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Epidemiological study and health management of an imported incident of COVID–19 asymptomatic cases in Haikou, China: A retrospective case series
Fan Zhang1, Guo-Tian Lin2, Yu-Ming Jin3, Tao Wu4, Jun-Cai Chen2, Li-Chun Fan5, Zhi-Yue Lv6, Wei Xiang7
1 NHC Key Laboratory of Control of Tropical Diseases; One Health Research Center, Hainan Medical University, Haikou 571199, China
2 Laboratory of Tropical Environment and Health, International School of Public Health and One Health, Hainan Medical University, Haikou 571199, China
3 Hainan Provincial Center for Disease Control and Prevention, Haikou 570203, China
4 Hainan Affiliated Hospital of Hainan Medical University, Haikou 570311, China
5 Department of Child Health Care, Hainan Women and Children's Medical Center, Children's Hospital of Hainan Medical University, Haikou 570206, China
6 NHC Key Laboratory of Control of Tropical Diseases; Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Medical University, Haikou 571199, China
7 NHC Key Laboratory of Control of Tropical Diseases, Hainan Medical University, Haikou 571199, China
Correspondence Address:
Li-Chun Fan
Department of Child Health Care, Hainan Women and Children's Medical Center, Children's Hospital of Hainan Medical University, Haikou 570206
China
Wei Xiang
NHC Key Laboratory of Control of Tropical Diseases, Hainan Medical University, Haikou 571199
China
Zhi-Yue Lv
NHC Key Laboratory of Control of Tropical Diseases; Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Medical University, Haikou 571199
China
 Source of Support: This study was funded by Hainan Major Science and Technology Projects (No. ZDKJ2019010 and hxk200020), the Key Research and Development Program of Hainan Province (Grant No. ZDYF2020120), the Specific Research Fund of the Innovation Platform for Academicians of Hainan Province (Grant No. YSPTZX202133), and the Major Science and Technology Program of Hainan Province (Grant No. ZDKJ202003 and ZDKJ2021035), Conflict of Interest: None
DOI: 10.4103/2773-0344.361971
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Background: To control the imported risks brought by all international arrivals, China Customs has implemented strict closed-loop health management policy called “three checks, three screenings and one transfer”. This study provides epidemiological evidence for prevention and control measures on imported cases of asymptomatic infections and describes the current COVID-19 prevention and control system on imported risks in China.
Methods: We retrospectively analyzed an imported incident of three asymptomatic carriers. Serum SARS-CoV-2 IgM and IgG antibodies were detected by chemiluminescence and gold immnnochromatography(GICA).
Results: Three cases were reported positive for SARS-CoV-2 nucleic acid on their arrival, total antibodies and IgG, but negative for IgM. The Ct values of cases A, B and C were 34/36/36, 32/33/32 and 25/31/29, respectively. There were 10726434 pair-end reads sequenced for case C, and approximate 80% reads were aligned to the hCoV-19/Wuhan/IVDC-HB-01/2019 genome (EPI_ISL_402119). The viruses of case A and C were homologous and came from the SARS-CoV-2 variant.
Conclusion: Serum antibody IgM and IgG tests are recommended for international travelers from epidemic areas. The “three checks, three screenings and one transfer” policy implemented at custom’s entry points was effective in COVID-19 prevention and control.
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