Between 10 and 12 January when there were no new cases reported, the Wuhan Municipal Health Commission announced that no new cases of 2019-nCoV infection were identified with illness onset after 3 January. As at 11 January, more than 700 close contacts were under medical surveillance, more than half being healthcare workers (HCWs), with no infections being identified [15]. Among the first 41 confirmed cases, approximately 70% reported exposure to the Southern China Seafood Wholesale Market [16]. Using the method described by Cauchemez et al. [17], assuming that the market was the only source of zoonotic infections, we estimated R 0 to be 0.3 (95% confidence interval (95% CI): 0.17–0.44).