A new vaccine could save hundreds of thousands of children each year from dying of pneumonia and related ailments, according to scientists reporting today in a leading medical journal.
The vaccine, tested by an international team of researchers in the West African nation of Gambia, was found to reduce overall childhood mortality by 16 percent. It had spinoff benefits as well.
"This vaccine not only prevents disease in kids who were vaccinated, it also interrupts transmission, so their parents and grandparents and anyone else they come in contact with are at reduced risk of getting it," said Orin Levine of the Johns Hopkins Bloomberg School of Public Health, who took part in the study.
The study is the first major vaccine trial in nearly 20 years to show a significant reduction in child mortality, he said. The next step, Levine said, is to find ways to make the injections affordable so they may be routinely offered in Africa, South Asia and other hard-hit regions.
A report on the vaccine trial appears in today's issue of The Lancet, a British medical journal. A second study, also published in The Lancet, found that pneumonia is the leading cause of death worldwide among children younger than 5. The disease is responsible for about 2 million, or nearly a fifth, of the 10.6 million deaths annually in that age group.
The vaccine targets a bacterium called Streptococcus pneumoniae, which is the leading cause of pneumonia among children in developing nations. Though the organism initially infects the lungs, it can also invade the bloodstream and tissues surrounding the brain and spinal cord. Pneumococcal meningitis can kill or cause severe brain damage.
"In developing countries, [pneumococcal disease] kills up to 50 percent of patients who get it, and 50 percent of survivors are permanently disabled," Levine said.
Officials with the World Health Organization said the vaccine, administered in three injections during the first year of life, could have a major impact on child survival.
"The results of this vaccine trial hold great promise for improving health and saving lives," Dr. Lee Jong-wook, director general of the WHO, said in a prepared statement.
A similar vaccine has virtually wiped out pneumococcal disease among U.S. children since it was first offered in 2000. But a separate vaccine targeting a different array of pneumococcal strains was needed for developing nations.
Dr. Robert Black, chairman of international health at Hopkins' Bloomberg School, is the lead author of the study that ranked causes of childhood deaths. He said poverty and poor nutrition are common denominators in the diseases.
"When children are undernourished, they die at a much higher rate," Black said. Poor nutrition hampers the ability of the immune system to resist infection, he said.
Other than pneumonia, other diseases found to be leading childhood killers were diarrheal diseases, accounting for 17 percent of the deaths; neonatal sepsis, 10 percent; and malaria, 8 percent.
Streptococcus pneumoniae is responsible for about half of pneumonia cases worldwide, experts said. Though the bacteria first enter the nose and throat, they are not the same ones responsible for "strep" throats.
The four-year vaccine trial was led by researchers from Hopkins and the United Kingdom Medical Research Council. Sponsors included the WHO, the U.S. Agency for International Development and the U.S. Centers for Disease Control and Prevention.
Wyeth Pharmaceuticals provided the vaccine.
About 17,000 children were selected at random to receive a vaccine against diphtheria, whooping cough, tetanus and haemophilus influenza, or a similar vaccine that also protected against pneumococcal disease.
They were then tracked to see how many thrived and how many died of pneumoccocal disease or other causes.
The trial, conducted in more than 1,000 villages that often lacked paved roads or addresses, was something of a logistical feat. To keep track of participants, researchers spray-painted numbers on the sides of thatched huts and recorded the numbers in log books along with photographs of elders who led compounds where families lived.
With funds from the Bill and Melinda Gates Foundation and other sources, the Hopkins contingent is looking for ways to make the vaccine affordable. At $50 a dose, the vaccine is far beyond the means of developing nations.
"We need suppliers willing to supply it at an affordable price," Levine said. "The international community and countries need to come together and be willing to pay for it at a price that sustains the supply."
The group is also working to raise awareness of pneumococcal disease among developing nations that don't fully realize its impact, Levine said.