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Last Updated: Thursday, 5 January 2006, 01:05 GMT
Diarrhoea vaccine tests 'hopeful'
A woman with her two children
Children in the developing world are at particular risk from the virus
Promising findings from two studies are offering the hope of a safe and effective vaccine against the most common cause of childhood diarrhoea.

Rotavirus kills about 500,000 children a year in developing countries, and accounts for a third of hospital admissions from diarrhoea worldwide.

The New England Journal of Medicine reports on tests of vaccines Rotateq and Rotarix involving 130,000 children.

The studies found them to be 98% and 85% effective respectively, it says.

Rotavirus is endemic and infections occur in almost all children by the time they are two or three.

The severity of infection ranges from no symptoms, through vomiting, fever, abdominal pain and watery diarrhoea to dehydrating gastroenteritis, which can be fatal.

In the UK, it is estimated that 1 in 38 children will be hospitalised for rotavirus gastroenteritis by the age of five, and that each year 14 children under five will die.

Most infections occur in children under two.

It is so devastating to children in the developing world because of the lack of prompt access to treatment and hospital care.

The quest for a safe and effective vaccine against the virus was thought to be over in the late 90s when a previous vaccine was developed.

But that had to be withdrawn from the market after it was associated with an uncommon, but potentially life-threatening condition called intussusception, where the bowel folds in on itself, causing an intestinal blockage.

Side effect checks

The first study - involving more than 68,000 infants aged six to 12 weeks - found a vaccine called Rotateq being developed by the pharmaceutical company Merck could safely prevent 98% of severe cases of viral diarrhoea and vomiting.

Rotateq targets five major strains of rotavirus, which account for 90% of rotavirus disease.

The trial involved infants in the US, Belgium, Costa Rica, Finland, Germany, Guatemala, Italy, Jamaica, Mexico, Sweden and Taiwan.

Half were given the vaccine and half a dummy version.

All were monitored to ensure there were no side effects, including intussusception.

There were no more side effects seen in the vaccine group than their peers.

The results of a trial of another oral vaccine called Rotarix, developed by GlaxoSmithKline, showed it was effective against the most common strain of rotavirus and able to prevent 85% of severe cases.

Over 63,000 infants were studied in 11 Latin American countries and Finland for between three months and a year.

Again, no difference was seen in complication rate between children given the vaccine and those given a dummy version.

Both studies found vaccination significantly reduced the number of children who had to be treated in hospital due to rotavirus.

Writing in the NEJM, Dr Roger Glass and Dr Umesh Parashar, of the US Centers for Disease Control, welcomed both studies as showing promising results.

"As vaccines become licensed and used in the US and Europe, we should expect to see a substantial reduction in winter hospitalisations, visits to doctors and clinics and parents' workdays lost to childhood diarrhoea," they said.

But they warned: "Both vaccines will need to demonstrate their efficacy in the difficult settings of developing countries if we are to achieve our goal of maximally decreasing global deaths from diarrhoea."

Dr David Brown, from the Health Protection Agency said: "The results of these large studies are significant because they demonstrate that these two vaccines have good efficacy against severe rotavirus disease and are not associated with intussusception."

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