Rotavirus is the leading cause of diarrhoea-related deaths in most of the developing world. The WHO recommends two vaccines for all children worldwide — RV1, which targets one strain of the virus and is given in two doses, and RV5, a three-dose vaccine targeting five strains.
In 2008, RV1 was added to Bolivia's routine immunisation schedule, with doses recommended for all children at two and four months. Bolivia was the first country that receives support from the Global Alliance for Vaccines and Immunisation to use the vaccine.
Until now there has been a lack of data on whether RV1 is as effective in the real-life conditions of lower-middle income countries — particularly those with lots of children dying from rotavirus infections — as it has been in clinical trials.
The study, published in The British Medical Journal last month (19 June), analysed hospitalisations at six hospitals in Bolivia between March 2010 and June 2011. It found that RV1 prevented 69-77 per cent of rotavirus hospitalisations.
Manish Patel, lead author of the study and a researcher at the National Center for Immunization and Respiratory Diseases at the US Centers for Disease Control and Prevention (CDC), tells SciDev.Net that the results of the trial were "quite similar to the clinical trial results from lower-mortality middle- and high-income settings in the Americas".
Other studies have shown that overall the vaccine has performed better in upper-middle income countries than in lower-middle income countries.
“This vaccine provided effective protection against strains that are different from the vaccine strain.”
Patel says the reasons for this are not fully understood. It may be that malnutrition and co-infections in children in lower-income countries impair the immune response, he says.
What is known is that both rotavirus vaccines are less effective in countries with higher child death rates, making the Bolivian results even more encouraging considering the context in which the vaccine was used, write the study authors.
Patel adds: "This single-strain rotavirus vaccine provided effective protection against a broad range of strains that are different from the vaccine strain."
The study's authors write that both RV1 and RV5 should be used in low- and lower-middle income countries. They add that this type of study provides decision-makers with strong evidence to draw upon when faced with challenges — for example funding — that jeopardise vaccine programmes.
"Ongoing monitoring of impact, particularly in Asia and Africa, will be crucial for fully understanding the vaccines and identifying factors that would allow us to realise the full potential of the life-saving benefits of rotavirus vaccines [in these countries]," says Patel.
Another study published in The Journal of Infectious Diseases last month (18 June) showed that RRV-TV, a rotavirus vaccine targeting four strains, had an efficacy of around 60 per cent in Ghana. The next step is to test the vaccine in newborn babies.
Link to full paper in The British Medical Journal
Link to abstract in The Journal of Infectious Diseases
ReferencesThe British Medical Journal doi:10.1136/bmj.f3726 (2013)
The Journal of Infectious Diseases doi:10.1093/infdis/jit174 (2013)