Pneumonia Vaccine Reduces US Hospitalizations

A new study found that annual hospitalization rates for pneumonia had fallen since the 2000 introduction of the 7-valent pneumococcal conjugate vaccine (PCV7), regardless of immunization status, by an age-adjusted reduction of 54.8 per 100,000 (95% confidence interval [CI], 41.0-68.5), which accounts for the prevention of 168,000 hospitalizations for the disease annually. Specifically, the PCV7 vaccine has led to a dramatic decline in hospitalizations among children <2 years of age. Pneumococcal hospitalizations also declined in patients ≥85 years of age [N Engl J Med. 2013;369(2):155-163].

Before the introduction of PCV7, vaccine serotypes caused 80% of invasive pneumococcal disease in young children and 51% of pneumococcal disease in those ≥85 years of age. After the vaccine introduction, invasive pneumococcal disease caused by vaccine serotypes was nearly eliminated in children <5 years of age and fell by >85% in all unvaccinated age groups. Total cases of invasive pneumococcal disease including those caused by vaccine serotypes and those not included in the vaccine, declined by 76% among children <5 years of age and by 43% in children 5 to 17 years of age. Total pneumococcal cases fell by 40% in those 18 to 49 years of age, 18% in those 50 to 64 years of age, and 37% in those ≥65 years of age.

To determine whether the early observed reductions in hospitalizations for pneumonia were sustained throughout the first 10 years of PCV7 use, the researchers conducted a comprehensive assessment of US hospitalizations for pneumonia after the introduction of PCV7 and before the switch to the 13-valent pneumococcal conjugate vaccine in 2010.

Using data from the Nationwide Inpatient Sample, the largest all-payer US inpatient care database, with data from about 8 million annual hospitalizations, the researchers looked at average annual rates of pneumonia-related hospitalizations from 1997 to 1999 (before the introduction of PCV7) and from 2007 to 2009 (after its introduction) to estimate annual declines in hospitalizations due to pneumonia. For data to qualify for study inclusion, the patient had to have a first-listed discharge diagnosis of pneumonia or a first-listed discharge diagnosis of meningitis, septicemia, or empyema in addition to a diagnosis of pneumonia in another diagnostic field.

From 1997 to 2009, there were 17,892,085 hospitalizations for pneumonia, representing 4.1% of all US hospitalizations. Pneumonia was the first-listed diagnosis for 90% of these hospitalizations, with sepsis as the first-listed diagnosis for 9% and meningitis and empyema for <1% each. The results showed that the annual rate of hospitalization for pneumonia among children <2 years of age decreased by 43.2% (95% CI, 34.9-51.6). The researchers calculated 551.1 fewer hospitalizations per 100,000 children (95% CI, 445.1-657.1), for 47,000 fewer hospitalizations than baseline.

Substantial reductions in hospitalizations for pneumonia among the elderly were also observed. The decline in hospitalizations for patients ≥85 years of age was 22.8% (95% CI, 17.3-28.4). The investigators calculated a decline in hospitalizations for pneumonia of 1300.8 per 100,000 adults (95% CI, 984.0-1617.6), which translated to 73,000 fewer hospitalizations than anticipated. For the 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, 0.6-16.2), 85.3 per 100,000 (95% CI, 7.0-163.6), and 359.8 per 100,000 (95% CI, 199.6-520.0), respectively.

In summary, the researchers said, “The reduction initially observed in hospitalizations for childhood pneumonia was sustained in the decade after 2000, when PCV7 was introduced. More modest relative declines in hospitalizations for pneumonia among older adults emerged more slowly and resulted in absolute overall reductions in hospitalizations for pneumonia.”