A vaccine tested in Gambia in west Africa has proven highly effective against one of the world's deadliest childhood organisms, the pneumococcal bacterium. The international group of donors and researchers responsible for the trial says their work shows that the pneumococcal vaccine could prevent hundreds of thousands of child deaths each year if it can be used widely.
Pneumococcal bacteria kill more children in poor countries each year than any other infectious disease, including malaria and AIDS. The World Health Organization estimates the annual pneumococcal death toll at between 700,000 and one million children, mainly from the lung infection pneumonia, the brain and spinal cord disease meningitis, and blood infections.
A vaccine used in the United States since 2000 has caused an 80 percent drop in the annual number of pneumococcal cases among children under age two, the group at highest risk.
"Overall the reduction in disease in the United States has been huge." said Cynthia Whitney heads the respiratory diseases branch at the U.S. government's disease tracking agency, the Centers for Disease Control. "Our challenge now is figuring out how to prevent pneumococcal disease in developing countries, where most of the deaths in children occur."
The results of a successful four-year vaccine trial in Gambia could the lead the way. The study was supported by a coalition of international partners, including the Gambian, U.S. and British governments. Out of 17,000 babies under age one, half received three shots of the pneumococcal vaccine while the other half got inoculated for another form of bacterial meningitis.
According to results published in the journal "Lancet," those who got the pneumococcal vaccine had 77 percent fewer infections and 37 percent fewer cases of pneumonia, the most common and deadly pneumococcal disease. Moreover, they had 15 percent fewer hospital admissions and 16 percent fewer deaths.
The mortality decrease surprised the medical team that ran the trial. Co-researcher Orin Levine of the Global Alliance for Vaccines and Immunization says it was a larger drop in deaths than any other vaccine trial in nearly 20 years and shows that pneumococcal disease is much more devastating than previously believed.
"It rarely occurs that the difference in mortality between the two groups is statistically significant. The reason, frankly, that this showed up is because the burden of pneumococcal disease is so enormous and the vaccine was so effective that a trial designed to prevent pneumonia uncovered this huge burden of mortality that is preventable," he said.
The research group says the Gambian study, which occurred in a rural setting with high child mortality, makes them confident the pneumococcal vaccine will be effective elsewhere in Africa and the developing world.
The challenge, they say, is getting it to where it is needed. Dr. Levine says it can take 20 years for a vaccine to be adopted globally, partly because governments of poor countries are slow to accept them. An official at the U.S. government's Agency for International Development, Gloria Steele, cites some of the obstacles.
"The challenges in trying to make this more available include, for instance, the weak health systems in the countries that could benefit from them," he said. "Then, of course, there is the issue of corruption in the health systems in many of the countries in which we work. The result of this is that the vaccines, although available, are not accessible to many and the vaccine coverage is very low."
Ms. Steele says her U.S. government agency is seeking international partners to help fund pneumococcal vaccine distribution. Dr. Levine says the Global Alliance for Vaccines and Immunization is embarking on a campaign to inform developing nations of the new vaccine's importance. The goal, he notes, is to stimulate demand that will prompt donors to supply money and industry to produce the vaccine so every child who needs it can get it. "We have the vaccine available. We want to make sure that the good news doesn't end here," she said.