Elucidating the Early SARS-CoV-2 Dynamics and Concomitant Immune Responses in Unvaccinated Participants of an Intensely Sampled Longitudinal Surveillance Study

Abstract A comprehensive understanding of the SARS-CoV-2 infection dynamics and the ensuing host immune responses is needed to explain the pathogenesis as it relates to viral transmission. Here, we report results from an ongoing, longitudinal, workplace clinical surveillance study that address knowledge gaps surrounding SARS-CoV-2 in vivo kinetics, particularly in the earliest stages after exposure. Nine study participants who developed COVID-19 between November, 2020 and March, 2021 were monitored at high temporal resolution for three months in terms of viral loads as well as associated inflammatory biomarker and antibody responses. Analysis of the resulting datasets, supported by Bayesian modeling, allowed the underlying kinetic processes to be described, yielding a number of unexpected findings. Early viral replication is more rapid (median doubling time, 3.1 hours) than previously thought, shrinking the window between exposure and viral shedding. Results from our small study give a rare insight into the life-cycle of COVID-19 infection and hold a number of important biological, clinical, and public health implications.