New childhood vaccine dropped hospitalizations in elderly, too

U.S. hospitalizations for pneumonia declined substantially, especially among children and the elderly, after introduction of the 7-valent pneumococcal conjugant vaccine (PCV7), according to a new study.

Researchers compared estimated annual rates of hospitalization for pneumonia in 1997-1999 and 2007-2009 using diagnoses from the Nationwide Inpatient Sample database. Hospitalizations were included if pneumonia was the first listed diagnosis or a secondary diagnosis after sepsis, meningitis or empyema. PCV7 was introduced into the U.S. childhood immunization schedule in 2000. Results were published in the July 11 New England Journal of Medicine.

Compared to 1997-1999, annual hospitalizations for pneumonia in children under 2 years in 2007-2009 dropped by 551.1 per 100,000 (95% CI, 445.1 to 657.1), which researchers extrapolated to 47,000 avoided hospitalizations annually. Patients age 85 and over saw an even greater decrease, of 1300.8 per 100,000 (95% CI, 984.0 to 1617.6) or 73,000 fewer hospitalizations annually. Reductions in hospitalizations were also seen in patients 18 to 39 years, 65 to 74 years and 75 to 84 years (8.4, 85.3 and 359.8 per 100,000 respectively). Overall, researchers calculated an annual reduction in pneumonia hospitalizations of 168,000 per year.

Previous research had shown that introduction of PCV7 rapidly reduced pneumonia hospitalizations among children, but there was concern that other serotypes would increase correspondingly to erode this progress, the study authors noted. This study shows that the success in reducing hospitalizations was maintained through 2009 and that the vaccine also had a significant effect on unvaccinated age groups, which is perhaps more remarkable than its success in young children, the authors said.

Although the results could be confounded by changes in coding practices, hospital admission thresholds and other factors, studies from other countries, which also found drops in pneumonia hospitalizations after PCV7 introduction, support a causal association. International studies have also shown that a substantial proportion of adult pneumonia cases are still attributable to the serotypes in the vaccine. It is uncertain whether adult vaccination with PCV13 (which contains the seven serotypes included in PCV7 and was recently recommended for immunocompromised adults in the U.S.) will add to the indirect benefits observed in this study and reduce adult pneumonia hospitalizations further, the authors concluded.