An outbreak of COVID-19 in a jewelry store in Tiruchirappalli, Tamil Nadu, India, 2020.

Dear Editor Investigating nonhealthcare workplace COVID-19 disease clusters, could give insight into developing preventive strategies for COVID-19 spread in the postlockdown period.[1] A popular five-storied jewelry store in the heart of Tiruchirappalli city had around 1000 employees. The store had provided dormitory accommodation for their employees. On June 25, 2020, six store employees reported fever and cough to their employer, and upon testing by reverse transcription–polymerase chain reaction (RT-PCR), all six were positive for COVID-19. We confirmed and investigated this outbreak of COVID-19 to identify risk factors and propose control measures. We defined a probable case of COVID-19 as an individual with fever, sore throat, cough, breathlessness, myalgia, or loss of taste or smell.[2] An individual with a positive RT-PCR test report for COVID-19 was considered a confirmed case. We defined a contact of COVID-19 cases as a person who had contact with a confirmed COVID-19 case patient. We actively searched for the cases and their contacts and tested them for COVID-19 using RT-PCR. We calculated the attack rate by age and gender. We also described the characteristics of the case patients by frequencies. We conducted an unmatched case–control study to identify the risk factors of COVID-19 in this workplace setting. We considered individuals positive for COVID-19 by RT-PCR test as a “Cases”, and those who were negative for COVID-19 by RT-PCR test as “Controls”. We selected the cases and controls by simple random sampling. We explored compliance to face mask usage, hand hygiene, and social distancing as exposures. We used a semi-structured data collection tool and collected the data using telephonic interviews using a mobile-based application. We presented the association as odds ratios (ORs) with a 95% confidence interval (CI) and did a multivariate analysis to get adjusted ORs (AORs) and 95% CI. Of the 727 individuals at risk, 386 (53%) were affected by COVID-19. Among them, 239 (62%) were staff and 292 (76%) were males. The affected individuals’ mean (standard deviation) age was 36.3 (13.6) years. The attack rate among the females (71%, [94/133]) was higher than the males (49%, [292/594], P < 0.001). The attack rate was highest for the 45–59 age group (63%, [104/166], P 0.008). We recruited 160 cases and 160 controls into the study. COVID-19 infection was higher among individuals who dined with their colleagues (65%, [93/144]) than those who did not (38%, [67/176], AOR 2.91 [95% CI: 1.67 - 5.05], P < 0.001). We found the face mask to be 95% protective against being affected by COVID-19 (Adjusted OR 0.05, [95% CI: 0.03 – 0.11], P <0.001, Table 1).Table 1: Factors associated with the COVID-19 outbreak in June 2020 among the staff of a jewelry store in Tiruchirappalli, Tamil Nadu, India, case-control study (n=320)The risk of COVID-19 infection increases with close contact with COVID-19 cases and activities such as eating together and attending any gatherings.[3,4] Thus, noncompliance with face mask usage and social distancing norms likely led to the outbreak of COVID-19 in this jewelry store. The district team’s extensive testing and contact tracing helped track the at-risk individuals and controlled the outbreak. We recommend that employees follow COVID-appropriate behavior at the workplace and in group accommodations. Financial support and sponsorship The study was a part of the first author’s India Epidemic Intelligence Service - FETP Fellowship’s core learning activities and is funded by the Indian Council of Medical Research – National Institute of Epidemiology, Chennai, Tamil Nadu, India. Conflicts of interest There are no conflicts of interest.