In a four-year study, a team led by the UK Medical Research Council's Felicity Cutts vaccinated and followed over 17,000 young children in The Gambia to study whether a vaccine that has been shown to prevent pneumococcal disease in urban South Africa would also work in the challenging environment of rural Africa. The results, to be published in the March 26 issue of The Lancet, show that the vaccine reduced childhood mortality by 16 percent in children who received the pneumococcal conjugate vaccine. This study is the first major randomized, controlled vaccine clinical trial in nearly twenty years to show a statistically significant reduction in overall child mortality.
"The results of this vaccine trial hold great promise for improving health and saving lives in resource-poor populations," said Dr. Lee Jong-wook, the director general of the World Health Organization (WHO). "The international community's task now is to continue to work together productively to make the pneumococcal conjugate vaccine widely available to children in Africa, as lives are lost every minute to pneumococcal disease. Immunizing children with pneumococcal conjugate vaccine in developing countries will be a critical intervention towards achieving a two-thirds reduction in the under-five
mortality rate, a Millennium Development Goal."
Streptococcus pneumoniae, or pneumococcus, is the bacterium that causes
pneumococcal disease. When they invade the lungs, these bacteria cause the
most common kind of bacterial pneumonia and can then invade the bloodstream
(bacteremia) or the tissues and fluids surrounding the brain and spinal cord
(meningitis). According to WHO, pneumococcal pneumonia and meningitis are
responsible for about 1.6 million deaths each year, even more than malaria.
And more than 90 percent of pneumococcal pneumonia deaths in children occur in
Previous studies had shown that this vaccine was effective in reducing the
number of pneumococcal infections in children in urban South Africa. But many
of the children suffering from pneumococcal disease in Africa live in rural
areas with high infant mortality rates, significant rates of malaria
transmission and very limited access to healthcare. The Gambia is
representative of these areas, and the results of the study suggest that the
deaths caused by pneumococcal infections in rural Africa are preventable. "The
trial results are highly positive and promising, and most importantly, they
demonstrate that pneumococcal vaccination can prevent these serious infections
even in a rural African setting," said Cutts.
Sponsors of and participants in this successful trial included the
National Institute of Allergy and Infectious Diseases (NIAID), part of the
National Institutes of Health (NIH); WHO; PATH's Children's Vaccine Program
(CVP); the U.S. Agency for International Development (USAID); Johns Hopkins
Bloomberg School of Public Health and the Centers for Disease Control and
Prevention (CDC). Wyeth Pharmaceuticals provided the trial vaccine.
Summary of trial results
In this trial:
* This vaccine significantly reduced the need for hospitalization:
children receiving the pneumococcal vaccine had 15 percent fewer
hospital admissions than those who did not.
* The nine-valent pneumococcal conjugate vaccine was 77 percent effective
in preventing pneumococcal infections caused by the vaccine serotypes.
* As a result, there were 37 percent fewer cases of pneumonia in the
children who received the vaccine compared with children who received
the control vaccine.
Working with the Global Alliance for Vaccines and Immunization (GAVI),
Wyeth Pharmaceuticals has offered to provide the pneumococcal conjugate
vaccine Prevnar to The Gambia for introduction into their national
immunization program. Wyeth is also working with GAVI's PneumoADIP and other
public health partners to facilitate access to Prevnar and future pneumococcal
conjugate vaccines with expanded serotype coverage to children in developing
The Gambia Vaccine Trial was a randomized, double-blind, placebo-
controlled trial -- the most scientifically rigorous design for a clinical
trial -- of the efficacy of nine-valent pneumococcal conjugate vaccine against
pneumonia, meningitis, and sepsis. The study was carried out in Upper and
Central River divisions of The Gambia between August 2000 and April 2004. All
17,437 infants enrolled in the trial received DTP (diphtheria, tetanus, and
pertussis) and Hib vaccines. Children had follow-up visits for two years, on
Pneumococcal disease is an infection caused by Streptococcus pneumoniae.
When these bacteria invade the lungs, they cause the most common kind of
bacterial pneumonia and can then invade the bloodstream (bacteremia) and/or
the tissues and fluids surrounding the brain and spinal cord (meningitis).
According to WHO, pneumococcal pneumonia and meningitis are responsible for
700,000 to 1 million child deaths each year and more than 90 percent of
pneumococcal pneumonia deaths in children occur in developing countries.
Source: Johns Hopkins School of Public Health