Abstract：Objective To investigate 2019 novel coronavirus (2019-nCoV) infection in key population in Changde city so as to provide evidence for formulating prevention and control strategies and measures. Methods According to Protocol onPrevention and Control of COVID-19 issued by the National Health Commission, we collected nasopharyngeal swabs from suspected cases and close contacts of confirmed cases and asymptomatic infected persons reported by fever clinics in Changde city from January 22 to February 25 in 2020, and conducted nucleic acid testing and epidemiologicalinvestigation and analysis. Results There were 76 (18.4%) cases with positive nucleic acid test among 413 suspected cases reported by fever clinics, and the infection rate of suspected cases in different counties, cities and districts showed statistically significant difference (χ2=29.91, P<0.001). Among the 2,130 close contacts, 21 tested positive for the nucleic acid, with a positive rate of 0.99%. The infection rates of close contacts in different counties, cities and districts were statistically different(χ2=25.31, P<0.005). No statistically significant difference was found in the age distribution between the sexes (χ2=1.79, P>0.05). 82 of 97 positive cases turned into confirmed cases as of February 25, including 41 male and 41 female cases. The age distribution was between 22 and 81 years, mainly including youth group aged 15-44 years(36/82,43.9%) and middle-aged group aged 45-64 years(38/82,46.3%). There were 10 severe cases, the male-to-female ratio was 9∶1, and a statistically significant difference was found in the severe case rate between the sexes(χ2=7.29, P<0.01). The average age of mild patients was (45.4±12.8) years old, while that of severe patients was (57.7±14.5) years old, showing a statistically significant difference between the two groups(t=7.86,P<0.01). The average ages of clustered cases (n=43) and sporadic cases (n=39) were (50.7±13.8) years old and (42.7±12.3) years old, respectively, showing statistically significant difference between the two groups (t=7.65, P<0.01). The severe case rate in patients with a history of travel or residence in Wuhan city or Hubei province was 12.2%(6/48), whereas that in patients without a history of travel or residence in Wuhan city or Hubei Province was 11.8%(4/34), without statistically significant difference in the severe case rate between the two groups (χ2=0.01,P>0.05). Conclusions The key population in Changde city is generally susceptible to 2019-nCoV, and the confirmed cases are mainly young and middle-aged people. The risk for developing severe illness is higher with the increasing age. Male patients are more likely to develop severe illness than female ones.
2020, Vol. 27 
