Analysis of a tuberculosis outbreak in an office: Hokkaido, Japan, 2019-2020.

Background: In August 2018, a male worker (Pt1) in an office was diagnosed with smear-positive pulmonary tuberculosis (TB). This study aims to characterize the cases found in the TB outbreak in the office. Methods: The risks of TB disease or infection were compared among the staff members by seating locations. Results: A total of 116 current and ex-staff members were investigated, among whom 13 patients with active TB, including Pt1, and 20 with latent TB infection were found by the end of 2020. One-third of the seating groups located at one end of the office that Pt1 belonged to had the highest risk of TB disease (30.8%, 95% confidence interval [CI]: 14.3%-51.8%) and infection (61.5%, 95% CI: 40.6%-79.8%) with a high relative risk of TB infection (6.2, 95% CI: 2.0-18.8) compared to another one-third of the seating groups at the other end of the office that had the lowest risk of active TB (0%, 95% CI: 0%-11.6%) and TB infection (10.0%, 95% CI: 2.1%-26.5%). Conclusion: The seating groups that Pt1 belonged to had the highest risk of TB disease and infection because the staff members in the groups were exposed to the air containing TB bacilli from Pt1. Local health offices should initiate active case finding using chest X-rays as soon as they are notified of a sputum smear-positive TB case if the delay of the diagnosis is longer than three months.

Singing Is a Risk Factor for Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A Case-Control Study of Karaoke-Related Coronavirus Disease 2019 Outbreaks in 2 Cities in Hokkaido, Japan, Linked by Whole Genome Analysis.

Background: Singing in an indoor space may increase the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We conducted a case-control study of karaoke-related coronavirus disease 2019 (COVID-19) outbreaks to reveal the risk factors for SARS-CoV-2 infection among individuals who participate in karaoke. Methods: Cases were defined as people who enjoyed karaoke at a bar and who tested positive for SARS-CoV-2 by reverse-transcription polymerase chain reaction between 16 May and 3 July 2020. Controls were defined as people who enjoyed karaoke at the same bar during the same period as the cases and tested negative. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. ORs of key variables adjusted for each other were also estimated (aOR). Results: We identified 81 cases, the majority of whom were active elderly individuals (median age, 75 years). Six cases died (case fatality ratio, 7%). Among the cases, 68 (84%) were guests, 18 of whom had visited ≧2 karaoke bars. A genome analysis conducted in 30 cases showed 6 types of isolates within 4 single-nucleotide variation difference. The case-control study revealed that singing (aOR, 11.0 [95% CI, 1.2-101.0]), not wearing a mask (aOR, 3.7 [95% CI, 1.2-11.2]), and additional hour spent per visit (aOR, 1.7 [95% CI, 1.1-2.7]) were associated with COVID-19 infection. Conclusions: A karaoke-related COVID-19 outbreak that occurred in 2 different cities was confirmed by the results of genome analysis. Singing in less-ventilated, indoor and crowded environments increases the risk of acquiring SARS-CoV-2 infection. Wearing a mask and staying for only a short time can reduce the risk of infection during karaoke.