The introduction of 7-valent pneumococcal conjugate vaccine (PCV7) into the U.S. childhood immunization schedule in 2000 has substantially reduced the incidence of vaccine-serotype invasive pneumococcal disease in young children and in unvaccinated older children and adults. By 2004, hospitalizations associated with pneumonia from any cause had also declined markedly among young children. Because of concerns about increases in disease caused by nonvaccine serotypes, we wanted to determine whether the reduction in pneumonia-related hospitalizations among young children had been sustained through 2009 and whether such hospitalizations in older age groups had also declined.
We estimated annual rates of hospitalization for pneumonia from any cause using the Nationwide Inpatient Sample database. The reason for hospitalization was classified as pneumonia if pneumonia was the first listed diagnosis or if it was listed after a first diagnosis of sepsis, meningitis, or empyema. Average annual rates of pneumonia-related hospitalizations from 1997 through 1999 (before the introduction of PCV7) and from 2007 through 2009 (well after its introduction) were used to estimate annual declines in hospitalizations due to pneumonia.
The annual rate of hospitalization for pneumonia among children younger than 2 years of age declined by 551.1 per 100,000 children (95% confidence interval [CI], 445.1 to 657.1), which translates to 47,000 fewer hospitalizations annually than expected on the basis of the rates before PCV7 was introduced. The rate for adults 85 years of age or older declined by 1300.8 per 100,000 (95% CI, 984.0 to 1617.6), which translates to 73,000 fewer hospitalizations annually. For the three age groups of 18 to 39 years, 65 to 74 years, and 75 to 84 years, the annual rate of hospitalization for pneumonia declined by 8.4 per 100,000 (95% CI, 0.6 to 16.2), 85.3 per 100,000 (95% CI, 7.0 to 163.6), and 359.8 per 100,000 (95% CI, 199.6 to 520.0), respectively. Overall, we estimated an age-adjusted annual reduction of 54.8 per 100,000 (95% CI, 41.0 to 68.5), or 168,000 fewer hospitalizations for pneumonia annually.
Declines in hospitalizations for childhood pneumonia were sustained during the decade after the introduction of PCV7. Substantial reductions in hospitalizations for pneumonia among adults were also observed. (Funded by the Centers for Disease Control and Prevention.)
Supported in part by grants from the Centers for Disease Control and Prevention (11-IPA1110211, to Dr. Griffin, and 12-IPA1210402, to Dr. Grijalva) and the Thrasher Research Fund (02832-9, to Dr. Grijalva).
Dr. Grijalva reports receiving consulting fees from GlaxoSmithKline and grant support through his institution from Pfizer; and Dr. Griffin, grant support through her institution from Pfizer. No other potential conflict of interest relevant to this article was reported.
Disclosure forms provided by the authors are available with the full text of this article at NEJM.org.
From the Departments of Preventive Medicine (M.R.G., C.G.G.), Medicine (M.R.G.), and Biostatistics (Y.Z.), Vanderbilt University School of Medicine, and the Mid-South Geriatric Research Education and Clinical Center, Veterans Affairs Tennessee Valley Health Care System (M.R.G., C.G.G.), Nashville; and the National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta (M.R.M., C.G.W.).
Address reprint requests to Dr. Griffin at the Department of Preventive Medicine, Suite 2600, Village at Vanderbilt, 1500 21st Ave. S., Nashville, TN 37212, or firstname.lastname@example.org.