Evaluating the impact of pneumococcal conjugate vaccines on childhood disease burden and antibiotic use: evidence from the United Kingdom and Sub-Saharan Africa

Abstract

Introduction:
Evidence on long-term, real-world effectiveness of pneumococcal conjugate vaccines (PCVs) remains limited. This thesis evaluated the impact of PCVs on invasive pneumococcal disease (IPD) burden and antibiotic use in the United Kingdom (UK) and across multiple countries in sub-Saharan Africa (SSA).

Methods:
A systematic review summarised existing research on PCV13 effectiveness in reducing childhood IPD incidence and all-cause mortality. Three population-based studies were then conducted: (i) an interrupted time series analysis using IQVIA Medical Research Data (IMRD) from 2008–2019 to assess the impact of PCV13 on IPD incidence among UK children aged 0–18 years; (ii) an evaluation of oral antibiotic prescribing for IPD treatment in UK primary care; and (iii) an analysis of Demographic and Health Survey (DHS) data from 18 SSA countries to examine PCV coverage, antibiotic use for acute respiratory infections (ARI), and under-five mortality.

Results:
The systematic review identified 11 studies demonstrating thta PCV13 introduction resulted in substantial declines in pneumonia incidence in children under two years, and childhood mortality reductions of 28.6–47.0% in infants under one year. In the UK, PCV13 introduction in 2010 was associated with an immediate 22% reduction in IPD incidence and a 33% decline in antibiotic prescribing, notably in children under two. Access-group antibiotics accounted for over 80% of prescriptions, with amoxicillin representing more than 70%. In SSA, PCV coverage varied widely, with dropout rates ranging from 0.8% to 35.3%. Maternal education strongly predicted full vaccination. Each 1% increase in national PCV coverage was associated with one fewer under-five death per 1,000 live births.

Discussion and Conclusion:
PCV13 substantially reduced IPD burden and antibiotic prescribing in the UK. In SSA, inequities in vaccine coverage and healthcare access limit vaccine impact. These findings support sustained expansion of PCV programmes and ongoing monitoring of vaccine effectiveness and antibiotic use globally.

Thesis is embargoed until 31 July 2028.

Date of Award	Jul 2026
Original language	English
Awarding Institution	Queen's University Belfast
Supervisor	Carmel Hughes (Supervisor) & Yingfen Hsia (Supervisor)