An outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) occurred aboard the Diamond Princess cruise ship between her January 20 departure and late February 2020. Here, we used phylodynamic analyses to investigate the transmission dynamics of SARS-CoV-2 during the outbreak. Using a Bayesian coalescent-based method, the estimated mean nucleotide substitution rate of 240 SARS-CoV-2 whole-genome sequences was approximately 7.13 × 10 −4 substitutions per site per year. Population dynamics and the effective reproductive number (R e ) of SARS-CoV-2 infections were estimated using a Bayesian framework. The estimated origin of the outbreak was January 21, 2020. The infection spread substantially before quarantine on February 5. The R e peaked at 6.06 on February 4 and gradually declined to 1.51, suggesting that transmission continued slowly even after quarantine. These findings highlight the high transmissibility of SARS-CoV-2 and the need for effective measures to control outbreaks in confined settings.

AIM:To investigate the clinical and biochemical factors associated with visceral fat accumulation in the general population. METHODS:We enrolled 1004 subjects who underwent a medical health checkup between April 2008 and March 2009. The medical health checkup included the following tests: Height, body weight, waist circumference (WC), systolic blood pressure, diastolic blood pressure, urinalysis, blood-cell counts, blood chemistry, electrocardiography, chest radiography, and abdominal computed tomography (CT) for visceral fat accumulation. The patients' medical history and lifestyle factors were collected privately by nurses using a selfadministered questionnaire, and they included questions regarding physical activity, sleep duration, dietary habits, smoking, and alcohol consumption. visceral fat area (VFA) was defined as the sum of the intraperitoneal fat area at the level of the umbilicus with CT density in the range of -150 to -50 Hounsfield units. RESULTS:The mean age and body mass index (BMI) of the study subjects were 57.0 years and 24.4 kg/m 2 . In both male and females, vFA was significantly and Institutional review board statement: The study design was approved by the Ethics Committee of University of the Ryukyus, Okinawa, Japan.Informed consent statement: All subjects provided written informed consent for the use of their anonymized data for an epidemiological study. Conflict-of-interest statement:We have no conflict of interest. Data sharing statement: No additional data available.Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/ licenses/by-nc/4.0/ Retrospective study positively correlated with WC (r = 0.532, P < 0.01; r = 0.612, P < 0.01). Subjects with high levels of vFA were primarily male with significantly higher age, height, body weight, BMI, systolic blood pressure (BP), diastolic BP, and hemoglobin in all subjects (P < 0.05).A multivariate logistic regression analysis revealed that vFA had a positive relationship with age ≥ 56, BMI ≥ 25 kg/m 2 , and triglyceride level ≥ 149 in males (P < 0.05), whereas it had a positive relationship with age ≥ 58, BMI ≥ 24.4 kg/m 2 , high-density lipoprotein cholesterol level < 40 mg/dL, and current drinking in females (P < 0.05). CONCLUSION:These results suggest that gender differences exist in the clinical and biochemical parameters associated with visceral fat accumulation.

Okinawa Island, located in Southern Japan, has a higher prevalence rate of hepatitis C virus subtype 1a (HCV-1a) infection than that in mainland Japan. Okinawa has a history of US military occupation after World War II. To elucidate the transmission history of HCV-1a in Okinawa, 26 whole-genome sequences were obtained from 29 patients during 2011-2016. Phylogenetic trees were reconstructed to identify the origin and characteristics of HCV-1a in Okinawa with epidemiological information. A phylogenetic tree based on whole-genome sequencing revealed that all of the samples were located below the US branches. Additionally, we identified one cluster comprised of 17 strains (Okinawa, n = 16; United States, n = 1). The majority of the patients in this cluster were people who inject drugs (PWID), indicating the presence of a people who inject drugs (PWID) cluster. Subsequently, Bayesian analyses were employed to reveal viral population dynamics. Intriguingly, a phylodynamic analysis uncovered a substantial increase in effective population size of HCV-1a from 1965 to 1980 and a slight increase in mid-2000, which were associated with an increase in illicit drug use in Okinawa. The estimated divergence time of the PWID cluster was 1967.6 (1964.2-1971.1). These findings suggest that HCV-1a was introduced into Okinawa from the United States in the late 1960s, coincident with the Vietnam War. Subsequently, HCV-1a might have spread among the Japanese population with the spread of injecting drug use. Our study provides an understanding of HCV transmission dynamics in Okinawa, as well as the key role of PWID in HCV transmission.

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