K - College of Natural Resources - University of California, Berkeley

everywhere. These robust conclusions also provide guidance for future outbreaks of
emerging pathogens, particularly those exhibiting a tendency for nosocomial spread.
Our analysis identifies healthcare workers (HCWs) as critical targets for control
efforts. Their status is analogous to high-activity “core groups” in sexually-transmitted
disease epidemics, but the deliberate importation of SARS cases from the background
community adds a twist to this established paradigm. HCWs are thus exposed to a local
prevalence much higher than that in the community-at-large, and as a result measures
which reduce transmission within the hospital have the greatest impact on the
reproductive number (R) of the epidemic. Hospital-wide precautions (η) have the
strongest effect on R, followed by specific precautions for isolating SARS patients (κ).
This finding is bolstered by the detailed account of Dwosh et al. (2003) of a
comprehensive and effective response by a community hospital near Toronto. A
dedicated SARS ward was established (under negative air pressure to prevent aerosol
spread to other parts of the hospital) and private rooms provided for each SARS patient
(also under negative pressure); these measures correspond to reduced κ in our model.
Intensive barrier and contact precautions were practiced by all hospital staff at all times
(corresponding to η