COVID-19,caused by SARS-CoV-2[1,2],has been contained in China through stringent non-pharmaceutical interventions.Border control and quar-antine have effectively prevented the virus from being spread by infected travellers,but the risk of resurgence caused by other routes of introduction and transmission remains unclear,and current strategies to prevent resurgence could be flawed.Since July,SARS-CoV-2 RNA contaminations in frozen food imported from countries with ongoing epidemics have been reported in nine provinces in China[3,4].However,there is no robust evidence of COV1D-19 outbreaks initiated by environment-to-human transmission.Here we add to evidence of such transmission by investigating the recent COVID-19 resurgence in Beijing.