Abstract
Background: The 13-valent pneumococcal conjugate vaccine (PCV13) is the only PCV licensed to protect against serotype 3 in children. However, conflicting estimates exist of PCV13’s direct and indirect protection vaccine effectiveness (VE) for serotype 3. Objective: Our study examined the of PCV13 for serotype 3 using different assumptions for PCV13 direct and indirect VE to model trends in serotype 3 invasive pneumococcal disease (IPD) and comparing these to observed data from the United Kingdom (UK). Methods: A dynamic transmission model of the spread of pneumococcal carriage and development of IPD was used to fit pre-PCV13–modeled IPD incidence with observed data. To allow for comparison across scenarios, post-PCV13–modeled IPD incidence was fit to observed data using assumptions for three different scenarios: (scenario 1) serotype 3 as a nonvaccine serotype, (scenario 2) VE against serotype 3 IPD of 63.5% based on a recent meta-analysis, and (scenario 3) a model-estimated VE against serotype 3. Results: Post-PCV13 introduction, modeled 2017 and average annual serotype 3 IPD incidence were within 20% and 59% of observed values for scenarios 2 and 3, respectively, but deviated by >100% for scenario 1. For adults aged ≥65 years, modeled 2017 IPD incidence in scenario 1 differed from observed data by 16% versus roughly 8% in scenarios 2 and 3. Conclusions: Observed data do not support a scenario of no serotype 3 VE, but rather a combination of direct protection among vaccinated children and a lower level of indirect protection among older adults. Policymakers should consider transmission dynamics when examining VE against covered serotypes.
Highlights
In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was licensed to target pneumococcal disease due to the most common circulating serotypes at the time (4, 6B, 9V, 14, 18C, 19F, and 23F)
Both were licensed based on World Health Organization (WHO) recommendations whereby approval of new PCVs was based on the demonstration of immunologic noninferiority to PCV7
These PCVs have been highly effective in reducing incidence of diseases such as invasive pneumococcal disease (IPD), pneumococcal pneumonia, and acute otitis media due to the vaccine serotypes [1]
Summary
In 2000, a 7-valent pneumococcal conjugate vaccine (PCV7) was licensed to target pneumococcal disease due to the most common circulating serotypes at the time (4, 6B, 9V, 14, 18C, 19F, and 23F). PCV10 and PCV13 targeted the same serotypes as PCV7 in addition to three (1, 5, and 7F) or six (1, 3, 5, 6A, 7F, and 19A) additional serotypes, respectively Both were licensed based on World Health Organization (WHO) recommendations whereby approval of new PCVs was based on the demonstration of immunologic noninferiority to PCV7. These PCVs have been highly effective in reducing incidence of diseases such as invasive pneumococcal disease (IPD), pneumococcal pneumonia, and acute otitis media due to the vaccine serotypes [1]. Objective: Our study examined the of PCV13 for serotype 3 using different assumptions for PCV13 direct and indirect VE to model trends in serotype 3 invasive pneumococcal disease (IPD) and comparing these to observed data from the United Kingdom (UK). Policymakers should consider transmission dynamics when examining VE against covered serotypes
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