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