Infection rate among close contacts of patients with coronavirus disease in Japan: a descriptive study and literature review.

Background: In Japan, on April 20, 2020, the definition of a close contact regarding coronavirus disease (COVID-19) was changed from a long-term contact time to a specified contact time of 15 min and from a contact distance of 2 m to 1 m. Objectives: We aimed to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rate among close contacts of patients with COVID-19 and determine the impact of the infection on transmission among close contacts. Methods: The numbers of SARS-CoV-2 tests, SARS-CoV-2-positive cases, and close contacts of patients with COVID-19 were assessed between March 2020 and February 2021 in Fukui Prefecture, Japan. The study period was subdivided into 3 periods. The second and third period contained data with the changed definition of close contact. Results: Overall, 32,238 SARS-CoV-2 tests were performed. There were 545 patients with COVID-19 and 1487 close contacts, of whom 267 tested positive. The highest infection rate occurred in period 3. Distance, protective measures, and contact time with COVID-19 patients influenced the increased infection rate. The infection rate showed a rising trend from 11.1% in period 1 to 19.2% and 20.0% in periods 2 and 3, respectively (Cochran-Armitage test; P < 0.004). Multivariate analysis revealed that female sex was an independent risk factor for infection of close contacts (odds ratio: 2.23; 95% confidence interval: 1.700-2.930). Conclusions: Female sex is a risk factor for transmission by close contacts. The rate of infection among close contacts may be associated with contact time, contact distance, and protective measures.

Attitudes toward cancer screening in regional Japan during the COVID-19 pandemic: An anonymous survey.

The coronavirus disease (COVID-19) pandemic has raised concerns about the impact of delayed health check-ups and cancer screenings on cancer diagnosis and treatment. This study aimed to investigate the awareness of cancer patients on future screening measures during the pandemic in rural Japan. An anonymized open-data survey was undertaken in Fukui Prefecture, a rural region of Japan, in 2021. Participants were asked about their cancer screening history, screening frequency during the pandemic, and reasons for not undergoing screening. Among the 1262 respondents, the proportion of patients who underwent cancer screening in 2020 during the pandemic was similar to the proportion who underwent regular (annual or biannual) screening in 2019 before the pandemic. Of those who underwent regular screening, 82% still underwent screening in 2020, while only 21% of those who had irregular screenings. The number of respondents who believed they were healthy and did not require screening increased over time, possibly due to restrictions on going out and refraining from activities during the pandemic. This study in rural Japan found that regular cancer screening prior to the pandemic was associated with a more positive attitude toward screening during the pandemic. Raising awareness about the importance of cancer screening and encouraging participation is crucial for promoting positive attitudes in the future. The findings highlight the need for continued efforts to ensure access to screening services during the pandemic and future public health emergencies.

False positive results in severe acute respiratory coronavirus 2 (SARS-CoV-2) rapid antigen tests for inpatients.

Severe acute respiratory syndrome coronavirus 2 rapid antigen detection (RAD) test kits are widely used as primary screening test in Japan because rapid diagnosis of coronavirus disease 2019 (COVID-19) is critical for infection control. We report cases with RAD test false-positive results in a ward for patients with disabilities. RAD tests potentially evoke hospital operational risk. It is desirable that performing PCR test appropriately when patients admitted to a medical treatment ward with COVID-19 symptoms instead of RAD test.

[Detection of tuberculosis infection using a whole blood interferon gamma assay in a contact investigation--evaluation using quantiFERon TB-2G].

OBJECTIVE: The purpose of this study was to evaluate the usefulness of a novel method of detecting tuberculosis infection, QuantiFERON TB-2G (QFT), in a large scale contact investigation when an outbreak of mass tuberculosis infection was suspected. SUBJECTS AND METHODS: The index case was a health-care worker who worked in a maternity hospital. The investigated contacts were categorized as follow according to the grade of closeness of contact; the "very close" contact group (11 subjects), the "close" contact group (33 subjects), and the "non-close" contact group (3,791 subjects). For the former two groups, tuberculin skin test (TST), chest X-ray examination and QFT were conducted. For the last contact group, TST and chest X-ray examination were conducted only to subjects who aged less than 29 years old, while only chest X-ray examination was conducted to those aged 30 years or older. The QFT test, i.e., a whole blood interferon-gamma assay using Mycobacterium tuberculosis-specific antigens, was performed to the "very close" and "close" contacts, and for strong tuberculin reactors among the "non-close" contacts. RESULTS: The number of infected subjects in the "very close" contact group, the "close" contact group, and the "non-close" contact group were 7, 7, and 277, respectively, based on TST results. On the other hand, the number of infected subjects in each group were 3, 2, and 5, respectively, based on the QFT test. CONCLUSION: If the indication of chemoprophylaxis was determined based on TST test, this case would have been regarded a large tuberculosis outbreak. However, the use of the QFT test greatly reduced the number of the infected persons, so that the possibility of such massive TB outbreak was denied. Thus, the use of QFT, with which TB infection could be detected more accurately, seems to be very beneficial in contact investigations.