April 14, 2006

Pneumococcal vaccine offers perks to newborns

Featured Image

Katherine Poehling, M.D., M.P.H.

Pneumococcal vaccine offers perks to newborns

Even young, unvaccinated children may reap benefits when older children are vaccinated against a common bacterial infection, according to a new study by Katherine Poehling, M.D., M.P.H., and colleagues in the April 12 issue of the Journal of the American Medical Association (JAMA).

The bacterium Streptococcus pneumoniae, commonly known as pneumococcus, is a major cause of invasive infections such as of pneumonia, meningitis and bacteremia (infection in the blood) in children and adults.

Since 2000, a pneumococcal vaccine (PCV7) has been recommended for all children aged two to 23 months. Since then, rates of invasive pneumococcal disease (IPD) have substantially decreased in both children under two years and adults.

To determine whether PCV7 vaccination in the target group (ages 2 to 23 months) also offered protection to children too young to be vaccinated, Poehling and colleagues analyzed the rates of IPD among young infants before and after PCV7 was incorporated into the childhood immunization schedule.

The researchers examined pneumococcal infection data from July 1997 through June 2004 for infants aged 0 to 90 days from eight U.S. states.

They found that the average rate of IPD decreased by 39 percent, 45 percent, and 32 percent for infants aged 0 to 30 days, 31 to 60 days, and 61 to 90 days, respectively. Also, a significant decrease in the rate of IPD in black infants during this period eliminated the racial disparity in pneumococcal disease seen before PCV7 was introduced.

The findings showed that infants too young to receive the vaccination also have experienced a decrease in the rate of the disease, possibly because they were less likely to contract it from others who were vaccinated.

“These data are the first to suggest that infants too young to receive PCV7 are benefiting from the vaccination of children 2 to 23 months of age,” said Poehling, an assistant professor of Pediatrics at Vanderbilt University Medical Center.

“These results, in addition to data showing the benefit of PCV7 vaccination on adults, suggest that vaccinated children are less likely to carry the pneumococcal serotypes contained in the vaccine in their nasal passages and thus are less likely to spread it to others.”

“Continued surveillance of IPD in this and other age groups is important to determine if this trend continues or if serotypes not included in PCV7 will emerge as an important cause of IPD in neonates and young infants,” she said.