Long-Term Changes in Endemic Threshold Populations for Pertussis in England and Wales: A Spatiotemporal Analysis of Lancashire and South Wales, 1940-69

Munro, Alastair D; Smallman-Raynor, Matthew; Algar, Adam C

Abstract

Metapopulation dynamics play a critical role in driving endemic persistence and transmission of childhood infections. The endemic threshold concept, also referred to as critical community size (CCS), is a key example and is defined as the minimumpopulation size required to sustain a continuous chain of infection transmission. The concept is fundamental to the implementation of effective vaccine-based disease control programmes. Vaccination serves to increase endemic threshold population size, promoting disease fadeout and eventual elimination of infection. To date, empirical investigations of the relationship between vaccination and endemic threshold population size have tended to focus on isolated populations in island communities. Very few studies have examined endemic threshold dynamics in ‘mainland’ regional populations with complex hierarchical spatial structures and varying levels of connectivity between subpopulations. The present paper provides the first spatially explicit analysis of the temporal changes in endemic threshold populations for one vaccine-preventable childhood infection (pertussis) in two dynamic regions of England and Wales: Lancashire and South Wales. Drawing upon weekly disease records of the Registrar-General of England and Wales over a 30-year period (January 1940–December 1969) regression techniques were used to estimate the endemic threshold size for pertussis in the two study regions. Survival analyses were performed to compare disease fadeout duration and probability for both regions in the pre-vaccine and vaccine eras, respectively. Our findings reveal the introduction of mass vaccination led to a considerable increase in threshold size for both Lancashire (~387,333) and South Wales (~1,460,667). Significant growth in fadeout duration was observed in the vaccine era for pertussis non-hotspots in both regions, consistent with geographical synchronisation of epidemic activity. Regional differences in endemic threshold populations reflect significant regional variations inspatial connectivity, population dispersion and level of geographical isolation.

Citation

Munro, A. D., Smallman-Raynor, M., & Algar, A. C. (2021). Long-Term Changes in Endemic Threshold Populations for Pertussis in England and Wales: A Spatiotemporal Analysis of Lancashire and South Wales, 1940-69. Social Science and Medicine, 288, Article 113295. https://doi.org/10.1016/j.socscimed.2020.113295

• Journal Article Type: Article
• Acceptance Date: Aug 13, 2020
• Online Publication Date: Aug 22, 2020
• Publication Date: 2021-11
• Deposit Date: Aug 21, 2020
• Publicly Available Date: Aug 23, 2021
• Journal: Social Science & Medicine
• Print ISSN: 0277-9536
• Electronic ISSN: 0277-9536
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 288
• Article Number: 113295
• DOI: https://doi.org/10.1016/j.socscimed.2020.113295
• Keywords: England and Wales; Endemic threshold; disease persistence; childhood infections; geographical connectivity; pertussis
• Public URL: https://nottingham-repository.worktribe.com/output/4846264
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0277953620305141