Abstract
Inferring the relative strength (i.e. the ratio of reproduction numbers) and relative speed (i.e. the difference between growth rates) of new SARS-CoV-2 variants is critical to predicting and controlling the course of the current pandemic. Analyses of new variants have primarily focused on characterizing changes in the proportion of new variants, implicitly or explicitly assuming that the relative speed remains fixed over the course of an invasion. We use a generation-interval-based framework to challenge this assumption and illustrate how relative strength and speed change over time under two idealized interventions: a constant-strength intervention like idealized vaccination or social distancing, which reduces transmission rates by a constant proportion, and a constant-speed intervention like idealized contact tracing, which isolates infected individuals at a constant rate. In general, constant-strength interventions change the relative speed of a new variant, while constant-speed interventions change its relative strength. Differences in the generation-interval distributions between variants can exaggerate these changes and modify the effectiveness of interventions. Finally, neglecting differences in generation-interval distributions can bias estimates of relative strength.
Keywords: COVID-19; SARS-CoV-2; generation interval; reproduction number; variants of concern.
【저자키워드】 COVID-19, SARS-CoV-2, variants of concern, Reproduction number, generation interval, 【초록키워드】 vaccination, pandemic, social distancing, variant, variants of concern, Contact tracing, Intervention, variants, Reproduction number, Effectiveness, distribution, change, Critical, Invasion, growth rates, infected individual, infected individuals, reproduction numbers, assumption, transmission rates, transmission rate, isolate, difference, new SARS-CoV-2, Course, proportion, changes in, reduce, fixed, modify, exaggerate, bias estimate, 【제목키워드】 variant, new SARS-CoV-2,