The Lancet has today published online new research from a team led by the UK Medical Research Council's Richard Adegbola showing that routinely vaccinating infants against H. influenzae type b (Hib) - a bacterium that causes deadly diseases including pneumonia and meningitis - has virtually eliminated Hib meningitis in The Gambia.
The Gambian study shows that the vaccine is highly effective (94% efficacy with two doses) and that, even with moderate coverage and sub-optimal conditions, Hib vaccination can benefit all children because herd immunity is significant.
"Hundreds of thousands of young children are dying of Hib disease because of a lack of national Hib immunization programs," said Dr. Patrick Zuber of the Vaccines and Biologicals division of the World Health Organization (WHO). "This study proves that routinely immunizing children with Hib conjugate vaccine in developing countries is practical and will save lives - helping in the efforts to achieve a two-thirds reduction in the under-five mortality rate, a Millennium Development Goal."
"What makes this even more remarkable is that the virtual eradication of Hib disease has been achieved despite less than optimal circumstances," said lead study author Dr. Adegbola of the MRC. "There were interruptions in vaccine supply, less than 70% of children received the complete schedule of immunizations, and vaccine doses were often received late. This makes the Gambian findings particularly relevant to the real-life situation in other developing countries, especially in sub-Saharan Africa."
The study also showed that Hib carriage has also been virtually eliminated in The Gambia - in both vaccinated and unvaccinated children. Before vaccination 12% of children between one and two years old carried the infectious bacteria, now the rate is less than half of one percent and difficult to detect. The negligible carriage rates contribute to the herd immunity effect - unvaccinated children are protected because of reduced likelihood of transmission. This means that routine Hib conjugate vaccination is a highly effective way of preventing death and severe disability related to Hib disease in young children.
Prof. Orin Levine, Executive Director of GAVI's pneumococcal vaccine project, PneumoADIP said, "To nearly eradicate Hib meningitis from this area of Africa speaks volumes about the Gambia's program and the impact Hib vaccine will have on global health."