Early dynamics of transmission and control of COVID-19: a mathematical modelling study
Study highlights that as more cases arrive in international locations with similar transmission potential to Wuhan before control measures implemented, it is likely many chains of transmission will fail to establish initially, but might lead to new outbreaks eventually.
Source:
The Lancet Infectious Diseases
SPS commentary:
Study showed that COVID-19 transmission probably declined in Wuhan during late Jan 2020, coinciding with introduction of travel control measures.
A commentary notes that many questions remain unanswered and should be addressed with urgency, including the infectiousness of cases over the duration of their illness—particularly how much transmission could occur from people who are unaware that they have illness, including asymptomatic and mildly symptomatic people. It points out that initial reports suggest live virus can be recovered from asymptomatic or mildly symptomatic people, which is of great concern as it will make disease much harder to detect and therefore control. However, it is unknown what contribution such people make to the overall epidemic. It adds that the infection severity, including the infection-fatality rate across different ages and risk groups, must be established; early reports provide estimates of case fatality of 2·3% within China. It acknowledged that it is notoriously difficult to make such estimates early in an outbreak, and it is clear that not all infections become cases and studies of many tiers of severity will be needed to establish infection-fatality rates.