Study: Serotype 3 Remains Prevalent Among Older Adults With Community-Acquired Pneumonia


Individuals with PCV20-serotype disease were generally younger compared to those who had PCV13 serotype community-acquired pneumonia.

Even with robust infant vaccine programs against pneumococcal disease, older adults remained highly affected by pneumococcal conjugate vaccine 13 (PCV13)-serotype pneumonia, specifically with serotype 3, according to results of a study published in The Lancet Regional Health. In the study, investigators aimed to evaluate the risk factors associated with community-acquired pneumonia (CAP) in relation to vaccine serotypes to help contribute to vaccine policy.

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In the cohort study, investigators included adults who were admitted to 4 hospital universities across 3 sites in the United Kingdom, including 2 hospitals in Nottingham and 1 each in Liverpool and Edinburgh. Individuals were admitted to the hospital between April 2018 and March 2020 for CAP. Patients were eligible if they were aged 16 years and older who had 1 or more symptoms in the lower respiratory tract infection, such as cough, increasing dyspnea, and/or fever. Further, they had to have acute abnormalities showing infections in a chest radiograph taken within 48 hours of admission and were subsequently treated for CAP, according to the study investigators.

A total of 1921 patients hospitalize for CAP were included in the study, with approximately 7.8% admitted to critical care. Individuals had a median age of 70 years and were approximately 53.6% male. For pneumonia severity, approximately 51.2% had low CURB65 scores, 30.2% had moderate, and 18.6% had high, according to the study authors. Investigators also confirmed vaccination status in approximately 56.1% of patients. The median time since pneumococcal polysaccharide vaccine 23 was 10.9 years.

For individuals with CAP, 19.1% had multiple serotypes, with a single PCV13 serotype identified in 31% of patients with CAP. Serotype 3 was found in approximately 70.4% of individuals, followed by 16.9% for serotype 19A. Additionally, a single PCV15 serotype was found in 35% of individuals, with additional PCV15 serotypes, 22F and 33F, being detected in 4% of patients.

3 Key Takeaways

  1. The study reveals that older adults, even with robust infant vaccine programs targeting pneumococcal infections, remain significantly affected by pneumococcal conjugate vaccine 13 (PCV13)-serotype pneumonia.
  2. Serotype 3 is identified as the most prevalent PCV13 serotype in individuals with CAP, comprising approximately 70.4% of cases.
  3. Older individuals are more likely to be affected, and males exhibit a higher association with PCV13 serotypes compared to non-PCV13 serotypes.

Furthermore, there was a single PVC20 serotype in 55.6% of individuals with CAP, with the most common serotype in PCV, but not PCV13, being serotype 8 in 64.1% of patients. Approximately 6.8% of patients with CAP had a unique PPV23 serotype, with 49.1% being 9N, followed by PPV20 in 26.4%, and PPV17F in 22.6%, according to the study investigators. Of the 587 patients available for the analysis, approximately 43.8% had PCV13 serotype disease and 56.2% had non-PCV13 serotype. Patients with PCV13 serotypes were generally older, according to the study investigators.

Further, compared to those with non-PCV13 CAP, those who had PCV13 serotypes were more likely to die within 30 days. Males were also independently associated with PCV13 serotypes compared to non-PCV13 serotypes. Investigators found that the age of those with serotypes 22F and 33F did not differ from those with PCV13-serotype CAP. For PCV15, only cerebrovascular disease was an independent risk factor for CAP with serotypes 22F and 33F, according to the study authors.

For PCV20, patients were generally younger compared to those who had PCV13 serotype CAP. Further, the odds were lower in males and those who previously had the PPV23 vaccines. Patients with PCV20-nonPCV13 serotype CAP also had lower odds of readmission within 30 days compared to PCV13, according to the results of the study.


Lansbury L, Lawrence H, McKeever TM, French N, et al. Pneumococcal serotypes and risk factors in adult community-acquired pneumonia 2018-20; a multicentre UK cohort study. Lancet Reg Health Eur. 2023;37:100812. doi:10.1016/j.lanepe.2023.100812

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