Investigators led by Samir Shah, MD, conducted the first national study to comprehensively examine rates of pneumonia-related complications before and after a vaccine designed to prevent infection with the leading bacterial cause of pneumonia was introduced. The vaccine, known as PCV7, was introduced in the United States 10 years ago. Using data collected from 1997 to 2006, the investigators found that the vaccine appears to reduce hospitalizations for pneumonia by 22 percent in the vaccine's target range, children less than a year old. Conversely, the rate of hospitalization for pneumonia increased in older children, by 22 percent for children ages 6 to 12 years and by more than 40 percent for children older than 13.
The study team also found that the rate of systemic complications such as sepsis and respiratory failure decreased by 9 percent overall and about 35 percent for infants less than 1 year of age. In contrast, rates of hospitalization for lung complications such as empyema increased by more than 70 percent for children between 1 and 18 years of age. The overall decrease in systemic complication rates could be attributed to the decrease in rates for infants, who are the primary recipients of the vaccine. However, the reasons for increased rates of lung complications are unclear.
The vaccine may also disproportionately benefit black children according the study, which was published in Pediatrics. Previous studies have shown that black children have a higher frequency of pneumococcal infections, including pneumonia. The current study found that while the rates of pneumonia were higher for black children compared to white children in all years of the study, the difference narrowed from a ratio of 1.98 in 1997 to a ratio of 1.59 in 2006.
Funding support for the study came from the Academic Pediatric Association Young Investigator Award, the National Institute of Allergy and Infectious Diseases, and the Robert Wood Johnson Foundation.