https://orcid.org/0000-0001-9282-918X
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Abstract
Purpose
The severe pathogenic ancient-type COVID-19, SARS-CoV-2/WA-1/2020 was the predominant gene variant in early 2020 in Japan, however, its transmissibility was uncertain. The period before the public commenced using any personal protective equipment (PPE) was evaluating to describe the transmissibility of the SARS-CoV-2/WA-1/2020. We analyzed the secondary attack rate (SAR) among close contacts and the risk factor for SAR.
Methods
This retrospective cohort study included a total of 539 patients who were anticipated for the SARS-CoV-2/WA-1/2020 infection at Toho University Medical Center Omori Hospital from February to May 2020. We selected 54 patients with 1) exclude other pathogens infection, 2) include “Three Cs” condition: crowded places between distance< 6 feet, closed spaces indoor and close contact settings involving contact >15min with a person tested positive for SARS-CoV-2/WA-1/2020 without PPE. We evaluated alternative infection risks: the body mass index (BMI) and diabetes (DM) status (non-DM, pre-DM, and DM) as demographic determinants of transmissibility and infectivity of SARS-CoV2/WA-1/2020 cases during the incubation period.
Results
The calculated SAR was 79.3%. BMI was significantly associated with the PCR positivity rate, which was significant in the univariate (CI 95%, 1.02–1.51; P = 0.03) and multivariate (CI 95%, 1.02–1.60; P = 0.03) analyses. Comparing the different BMI groups, the highest BMI group (25.5−35.8 kg/m2) had an elevated risk of SAR compared to the lowest BMI group (14.0–22.8 kg/m2), with an odds ratio of 1.41 (95% CI, 1.02–1.59; P = 0.03). There were no significant differences in the risk of SAR among different DM statuses.
Conclusion
The transmissibility of SARS-CoV2/WA-1/2020 was high (79.3%) among household members without PPE who had “Three Cs” exposure. Although pre-DM and established DM did not confer a risk for transmissibility, higher BMI was associated with an increased risk of SAR.
Trial Registration
UMIN Clinical Trials Registry, UMIN0000 50905.
Data Sharing Statement
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Ethics/Ethical Approval
The study protocol was reviewed by the Japanese authorities in accordance with local regulations, followed by review and approval by the Ethics Committee of Toho University Omori Medical Center (M20263, 20135). This study was conducted in accordance with the International Conference on Harmonization Guidelines for Good Clinical Practice and the Declaration of Helsinki. This study was registered at the National University Hospital Medical Information Network (UMIN Clinical Trials Registry: UMIN0000 50905).
Written informed consent was obtained from all participants.
Acknowledgments
We are grateful to all the individuals who participated in this study. We would like to thank Editage (www.editage.com) for English language editing.
Author Contributions
All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.
Disclosure
Dr Fukumi Yoshikawa reports personal fees from Novo Nordisk Pharma Ltd., during the conduct of the study. All authors declare no other competing interests in this work.