*2.2. Outbreak Detection and Case Finding*

Notification of the outbreak was received by the LMPHU from the pathology provider with three confirmed cases identified; an assessment of the site was performed by public health officers in the LMPHU identifying an additional eleven symptomatic workers. Confirmed outbreak cases were epidemiologically linked workers with a positive COVID-19 test through either polymerase chain reaction (PCR; confirmed cases) or rapid antigen test (RAT; probable cases). Epidemiologically linked cases were cases who had contact with other previously confirmed cases for at least 15 min or 2 h cumulatively, within 48 h of either symptom onset or date of sample collection in asymptomatic cases [13]. Cultural and language translation services were employed to ensure speedy case confirmation and accurate information collection to facilitate contact-tracing. Infections were considered active within seven days of testing positive, as per DH case-definition guidelines [13].

#### *2.3. Analysis*

Case, contact, and site assessments were conducted over the telephone and via Microsoft Teams application. Data collected were securely stored and managed through the Victorian Department of Health TREVI system. Descriptive analysis of cases was performed in Microsoft® Office Excel and R Studio using the EpiCurve package.
