Immunizing infants against pneumococcal pneumonia with the 7-valent pneumococcal conjugate vaccine (PCV7) not only led to a dramatic decline in hospitalizations among the very youngest patients but also was associated with a drop in pneumococcal hospitalizations among the most vulnerable unvaccinated patients, those aged 85 years and older, according to results from a study published in the July 10 issue of the New England Journal of Medicine.
Marie R. Griffin, MD, MPH, from the Department of Preventive Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, and colleagues found that annual hospitalization rates for pneumonia had fallen since the 2000 introduction of PCV7 vaccine, with an across-the-board benefit regardless of immunization status, by an age-adjusted decline rate of 54.8 hospitalizations per 100,000 individuals (95% confidence interval [CI], 41.0 - 68.5), which accounts for 168,000 fewer pneumococcal hospitalizations annually.
Using data from the Nationwide Inpatient Sample, the largest US all-payer database, with data from about 8 million annual hospitalizations, the investigators looked at the number of hospitalizations for the 3 years before the introduction of PCV13 in 2010 and compared them with the number of pneumococcal hospitalizations in the population in 1997-1999 (before PCV7 was introduced), arriving at the calculation for reduced hospitalization.
"That's very good news," Ciro de Quadros, MD, MPH, executive vice president and director of vaccine advocacy and education, Sabin Vaccine Institute, Washington, DC, told Medscape Medical News. Dr. de Quadros was not involved in the current study. "There's been a tremendous positive impact in 2 critical areas: [first,] the impact on hospitalizations, which is a marker for disease severity, and second and most important, is the herd immunity we're seeing. I think these are the 2 bottom lines." The Sabin Vaccine Institute is dedicated to reducing vaccine-preventable and tropical disease worldwide.
The study found that those aged 85 years and older saw hospitalization rates fall 22.8% (95% CI, 17.3% - 28.4%), which is the second largest percentage decrease in hospitalization rates. The authors calculate a fall in hospitalizations for pneumococcus of 1300.8 per 100,000 (95% CI, 984.0 - 1617.6), for a total estimated 73,000 fewer hospitalizations than anticipated. Infants younger than 2 years saw a 43.2% (95% CI, 34.9% - 51.6%) decrease in hospitalizations for pneumonia, the largest percentage decrease in any age group. The authors calculated 551.1 fewer hospitalizations per 100,000 children (95% CI, 445.1 - 657.1), for 47,000 fewer annual hospitalizations than baseline.
Hospitalizations for pneumonia also fell dramatically among those aged 75 to 84 years, with a decline of 359.8 per 100,000 (95% CI, 199.6 - 520.0). Hospitalizations fell at a rate of 85.3 per 100,000 among those aged 65 to 74 years (95% CI, 7.0 - 163.6) and at a rate of 8.4 per 100,000 (95% CI, 0.6 - 16.2) among those aged 18 to 39 years.
The introduction of PCV7 gave rise to concern that other pneumonia serotypes not covered by the vaccine would arise to erode the vaccine's benefit, but the authors saw no evidence of this. Before PCV7 was introduced, PCV7 vaccine serotypes caused 80% of invasive pneumococcal disease in young children and 51% of pneumococcal disease in those aged 85 years and older. After the vaccine introduction, total invasive pneumococcal cases, including both those caused by vaccine serotypes and those not included in the vaccine, fell 76% in children younger than 5 years and by 43% in children aged 5 to 17 years. Total pneumococcal cases fell 40% in those aged 18 to 49 years, 18% in those aged 50 to 64 years, and 37% in those aged 65 years and older.
One coauthor received consulting fees from Glaxo-SmithKline and Dr. Griffin and a coauthor received grant support through Vanderbilt from Pfizer. The other authors and Dr. de Quadros have disclosed no relevant financial relationships.
N Engl J Med. 2013;369:155-163.
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