Evaluating pertussis vaccine effectiveness in Manitoba using administrative and public health surveillance data
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Date
2022-03-28
Authors
Wilkinson, Krista
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Abstract
Objective: Pertussis persists in Manitoba despite a long-standing universal vaccine program; however, little is known provincially about the impact of this program on disease rates or about the effectiveness of the different pertussis vaccines used over time. Estimates of provincial pertussis vaccine coverage are lower than the national herd immunity target of 95%, but it is unclear whether periodic increases in cases are driven by an under-vaccinated cohort or if resurgences are due to low pertussis vaccine effectiveness or waning vaccine protection. This study aims to address these gaps in knowledge.
Methods: We linked several administrative datasets housed at the Manitoba Centre for Health Policy to public health surveillance data to identify laboratory-confirmed cases of pertussis between 1992 and 2017. We used age-period-cohort models to investigate population-level trends in pertussis incidence over the study period and conducted a nested case-control study to measure whole-cell and acellular pertussis vaccine effectiveness and duration of protection.
Results: The whole-cell pertussis vaccine used in Manitoba from 1981 to 1996 had low vaccine effectiveness and contributed to a large outbreak of pertussis in the mid-1990s. The acellular pertussis vaccine in use from 1997 to the present provided high early protection, which appeared to wane over time. Most hospitalizations were in children under the age of one across the study period.
Conclusion: Changes in the pertussis vaccine program contributed to outbreaks of disease many years later, highlighting the importance of ongoing disease surveillance and vaccine effectiveness estimation. Severe outcomes were almost exclusively observed in young children, making this cohort an appropriate target for future research and interventions.
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Keywords
Bordetella pertussis, Pertussis, Whooping cough, Vaccine effectiveness, Age-period-cohort analysis, Systematic review and meta-analysis