Direct evidence – COVID-19
We identified two modeling studies that used data from the currrent SARS-CoV-2 outbreak in China.45,46 Wen-Tao et al. used official data from Wuhan and employed a susceptible–infected–recovered (SIR) model for the spread of infectious diseases to predict the effectiveness of prevention and control measures of diverse intensity.45 Authors defined weak prevention and control measures as an unspecified combination of measures that reduces the contact rate and infection efficiency by 45% or less. In such a scenario, the authors predicted 4,719 cases with 739 deaths within three months in a population of 11·5 million inhabitants in Wuhan. Under strong prevention and control measures (defined as measures that succeed to reduce contact rate and infection efficiency by 50% or more) the number of infected people would go down to 3,088 with a death toll of 443. According to the authors, the key to control the COVID-19 epidemic is to focus on early prevention and control measures such as quarantine, social distancing, or the suspension of public transportation to reduce the contact opportunities between susceptible and infected people.45
The second Chinese study used a dynamic infectious disease model based on data of confirmed COVID-19 cases, fatalities, and cures published by the Chinese National Health Committee. Without presenting exact estimates, authors predicted a worsening of the epidemic’s severity if the government relaxes control measures (e.g., allow travelling), while the situation can be controlled by keeping strict control measures in place such as the community quarantine in Wuhan.46