The article by Lipsitch et al. provides a detailed analysis of the transmission dynamics and control measures for Severe Acute Respiratory Syndrome (SARS). Using epidemiological data from Singapore and other settings, the authors estimate the reproductive number (R0) of SARS, which is the average number of secondary cases generated by a single infectious case in a fully susceptible population. They find that a single infectious case of SARS can infect about three secondary cases in a population without control measures. Public health interventions, such as isolation and quarantine, are expected to significantly reduce the size of the epidemic. The study also examines the impact of superspreading events and asymptomatic cases on transmission. The authors use mathematical models to assess the effectiveness of control measures, including the reduction in the infectious period and the quarantine of contacts. They conclude that a combination of shortening the time from symptom onset to isolation and effective contact tracing and quarantine can effectively contain SARS. The findings highlight the importance of early and stringent control measures to prevent widespread transmission.The article by Lipsitch et al. provides a detailed analysis of the transmission dynamics and control measures for Severe Acute Respiratory Syndrome (SARS). Using epidemiological data from Singapore and other settings, the authors estimate the reproductive number (R0) of SARS, which is the average number of secondary cases generated by a single infectious case in a fully susceptible population. They find that a single infectious case of SARS can infect about three secondary cases in a population without control measures. Public health interventions, such as isolation and quarantine, are expected to significantly reduce the size of the epidemic. The study also examines the impact of superspreading events and asymptomatic cases on transmission. The authors use mathematical models to assess the effectiveness of control measures, including the reduction in the infectious period and the quarantine of contacts. They conclude that a combination of shortening the time from symptom onset to isolation and effective contact tracing and quarantine can effectively contain SARS. The findings highlight the importance of early and stringent control measures to prevent widespread transmission.