The Impact of Public Health Interventions on Delaying and Mitigating against Replacement by SARS-CoV-2 Variants of Concern

17 Pages Posted: 8 Feb 2021

See all articles by Jianhong Wu

Jianhong Wu

York University - Laboratory for Industrial and Applied Mathematics

Francesca Scarabel

York University - Laboratory for Industrial and Applied Mathematics

Bushra Majeed

York University

Nicola Luigi Bragazzi

York University

James Orbinski

York University

Date Written: February 4, 2021

Abstract

Background. Public Health interventions have succeeded marginally to flatten the COVID-19 epidemic curve of the most recent wave in many regions. Several highly transmissible COVID-19 Variants of Concern (VOCs) have emerged internationally, with variable virulence and as-yet unclear antigenicity. Growing public fatigue highlights the importance of accurately quantifying the speed at which VOCs can replace the resident strain, to inform precise decision-making in terms of both timing and scale of interventions.

Methods. Using a simple Susceptible-Infected-Removed (SIR) model, we derive a formula calculating the duration for a VOC to increase its frequency from one level to another. We evaluate the impact of interventions on VOC-related variables.

Findings. After introduction of a VOC with a higher transmissibility than the resident strain, its prevalence increases exponentially, leading to eventual replacement by the VOC. Even if the outbreak caused by the resident strain has previously been brought under control, the epidemic is eventually going to increase exponentially, possibly after a transient declining phase. The initial VOC frequency, epidemic mean generation time, and reproduction number of the resident strain all contribute to determining the speed of VOC replacement and the resulting epidemic growth.

Interpretation. Following the introduction of a VOC, the risk of a sudden surge of the total cases is hidden behind a transient decline. Maintaining or enhancing Public Health interventions are vital to slowing down the VOC replacement, curbing the epidemic growth, and increasing VOC doubling time.

Note: Funding: The Canadian Institute of Health Research (CIHR) 2019 Novel Coronavirus (COVID-19) rapid research program.

Declaration of Interests: No competing interests.

Keywords: COVID-19, variant of concern, variant take-over, precision in decision making

Suggested Citation

Wu, Jianhong and Scarabel, Francesca and Majeed, Bushra and Bragazzi, Nicola Luigi and Orbinski, James, The Impact of Public Health Interventions on Delaying and Mitigating against Replacement by SARS-CoV-2 Variants of Concern (February 4, 2021). Available at SSRN: https://ssrn.com/abstract=3779007 or http://dx.doi.org/10.2139/ssrn.3779007

Jianhong Wu

York University - Laboratory for Industrial and Applied Mathematics ( email )

Canada

Francesca Scarabel

York University - Laboratory for Industrial and Applied Mathematics

4700 Keele Street
Toronto, Ontario M3J 1P3
Canada

Bushra Majeed

York University ( email )

4700 Keele Street
Toronto, Ontario M3J 1P3
Canada

Nicola Luigi Bragazzi (Contact Author)

York University ( email )

4700 Keele Street
Toronto, Ontario M3J 1P3
Canada

James Orbinski

York University

4700 Keele Street
Toronto, Ontario M3J 1P3
Canada

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