Effectiveness of Hib vaccine introduction into routine childhood immunization in Kenya

The Journal of the American Medical Association (JAMA) today published research showing that, three years after introduction, routine vaccination of infants in Kenya against H. influenzae Type b (Hib) significantly reduced invasive Hib disease rates by 88%.

The paper, entitled: Effectiveness of Haemophilus influenzae Type b (Hib) Conjugate Vaccine Introduction into Routine Childhood Immunization in Kenya, was authored by a team led by Oxford University's Dr. Anthony Scott. According to the study, Hib vaccine:

• Reduced laboratory-confirmed invasive Hib disease by 88% below baseline
• Prevented an estimated 3,370 hospitalizations in Kenya in 2005

The Hib bacterium is a deadly cause of invasive disease such as meningitis and bloodstream infections, and an important cause of severe pneumonia in children under 5 years of age. Most deaths occur in the developing world, and Africa accounts for more deaths due to Hib than any other continent.

Commenting on the study, Karen Cowgill, lead author and, at the time of the study, Epidemic Intelligence Service officer at the Centers for Disease Control and Prevention in the US, said: "These results demonstrate the effectiveness of the Hib vaccine in reducing severe childhood illness and associated deaths in Kenya, and lead us to conclude that many more deaths could be averted in Africa if more countries added the vaccine to their routine immunization programs."

This is the first published study in East Africa to document the significant benefit of routine Hib vaccination in protecting young children against the devastating effects of a leading cause of childhood meningitis and pneumonia in the developing world. The findings build on a considerable body of growing evidence from Africa and around the world: similar results have been observed in The Gambia, Chile, the US, and UK. The findings contained within the study can reasonably be expected to apply to other African settings too.

Recently, a number of developing countries have begun routinely vaccinating children against Hib disease. Yet despite the overwhelming evidence and support in favour of these vaccines, less than 40% of African countries have adopted the Hib vaccine. One major obstacle has been the lack of available data on Hib disease burden and vaccine effectiveness.

"It is vital to support public health interventions such as the introduction of Hib vaccine with hard evidence", said Dr. Sharif, Deputy Director of Medical Services within the Ministry of Health, Kenya. "The strength of our surveillance systems will also assist us with the evaluation of new vaccines to prevent other leading child killers such as pneumococcus and rotavirus", he added.

Surveillance to monitor the impact of health and vaccination programs is essential. "Building the evidence base for the introduction of new and underused life-saving vaccines is a critical step in understanding what interventions countries need to save more lives faster", said Julian Lob-Levyt, Executive Secretary, GAVI Alliance. "If you can measure the impact a disease is having on your country, it is easier to build the case for preventing it", he added.

Worldwide, Hib disease is estimated to cause 3 million episodes of serious disease each year, leading to 400,000 childhood deaths. Where Hib vaccine has been routinely used, disease has been virtually eliminated. If countries, donors and industry can be mobilized to introduce Hib vaccine, parents, children and healthcare providers in Africa could also see death and suffering due to Hib become a concern of the past.

The GAVI Alliance, together with partners and stakeholders in Kenya and other developing countries, is working collaboratively to provide funding for vaccine programs and to implement programs to improve health systems and strengthen surveillance networks.

This study further supports the WHO's Strategic advisory Group of Experts (SAGE) and Africa's Task Force on Immunization's recommendations for global implementation of Hib vaccine and suggests that routine use could help reach the Millennium Development Goal of reducing child mortality by two-thirds by 2015.