The emergence of successive SARS-CoV-2 variants of concern during 2020-22 created a need to understand the drivers of such growth; this study by Russell, et al. (2024) uses a Bayesian model to reveal how a set of key covariates (the infecting variant, symptom status, age and number of prior exposures) affect viral kinetics at both individual and population levels.

The researchers found that age and number of prior exposures had a strong influence on peak viral replication. Older individuals and those who had at least five prior antigen exposures to vaccination and/or infection typically had much lower levels of shedding. Moreover, they found evidence of a correlation between the speed of early shedding and duration of incubation period when comparing different VOCs and age groups. The authors say their findings illustrate the value of linking information on participant characteristics, symptom profile and infecting variant with prospective PCR sampling, and the importance of accounting for increasingly complex population exposure landscapes when analyzing the viral kinetics of VOCs.

Reference: Russell TW, et al. (2024). Combined analyses of within-host SARS-CoV-2 viral kinetics and information on past exposures to the virus in a human cohort identifies intrinsic differences of Omicron and Delta variants. PLOS Biology.