October 1999
SAN FRANCISCO - An investigational pneumococcal vaccine appears effective in preventing pneumococcal pneumonia in children, according to data presented here at the Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC).
The seven-valent pneumococcal conjugate vaccine (Wyeth Lederle Vaccines) resulted in a 73% reduction in severe pneumonia as confirmed by an X-ray showing a large area of infection; a 33% reduction in pneumonia, as confirmed by an X-ray showing any infection; and an 11% reduction in clinical visits with a diagnosis of pneumonia.
The results of the three-year randomized, double-blinded trial were presented by the lead investigators, Henry Shinefield, MD, and Steven B. Black, MD, who are codirectors of the Kaiser Permanente Vaccine Study Center.
The vaccine contains the seven serotypes of Streptococcus pneumoniae that are most prevalent in the United States, and are also the most resistant to antibiotics.
More than 38,000 children at 23 Kaiser Permanente sites in California were involved in the study. Half the children received the pneumococcal vaccine and half received a control vaccine. Each child was given doses at 2, 4 and 6 months of age, with a fourth dose at 12-15 months.
"As children reach the age of 2, the disease risk goes down but really doesn't fall off to a small number until children reach school age," said Black, a member of the Infectious Diseases in Children editorial board. "So, given that the vaccine is safe, and fewer doses are required for older children, it makes sense to protect children up to age 5 by immunizing them to help prevent all types of pneumococcal disease, including the invasive disease as well as pneumonia and otitis media."
An updated analysis of other data collected in the trial suggest that the vaccine may also prevent invasive disease. It may also reduce physician visits for otitis media and reduce the need for tympanostomy tubes. "We have extensively evaluated the vaccine's safety and efficacy in a large population over a long time. I think parents and physicians will welcome this vaccine because it will be effective in fighting a threat to the health of young children," Shinefield said.
Pneumococcus is the leading cause of bacterial pneumonia and worldwide causes 1.2 million deaths a year, with nearly 40% of those deaths among children. S. pneumoniae also causes otitis media, sinusitis and invasive disease like bacteremia and meningitis.
"Pneumonia is a surprisingly common, yet life-threatening event in children," Black said, "and our study showed that pneumococcal bacteria accounts for more cases than we previously thought. Naturally, as physicians, we are very pleased with the efficacy this vaccine showed in reducing pneumonia in children, especially the most severe cases."
For more information:
- Black S. Efficacy of heptavalent conjugate pneumococcal vaccine (Wyeth Lederle) in 37,000 infants and children: Impact of pneumonia, otitis media, and an update on invasive diseases - results of the Northern California Kaiser Permanente efficacy trial. Session 143.G,L. Presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy. Sept. 26-29. San Francisco.
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