Date of Award

January 2024

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Daniel Weinberger

Second Advisor

Sten Vermund

Abstract

Background. Streptococcus pneumoniae is an important cause of severe bacterial infections among children worldwide, and is the most common pathogenic cause of community-acquired pneumonia globally.1 There are currently multiple licensed pneumococcal conjugate vaccines that reduce both the risk of nasopharyngeal colonization (NP) and risk of developing IPD, in part by prompting an increase in serum antipolysaccharide immunoglobulin G (IgG) concentration.2 SIIL-PV (Pneumosil) is a vaccine developed by Serum Institute of India and PATH to protect against Streptococcus pneumoniae serotypes most common in LMICs, and at a lower comparative cost to its competitors.3 As this vaccine is relatively new, it is critical to understand the protection it offers compared to other pneumococcal vaccines (both licensed and in development) when administered to healthy infants.

Methods. A literature review was conducted to identify head-to-head vaccine trials with published immunogenicity data, and data were subsequently used to calculate the geometric mean ratio and inverse variance weighted averages for each vaccine comparison. Finally, the relative risk of colonization after vaccination was estimated using the natural logarithm of the geometric mean ratio, and a serotype and ethnicity-specific b1ij coefficient (representing likelihood of NP acquisition), which was identified by fitting models to NP acquisition and immunogenicity data from a large pneumococcal vaccine trial of PCV7 and PCV13, which examined vaccine effects in different ethnic populations (Bedouin & Jewish).

Results. Overall, 1164 publications were identified that contained the selected search terms, and 11 head-to-head vaccine trials selected that met the study criteria. Analyses of study data indicate Pneumosil offers similar protection against colonization when compared to PCV13 and Synflorix, for most serotypes on both 2+1 and 3+1 schedules. At the same time, PCV13 and PCV15 offer similar protection against colonization post-primary series on both vaccine schedules, and better overall protection against colonization after the booster dose. Finally, relative to PCV20, PCV13 was found to offer better vaccine protection against colonization after the booster dose on both schedules, with fewer comparative benefits post-primary series.

Conclusion. Because Pneumosil offers comparable protection against pneumococcal colonization to incumbent vaccines such as Synflorix and PCV13, I predict Pneumosil would offer similar benefits to those which were observed when comparing PCV13 to PCV15 (with PCV13 providing comparable protection against colonization post-primary series on both schedules, and better protection after the booster dose), and PCV13 to PCV20 (where PCV13 offered better protection against colonization after the booster dose on both schedules, with fewer comparative benefits post-primary series).

Comments

This is an Open Access Thesis.

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