Rotavirus is the leading cause of severe diarrhoea in children

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The NEJM studies — in Malawi, Mexico and South Africa — are the first to show that the vaccines work in the world's most impoverished areas too. If included in vaccination programmes worldwide, such vaccines could save millions of children in the developing world, say the authors.

Rotavirus is the leading cause of severe diarrhoea in children in both developed and developing countries. The WHO estimates that more than half a million children die each year from the infection.

In the first study researchers vaccinated almost 5,000 infants in Malawi and South Africa with GlaxoSmithKline's Rotarix vaccine. Overall, it was 60 per cent effective at preventing cases of rotavirus diarrhoea and 30 per cent effective at preventing all kinds of diarrhoea.

The second study was carried out in Mexico, which introduced a rotavirus vaccine — again Rotarix — in 2007. Using public health data provided by the Ministry of Health, the researchers found that deaths from diarrhoea dropped after 2007, reaching a reduction of two-thirds by 2009.

Co-author of the Mexican study, Manish Patel, an epidemiologist from the US Centers for Disease Control and Prevention, told SciDev.Net that the most promising aspect of this study was that the vaccine "made a substantial impact on the ground, in the ordinary population".

In June last year the WHO Special Advisory group recommended that rotavirus vaccines be included in all national immunisation programmes.

Jocelyn Moyes, a medical officer in the Epidemiology and Surveillance Unit at South Africa's National Institute for Communicable Diseases, said that South Africa introduced the Rotarix vaccine in August 2009 but the country remains the only African nation to do so.

Developing countries rolling out the vaccine will face many challenges, said Moyes, including procuring additional infrastructure, such as refrigerators; sorting out supply chain logistics and training nurses.