Brief Report: Incubation Period Duration and Severity of Clinical Disease Following Severe Acute Respiratory Syndrome Coronavirus Infection.

Virlogeux, Victor; Fang, Vicky J; Wu, Joseph T; Ho, Lai-Ming; Peiris, J S Malik; Leung, Gabriel M; Cowling, Benjamin J

BACKGROUND Few previous studies have investigated the association between the severity of an infectious disease and the length of incubation period. METHODS We estimated the association between the length of the incubation period and the severity of infection with the severe acute respiratory syndrome coronavirus, using data from the epidemic in 2003 in Hong Kong. RESULTS We estimated the incubation period of severe acute respiratory syndrome based on a subset of patients with available data on exposure periods and a separate subset of patients in a putative common source outbreak, and we found associations between shorter incubation period and greater severity in both groups after adjusting for potential confounders. CONCLUSIONS Our findings suggest that patients with a shorter incubation period went on to have more severe disease. Further studies are needed to investigate potential biological mechanisms for this association.