The heptavalent pneumococcal conjugate vaccine (PCV7) is associated with an increase in hospitalizations for empyema, according to an article published in the January issue of Pediatrics. Empyema is linked to 3% of all pneumonia hospitalizations and up to one third of pneumococcal pneumonia hospitalizations. The United States licensed PCV7 in February 2000.
To determine whether the rise in empyema associated with PCV7 was present on a national level, researchers used figures from the Kids' Inpatient Database to estimate the number of pediatric patients hospitalized with empyema in 1997, 2000, 2003, and 2006. These estimates were figured as annual incidence rates per 100,000 children using US Census information. After comparing these rates for the time periods studied, researchers found that approximately 2898 children younger than 18 years (95% confidence interval [CI], 2532 - 3264) were hospitalized with empyema in 2006 — a calculated hospitalization rate of 3.7 per 100,000 (95% CI, 3.3 - 4.2). That demonstrates a nearly 70% increase over the 1997 rate of 2.2 per 100,000 (95% CI, 1.9 - 2.5). A 44% increase, to 5.5 per 100,000 (95% CI, 4.8 - 6.1), was seen in the rate of all pneumonia complications including empyema, pleural effusion, or bacterial pneumonia that necessitated a chest tube or decortications.