Pneumococcal Vaccination Credited With Steady Drop in Pneumonia Hospitalizations

A decade after the 7-valent pneumococcal conjugate vaccine was introduced, it led to approximately 168,000 fewer annual hospitalizations for pneumonia.

Within the first few years after its introduction in 2000, the 7-valent pneumococcal conjugate vaccine (PCV7) was associated with a decline in the incidence of vaccine-serotype invasive pneumococcal disease in children and adults, as well as a decline in overall pneumonia-related hospitalizations in young children. The results of a new study, funded in part by the Centers for Disease Control and Prevention, indicate that over the first decade after the vaccine became available, reductions in pneumonia-related hospitalizations remained steady in young children and were also observed in elderly patients.

Previous research has found that pneumonia-related hospitalizations decreased by approximately 39% in children younger than 2 years by 2004. The new study, published in the July 11, 2013, issue of the New England Journal of Medicine¸ investigated whether these reductions in hospitalizations for pneumonia were sustained throughout the first decade of PCV7 use, despite an increase in disease caused by non-vaccine serotypes.

Using data from the Nationwide Inpatient Database, the researchers estimated annual hospitalization rates for pneumonia from any cause. Data was collected before the switch to the 13-valent pneumococcal conjugate vaccine (PCV13) in 2010. Annual rates were averaged for a period before the vaccine was introduced (1997 to 1999) and for a period after it was introduced (2007 to 2009). Hospitalization rates were also calculated by age for the 2009 sample, which included 1050 hospitals in 44 states. Hospitalizations were categorized as pneumonia-related if pneumonia was listed as the first diagnosis or if pneumonia was listed after a first diagnosis of sepsis, meningitis, or empyema.

The results indicated that the vaccine had the greatest impact on hospitalization rates for the very young and the very old. The annual rate of hospitalization for pneumonia among children younger than 2 years declined by 551.1 per 100,000 children—a 43.2% drop—leading to 47,000 fewer hospitalizations per year than would have been expected to occur based on rates before PCV7 was introduced. The hospitalization rate dipped soon after the vaccine became available and then stayed constant throughout the study period. The annual hospitalization rate for patients aged 85 and older declined by 1300.8 per 100,000—a 22.8% drop—leading to 73,000 fewer hospitalizations per year than would have been expected. Smaller but steady declines in hospitalization rate were also observed in adults aged 18 to 39, 65 to 74, and 75 to 84. Overall, the vaccine led to approximately 168,000 fewer hospitalizations for pneumonia each year.

The researchers conclude that sustained decreases in pneumonia-related hospitalizations in young children, combined with slower, but still significant decreases for adults led to a large overall reduction in hospitalizations in the decade following the introduction of PCV7. At this time, however, they are unsure whether PCV13 will have similar results in adults and children.