Quantifying dynamics of SARS-CoV-2 transmission suggests that epidemic control and avoidance is feasible through instantaneous digital contact tracing

Luca Ferretti; Chris Wymant; Michelle Kendall; Lele Zhao; Anel Nurtay; David G Bonsall; Christophe Fraser

27.5% -45%), which can be interpreted as the fraction of pre-symptomatic transmission events out of pre-symptomatic plus symptomatic transmission events. This mean probability over all pairs approximates our prior, but the bimodal distribution of individual probabilities in Fig. 1 shows that these are typically far from the prior, i.e., the data are strongly informative. Uncertainty in the value of this fraction is shown in We decompose ( ) into four contributions that reflect our categorization above, namely asymptomatic transmission, pre-symptomatic transmission, symptomatic transmission, and environmental transmission. The area under the curve of one of these contributions gives the mean total number of transmissions over one full infection, via that route -asymptomatic, pre-symptomatic, symptomatic or environmental -which we define to be RA, RP, RS and RE respectively. The sum of these is R0.