013¹.

In a 'status-quo' scenario, modest increases in first-dose vaccine coverage are complemented by catch-up immunizations at about 2008 levels — but this still falls short of global eradication.