Modelling upper respiratory viral load dynamics of SARS-CoV-2

The relationships between viral load, severity of illness, and transmissibility of virus, have been the subject of intense interest since the start of the COVID-19 pandemic. They are fundamental to understanding pathogenesis and devising better therapeutic and prevention strategies. In this report we present within-host modelling to examine the viral load dynamics observed in the upper respiratory tract, drawing upon 2172 serial measurements from 605 subjects, collected from 17 different studies. We developed a mechanistic within-host model to describe viral load dynamics and host response, and also contrasted simpler mixed-effects regression analysis of peak viral load and its subsequent decline. The inclusion of age, sex, or disease severity of the subjects did not appreciably improve the fit of either the mechanistic model or the regression. In future work, this model will be used to connect viral load dynamics to underlying host traits, to better understand these complex interactions.