Case study: An outbreak of COVID-19 in a large meal kit factory in Sydney, Australia

The Delta variant of the SARS-CoV-2 virus caused a marked upsurge in COVID-19 cases in Western Sydney in mid- 2021 and was accompanied by a large outbreak in one of the largest food processing plants. Innovative methods were used to identify cases, halt the ongoing epidemic, and ensure that the plant was protected from future outbreaks.

The plant was run by a major food packaging and delivery company employing approximately 350 people, of which a high proportion were casual workers. Eighty-seven percent of staff came from parts of Sydney identified at the time with elevated COVID-19 case numbers. Production floor areas were refrigerated at between 4°C and 5°C. During their shifts, workers stood side-by-side approximately one metre apart.

Recognising the high risk of transmission, the company instituted worker temperature and symptom screening on entry to the plant and soon after mandated the use of surgical masks and gloves as personal protective equipment.

The first two positive cases identified were confirmed to have been at work during their infectious period. In response, the company required all workers who had been within 10 metres of a positive case for more than 15 minutes to isolate for 14 days. They required all other workers on the same shift as a confirmed case to leave work, be PCR tested, and to isolate until they had received a negative result.

To control the outbreak some production lines were closed, production was transferred to less crowded assembly lines, and a night shift was introduced. A vaccination drive resulted in over 75% of the workforce being vaccinated by the end of August. Rapid antigen testing of all employees entering the workplace was introduced on 22 August. Mandated mask wearing compliance rates were low at first, however, after a series of efforts to increase uptake, mask usage became ubiquitous throughout the plant. Newly reported cases had declined dramatically by the end of August.

This large outbreak was likely attributed to a number of factors, including moderate physical labour, crowded production floor, cold environment, casual workforce drawn from communities with high background levels of COVID-19, and high numbers of asymptomatic staff attending work during their infectious period. Actions including masks, changed working practices and schedules, vaccination, and education finally brought the outbreak under control.

This case study demonstrates the importance of proactive implementation of a range of interventions to reduce the likelihood of respiratory epidemics in refrigerated food processing and packaging workplaces.