Presymptomatic Transmission and Diverse Progression of Familial Clustering Covid-19 Cases in Zhoushan, China

Abstract

Background Novel coronavirus disease 2019 (COVID-19), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-caused emerging infectious disease, firstly identified in Wuhan (Hubei, China), is pandemic. However, data concerning presymptomatic SARS-CoV-2 transmission and disease diversity among family members are limited. Herein, We investigated the epidemiological and clinical characteristics of presymptomatic transmission-caused familial clustering cases of SARS-CoV-2 infection in Zhoushan island, China. Methods All family members were tested for SARS-CoV-2 genomic RNA by quantitative reverse transcription PCR in 3 different samples and serum antibody immunoglobin M (IgM) and IgG against SARS-CoV-2. Exposure identification, laboratory test, and imaging were performed according to the national guideline of COVID-19 (7th edition, China). Results Of the 6 cases, index case who ever met his relative with COVID-19 from Xianning, Hubei on January 26–31, 2020, transmitted SARS-CoV-2 to his family members in Zhoushan via visiting family during January 31 and February 3, 2020. The index was identified as common-type COVID-19 on February 6, 2020. All 5 family members were infected with SARS-CoV-2. Of those, a 7-year-old girl was an asymptomatic carrier whereas her grandparents, especially her grandfather, were very sick. Case 6 (grandfather) remained positive for SARS-CoV-2 RNA in his sputum specimen in subsequent 2 months. Case 2 (mother) tested negative for SARS-CoV-2 RNA in all samples but positive for IgM and IgG to SARS-CoV-2 since February 9, 2020. Conclusions Presymptomatic transmission of SARS-CoV-2 causes familial cluster of COVID-19. Exposed to the same source of infection, family members present their differences in disease severity and viral clearance.