Glucose Tolerance and the Risk Factors for Transmission in Japanese SARS-CoV-2/WA-1/2020 Epicenter: A Retrospective Study

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. 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. 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/m ) had an elevated risk of SAR compared to the lowest BMI group (14.0-22.8 kg/m ), 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. 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. UMIN Clinical Trials Registry, UMIN0000 50905.