Critical role of nosocomial transmission in the toronto sars outbreak.

We develop a compartmental mathematical model to address the role of hospitals in severe acute respiratory syndrome ( SARS ) transmission dynamics, which partially explains the heterogeneity of the epidemic. Comparison of the effects of two major policies, strict hospital infection control procedures and community-wide quarantine measures, implemented in Toronto two weeks into the initial outbreak, shows that their combination is the key to short-term containment and that quarantine is the key to long-term containment.