乌鸦传媒

Community-acquired pneumonia (CAP) is a leading cause of hospitalization and death, with the greatest burden on young children and older adults. Worldwide, the pathogens driving the lion鈥檚 share of acute bacterial pneumonia are Streptococcus pneumoniae and Haemophilus influenzae. In the U.S., recent epidemiologic surveillance indicates that human rhinovirus, influenza virus, and S pneumoniae are the most common drivers.¹

Globally, incidence of CAP ranges from 1.5 to 14.0 cases per 1000 person-years, varying by geography, season, and local demographics. Annual incidence in the U.S. stands at 24.8 cases per 10,000 adults, with rates increasing with age.¹ In terms of related hospitalizations, based on a meta-analysis of 52 studies, Shi and colleagues estimated that 6.8 million episodes of clinical pneumonia resulted in hospital admissions of adults ages 65 and older worldwide in 2015, including some 1.1 million in-hospital deaths.²

To control these rates and further reduce them, the U.S. Food and Drug Administration (FDA) licensed a first-in-class, 7-valent pneumococcal conjugate vaccine (PCV7) in 2000, when the U.S. began routine use of PCV7 in children. A decade later in 2010, the FDA approved the use of PCV13 in kids, extending it to adults 50 years or older in 2011.³ 

An analysis of the vaccine鈥檚 effectiveness

While abundant data support the current indications for PCV13, the association of its use with

pneumonia hospitalization in older adults is not well characterized, especially among those with underlying medical conditions. To address this knowledge gap, Kobayashi and colleagues analyzed claims data from more than 24 million Medicare beneficiaries 65 years or older, comparing outcomes among seniors who had received PCV13 vaccination at least 14 days before a pneumonia hospitalization to those who had not.⁴ The study estimated the adjusted incidence rate ratio (IRR) and number of pneumonia hospitalizations averted through PCV13, using the adjusted IRR for the association of PCV13 vaccination with pneumonia hospitalization to estimate vaccine effectiveness. 

By the end of the study, roughly 1 in 5 participants (20.5%) had received PCV13 (and no other pneumococcal vaccine), and the remainder (79.5%) had not received any pneumococcal vaccine. A majority of participants were younger than 75 years old, White, and had 1 or more immunocompromising or chronic medical condition. The study estimated the vaccine effectiveness for PCV13 at 6.7% (95% confidence interval [CI] 5.9% to 7.5%) for pneumonia, 4.7% (95% CI 3.9% to 5.6%) for non-healthcare-associated pneumonia, and 5.8% (95% CI 2.6% to 8.9%) for lobar pneumonia.

From September 2014 through December 2017, the study estimated that the use of PCV13 averted 35,127 hospitalizations for pneumonia (95% CI 33,011 to 37,270), 24,643 for non-healthcare-associated pneumonia (95% CI 22,761 to 26,552), and 1294 for lobar pneumonia (95% CI 797 to 1819).

Even older and sicker patients show a benefit

Kobayashi and colleagues note that vaccine effectiveness was lower among older participants compared to young ones, as well as in adults with underlying medical conditions versus those who did not have such conditions.⁴ In addition, the overall estimate of vaccine effectiveness (6.7%) was similar to the finding in the Community-Acquired Pneumonia Immunization Trial in Adults (CAPITA), which reported PCV13 efficacy of 5.1% (95% CI 鈭�5.1% to 14.2%) against a first episode of CAP from any cause.⁵

The authors of the current study also noted that previous observational studies using administrative data to estimate the effectiveness of PCV13 included fewer adults with immunocompromising conditions than the current study, in which some 40% of participants had immunocompromising conditions. Kobayashi and colleagues point to an estimate from the National Health Interview Survey that more than 63% of adults 65 and older have multiple underlying chronic conditions,⁶ suggesting that the current study population鈥攚hich included about half of adults ages 65 or older from all 50 states and Washington, D.C.鈥攊s likely to be more representative of older adults with underlying conditions than the cohorts analyzed in previous studies.

The study concluded that vaccination with PCV13 reduced pneumonia hospitalizations among adults 65 or older, including many with underlying medical conditions.

鈥淎s adults grow older, a larger proportion have underlying medical conditions that increase their risk of pneumococcal disease,鈥� says Miwako Kobayashi, MD, MPH, a medical epidemiologist at the Centers for Disease Control and Prevention in Atlanta, and lead author of the study. 鈥淯se of new PCVs that were recently approved for U.S. adults is important because, as our study shows, they鈥檙e likely to be protective against pneumonia hospitalizations, even for adults with underlying conditions.鈥�

Published: January 10, 2024