Protective effect of pertussis vaccine and the impact of waning protection: a systematic review and meta-analysis Open Access

Fulton, Roice (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/47429941z?locale=en
Published

Abstract

METHODS

We conducted a systematic review of published efficacy and effectiveness trials of pertussis vaccines, searching PubMed, the Cochrane Library, Web of Science, EMBASE, and the World Health Organization (WHO) Regional Databases. Study descriptors and outcome measures for qualifying articles were abstracted into standardized tables, and each study was assigned a grade for quality of evidence.

We performed a meta-analysis on acellular and whole-cell vaccine trials and observational studies to determine an overall effect size for vaccines currently on the market, and applied the Child Health Epidemiology Reference Group (CHERG) Rules for Evidence Review to estimate the effect of the vaccines on severe pertussis morbidity.

RESULTS

We identified eighteen studies for inclusion in the review. Twelve studies assessed the efficacy or effectiveness of pertussis vaccines currently on the market against the incidence of pertussis in children under six. Nine studies explored the long-term protective effect of acellular and/or whole-cell vaccine. We performed meta-analyses stratifying studies by type of vaccine and efficacy/effectiveness. These provided an overall effect size of 84% (95% confidence interval: 81-87%) for acellular vaccine efficacy studies and 94% (88-97%) for whole-cell vaccine effectiveness studies. No studies were identified that explored pertussis-specific mortality, but all studies indicated a significant reduction in incidence of pertussis in fully-vaccinated children under six. All studies exploring long-term protective effect of pertussis vaccine in children over six indicated either a progressive decrease in vaccine effectiveness (VE) or an increase in pertussis incidence or risk in the years following the final dose. The study demonstrating the highest quality of evidence showed an average annual increase of 42% in the odds of acquiring pertussis after the fifth and final dose of acellular pertussis.

CONCLUSION

Whole-cell and acellular pertussis vaccines currently on market are effective against severe pertussis morbidity. However, effectiveness wanes steadily after the administration of the final dose for acellular vaccines in particular, requiring the thoughtful implementation of vaccination schedules and programs that yield sustained protection in low-income countries.

Table of Contents

TABLE OF CONTENTS

ACKNOWLEDGEMENTS 2

STUDENT CONTRIBUTION 3

ABSTRACT 5

Background 5

Data sources & review methods 5

Results 6

Conclusion 7

INTRODUCTION 8

Description of the condition 8

Description of the intervention 9

Importance of this review 11

Objectives 14

METHODS 14

Criteria for considering studies for this review 14

Search methodology 20

Data collection and analysis 21

RESULTS 27

Description of studies 27

Effects of interventions 29

DISCUSSION 37

Summary of main results 37

Overall completeness and applicability of evidence 39

Quality of evidence 40

Risk of bias in included studies/in the review process 42

Conclusions and future directions 45

SUPPLEMENTARY DATA 47

FUNDING 47

CONFLICTS OF INTEREST 47

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