Figure shows an example of one cluster with five generations of transmission G1—G5 ; all clusters were defined in this way.
This study has limitations.
These characteristics make Wanzhou a suitable example for better understanding the transmission dynamics and risk factors of SARS-CoV-2 infection, as well as the effectiveness of control measures, for both researchers and policy makers in countries and cities that are heavily hit by the COVID-19 outbreak.
The date of symptom onset for symptomatic cases is marked by a solid triangle.
Thus, our G1-to-G2 reproductive number was lower than model-based basic reproductive numbers that do not consider quarantine for close contacts ,.
Of the 183 confirmed cases, 20 symptomatic and 7 asymptomatic individuals were unable to trace their previous or next generations of transmission and thus could not be clustered.
A case is considered active from the date of contact until becoming negative by RT—PCR and is counted as an active case throughout this period.
Although differences in the age distribution between symptomatic cases, asymptomatic cases and negative close contacts were observed Supplementary Table , risk for SARS-CoV-2 infection did not differ by sex or age Table.