Citywide Nucleic Acid Screening of SARS-CoV-2 Infections in Post-lockdown Wuhan, China: Results and Implications

Abstract

Background: After the outbreak of Coronavirus disease in 2019 (COVID-19), stringent lockdown measures were imposed in Wuhan between January 23, 2020 and April 8, 2020. To provide evidence on the post-lockdown risk of COVID-19 epidemic in Wuhan, the city government conducted a citywide nucleic acid screening of SARS-CoV-2 infection between May 14 and June 1, 2020. Methods: All city residents aged ≥6 years were potentially eligible to participate the screening programme. The rate of detection of asymptomatic infected cases was calculated, and their demographic and geographic distributions were investigated. ArcGIS 10.0 was used to draw a geographic distribution of asymptomatic infected persons. Results: The screening programme recruited a total of 9,899,828 persons (response rate, 92.9%). The screening found no newly confirmed patients with COVID-19, and identified 300 asymptomatic infected cases (detection rate 0.303/10,000). In addition, 107 of 34,424 previously recovered patients with a history of COVID-19 diagnosis were tested positive (relapse rate, 0.31%). Virus culture of SARS-CoV-2 was negative for all 300 asymptomatic cases and all 107 recovered COVID-19 patients. A total of 1,174 close contacts of asymptomatic cases were traced and all of them had a negative nucleic acid testing result. Conclusions: Prevalence of COVID-19 nucleic acid test positivity was very low in the Wuhan general population, in recovered cases and in contacts of asymptomatic cases, five to eight weeks after the end of lockdown. These findings help resolve concerns about the post-lockdown risk of COVID-19 epidemic, and promote the recovery of economy and normal social life in Wuhan.

Population‐based prevalence surveys during the Covid‐19 pandemic: A systematic review

“…The authors of 15 (46.9%) of the 32 studies that used serological tests reported their own validation test performance, while in 13 (40.6%), the validation performed by other studies or by the manufacturer was described. Excluding Wuhan's (China) screening programme 17 that tested 9,899,828, at least 394,090 individuals were tested in the other 36 studies that reported the number of tests. However, this number was highly variable among studies (mean: 10,946.94, median: 1990, standard deviation (SD): 27,382.34).…”

“…Some studies demonstrated a disproportionate seroprevalence in black communities, 24,40,42–44,46,47,51 multiracial, Hispanic, Indigenous, and Asian persons, 24,34,38,39,44,46 as well as in public‐facing workers 17,24,43 and slums population 18,45 . These data show the disparities that minority communities face to access healthcare systems, arisen from a complex relationship of social, environmental, economic and structural inequities 60,61 .…”

Population-based prevalence surveys during the COVID-19 pandemic: a systematic review

“…Some studies demonstrated a disproportionate seroprevalence in black communities ( 24,40,42-44,46,47,51 ), multiracial, hispanic, indigenous, and asian persons ( 24,38,39,43,44,46 ), as well as in public-facing workers ( 17,24,43 ), and slums population ( 18,45 ). These data show the disparities that minority communities face to access healthcare systems, arisen from a complex relationship of social, environmental, economic, and structural inequities ( 60,61 ).…”