Seroprevalence of SARS‐CoV‐2 in Utsunomiya City, Greater Tokyo, after the first pandemic in 2020

BackgroundA seroepidemiological study was conducted on a random sample of households in Utsunomiya City, Tochigi Prefecture, Greater Tokyo, Japan, to assess the seroprevalence of SARS‐CoV‐2.MethodsThe level of IgG antibodies in the blood of the recruited subjects was assessed using chemiluminescence immunoassay analysis. In addition, the population‐based prevalence of SARS‐CoV‐2 was estimated.ResultsThree positive afebrile cases were confirmed. The estimated unweighted prevalence and weighted prevalence of SARS‐CoV‐2 infection were 0.40% and 1.23%, respectively.ConclusionsThis study suggests that the prevalence of SARS‐CoV‐2 may have been underestimated. Wider testing strategies may lead to revealing more SARS‐CoV‐2 cases.

Interplay between social isolation and loneliness and chronic systemic inflammation during the COVID-19 pandemic in Japan: Results from U-CORONA study.

In the face of the global coronavirus disease 2019 (COVID-19) pandemic, billions of people were forced to stay at home due to the implementation of social distancing and lockdown policies. As a result, individuals lost their social relationships, leading to social isolation and loneliness. Both social isolation and loneliness are major risk factors for poor physical and mental health status through enhanced chronic inflammation; however, there might be an interplay between social isolation and loneliness on the association with chronic inflammation. We aimed to clarify the link between social relationships and inflammation in the context of the COVID-19 pandemic by distinguishing whether social isolation only, loneliness only, or both were associated with chronic inflammation markers among community-dwelling adults. The data of 624 people (aged 18-92 years, mean 51.4) from the Utsunomiya COVID-19 seROprevalence Neighborhood Association (U-CORONA) study, which targeted randomly sampled households in Utsunomiya city, Japan, were analyzed. Social isolation was assessed as a structural social network by asking the number of social roles they have on a daily basis. Loneliness was measured with the UCLA loneliness scale. As chronic inflammation biomarkers, neutrophil-to-lymphocyte ratio (NLR) and the concentration of high-sensitivity C-reactive protein (CRP) were measured. Generalized estimating equations method was employed to take into account the correlations within households. Isolated-Lonely condition (i.e., being both socially isolated and feeling lonely) was associated with higher NLR among men (B = 0.141, 95%CI = -0.01 to 0.29). Interestingly, Nonisolated-Lonely condition (i.e., not socially isolated but feeling lonely) was associated with lower CRP among women (B = -0.462, 95%CI = -0.82 to -0.10) and among the working-age population (B = -0.495, 95%CI = -0.76 to -0.23). In conclusion, being both socially isolated and feeling lonely was associated with chronic inflammation. Assessing both social isolation and loneliness is critical for proper interventions to mitigate the impact of poor social relationships on health, especially in the context of the COVID-19 pandemic.

Validity of Clinical Symptoms Score to Discriminate Patients with COVID-19 from Common Cold Out-Patients in General Practitioner Clinics in Japan.

OBJECTIVE: Coronavirus disease 2019 (COVID-19) has spread worldwide, including Japan. However, little is known about the clinical symptoms which discriminate between COVID-19 and non-COVID-19 among outpatients in general practitioner clinics, which is important for efficient case detection. The aim of this study was to investigate the clinical symptoms to discriminate between COVID-19 and non-COVID-19 cases among outpatients in general practitioner clinics during the second wave of the COVID-19 pandemic in Japan in August 2020. METHODS: The records of 360 patients who visited a clinic with suspicion of infectious disease and underwent COVID-19 PCR test between 1 and 14 August 2020 were used. The patients filled out a questionnaire on possible clinical symptoms and transmission routes. Multivariate logistic regression was used to investigate the association between clinical symptoms and COVID-19 status. RESULTS: COVID-19-positive patients were 17 (4.7%). Multiple logistic regression analyses showed that anosmia (odds ratio (OR), 25.94 95% confidence interval (CI), 7.15-94.14; p < 0.001), headache (OR, 3.31 95% confidence interval (CI), 0.98-11.20; p = 0.054), sputum production (OR, 3.32 CI, 1.01-10.90; p = 0.048) and history of visiting an izakaya or bar (OR, 4.23 CI, 0.99-18.03; p = 0.051) were marginally significantly associated withbeing COVID-19 positive. This model showed moderate predictive power (area under receiver operating characteristic curve = 0.870 CI, 0.761 to 0.971). CONCLUSIONS: We found that anosmia, headache, sputum production, history of visiting an izakaya or bar were associated with COVID-19, which can be used to detect patients with COVID-19 in out-patient clinics in Japan. The findings of this study need to be verified in other clinics and hospitals in Japan and other countries with universal healthcare coverages.