The Associated Press
 

"The vaccine is working. It is not only preventing diseases in high-risk children but also in their families," said Dr. Cynthia Whitney, who led the study for the Centers for Disease Control and Prevention.

How many infants have been immunized isn't known yet, but the vaccine has been widely adopted.

The findings appear in Thursday's New England Journal of Medicine, along with a three-year study of an older pneumonia vaccine recommended for everyone over 65. In that study of 47,365 people, the vaccine cut the risk of serious blood infections almost in half, but offered no protection against pneumonia, reflecting some previous research in the elderly.

"There's a benefit of the vaccine. It's just the benefit doesn't extend to prevention of pneumonia from what we can tell," said Dr. Lisa A. Jackson, who led the CDC-funded research at the Group Health Cooperative, an HMO based in Seattle.

Pneumococcus bacteria is carried in the nose and throat of healthy people, and is spread from person to person. The very young and the elderly are most vulnerable, as well as people with medical conditions that weaken their immune system and their ability to fight the bug.

Until 2000, pneumococcal infections resulted in up to 135,000 annual hospitalizations for pneumonia and 60,000 cases of blood infections, including 3,300 cases of meningitis, according to the CDC.

Those numbers are changing because of the new infant vaccine. The CDC study examined the vaccine's impact by tracking the more serious pneumococcal infections blood poisonings and meningitis in seven areas of the country covering 16 million people.

"It's real life. It's not a controlled study," said Whitney. "Given the price of the vaccine, I think it's really important that we figure out what's going on with this. Are we getting our money's worth?" Each of the four doses costs $61, according to the vaccine maker Wyeth.

From 1998 to 2001, the findings show, the rate of blood infections and meningitis dropped by 69 percent in children under 2 from 188 cases to 59 cases per 100,000. The rate fell 44 percent for 2-year-olds but there was no change for older children.

There was evidence that less bacteria was passed from children to adults. The disease rate dropped as much as 32 percent in adults 20 to 39.

The research also indicates that the infant vaccine can prevent infections by drug-resistant strains of bacteria. In 2001, 35 percent fewer infections were caused by strains resistant to penicillin.

"These are very important findings and if they can be confirmed more broadly and more directly ... that's really powerful stuff," said Dr. Greg Poland, director of the Mayo Clinic Vaccine Research Group, who was not involved in the studies.

He said doctors need to explain to elderly patients that, despite its name, the vaccine used in adults might not protect them against pneumonia but does prevent more lethal complications.

"That alone is enough," he said.

Jackson said a different vaccine is probably needed for the elderly, and one possibility is the infant's vaccine. It protects against seven types of pneumococcal bacteria but works differently than the older vaccine, which is designed to guard against 23 types.

The medical director of adult vaccines for Merck & Co., which makes the Pneumovax 23 vaccine, said it targets the most common but not all the strains that cause pneumonia. Nor does it guard against other causes of pneumonia which were included in the study, said Dr. Joan Benson. The vaccine costs about $16.

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