Challenges in control of Covid-19: short doubling time and long delay to effect of interventions

Lorenzo Pellis; Francesca Scarabel; Helena B Stage; Christopher E Overton; Lauren H K Chappell; Katrina A Lythgoe; Elizabeth Fearon; Emma Bennett; Jacob Curran-Sebastian; Rajenki Das; Martyn Fyles; Hugo Lewkowicz; Xiaoxi Pang; Bindu Vekaria; Luke Webb; Thomas A House; Ian Hall

Planning of interventions usually relies on estimates of the basic reproduction number R 0 , defined as the average number of new infections generated by a single infected person within a susceptible population. Reported estimates of COVID-19 R 0 are highly variable, ranging from 1.4 to 6.49 [2, 11] , with the differences attributable to the variety of methods, model structures and parameter values (in particular, the estimated or assumed amount of presymptomatic transmission), as well as the data sources used. Most official sources settle in the range of 2-3 [3, [12] [13] [14] [15] , but these estimates mostly derive from early studies of the epidemic in Wuhan [16] [17] [18] , or the Diamond Princess Cruise ship [19] , and so are subject to important limitations: these include small amounts of data, uncertain or biased reporting of early cases in Wuhan, and the uniqueness of the specific settings in which they occurred.