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Investigation of a Cluster of COVID-19 Cases with Four Generations of Transmission in Chongqing, China
13 Pages Posted: 1 Jun 2020
More...Abstract
Background: To better understand the disease transmission pattern, a cluster of coronavirus disease 2019 (COVID-19) cases, with four generations of transmission, was investigated in Chongqing, China.
Methods: The epidemiological and clinical data of infected cases and antibody testing of close contacts of the cluster were collected and evaluated. The attack rate, infection rate, incubation period, serial intervals, and IgM and IgG detection rates were reported.
Findings: Between January 23 and March 2, 2020, there were 180 persons were involved and traced in the cluster with two imported cases. Among the 178 close contacts, there were 11 confirmed cases and 3 asymptomatic infections, which included mostly family members and work colleagues. The median incubation period of infection was 12 days (3-25 days). The median serial interval was 8 days (5 to 14 days). The infection rates of each generation were 21·9%, 6·5%, 3·3%, and 0%. Of the 118 close contacts tested for antibodies, 13 contacts (11·0%) had positive IgM or IgG or both positive.
Interpretation: With each new generation of transmission, the infection rates progressively declined. The symptom onset of the secondary generation maybe earlier than the primary generation demonstrating that epidemiological investigation and tracing of close contacts of the cases is needed. The antibody test maybe a complementary method to identify lost infections demonstrating further nucleic acid test.
Funding Statement: None
Declaration of Interests: The authors declare no competing interests.
Ethics Approval Statement: The study was approved by the Ethics Committee of Chongqing Medical University.
Keywords: Cluster, COVID-19, transmission, infection rate
Suggested Citation: Suggested Citation