For the first time ever, studies in Mexico and Africa, published today
in the New England Journal of Medicine, demonstrate a reduction
in diarrheal disease deaths following rotavirus vaccine introduction in
Mexico and vaccine efficacy among impoverished populations in Malawi and
South Africa. Both studies underscore the importance of vaccination in
achieving significant reduction of severe rotavirus infections among
children in the developing world, where disease impact is greatest.
Worldwide, rotavirus is the leading cause of severe diarrhea, which
takes the lives of more than 500,000 children under 5 every year – with
almost half of these deaths occurring in Africa – and causes the
hospitalization of millions more.
“Diarrhea is rarely a life-threatening problem in rich countries, but in
the developing world it is a leading cause of death in children”
The findings from these studies informed the World Health Organization’s
(WHO) recent recommendation that rotavirus vaccines be included in every
nation’s immunization program. The recommendation is important for
Africa which is hit particularly hard by the disease and places
rotavirus vaccines among a comprehensive set of other interventions key
to stopping diarrheal disease deaths, including access to clean water,
proper sanitation and oral rehydration therapies (ORT), breastfeeding,
and vitamin A and zinc supplementation.
In an editorial accompanying the studies’ results, Mathuram Santosham,
Professor of International Health and Pediatrics at Johns Hopkins
University, Baltimore, welcomed these studies for supporting the use of
rotavirus vaccines in the poorest countries of the world. “We now have
another powerful weapon to add to our armamentarium to combat diarrheal
deaths – rotavirus vaccines,” wrote Santosham. “Rotavirus vaccine should
be introduced immediately in high mortality areas and it should be used
as a trigger to energize diarrhea control programs and improve coverage
for all the proven interventions for diarrhea.”
In Mexico, which in 2006 was among the first countries in the world to
introduce rotavirus vaccine, diarrheal disease death rates dropped
during the 2009 rotavirus season by more than 65 percent among children
age two and under. This demonstrates real-world impact that is crucial
as other countries consider rotavirus vaccine introduction. The Mexico
study examined the impact of vaccination on diarrheal deaths in Mexican
children between 2008 and 2009 following a phased introduction of the
orally administered RotarixTM, manufactured by
GlaxoSmithKline Biologicals (GSK).
“Mexico had previously instituted interventions, including improved
sanitation, use of oral rehydration, breastfeeding, and vitamin A
supplementation, but diarrhea-related deaths during the December-to-May
rotavirus season still remained high,” said Manish Patel, Medical
Epidemiologist, Division of Viral Diseases, National Center for
Immunizations and Respiratory Diseases, US Centers for Disease Control
and Prevention, and co-author of the Mexico study, Effect of
Rotavirus Vaccination on Death from Childhood Diarrhea in Mexico.
“The reduction in mortality following vaccine introduction points to the
importance of immunization against rotavirus as a primary prevention
tool in controlling diarrhea not just in Mexico but around the world.”
Other findings from Mexico include:
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Among infants younger than 11 months, the target age for vaccination,
diarrhea deaths fell by more than 40 percent; and
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Among children between the ages of one and two, diarrhea deaths fell
almost 30 percent, even though only 10-15 percent of this population
was eligible for vaccination. This result indicates that vaccination
of susceptible young infants may also protect unimmunized children who
live in the same community by reducing the exposure of rotavirus to
children.
In South Africa and Malawi, the results of a clinical trial showed that
the vaccine significantly reduced severe rotavirus disease – by 61.2
percent – in African infants during the first year of life. The
African clinical trial specifically focused on the vaccine’s performance
among infants in high mortality, low-income settings. More than 4,900
infants were enrolled in a clinical trial examining the efficacy of the
RotarixTM vaccine.