Officials confirmed 64 farm outbreaks associated with 2,202 confirmed cases of COVID-19 in Ontario during 2020, according to new data presented in a CCDR report from the Canadian government, suggesting farms—especially greenhouse farms—played a significant role as a site of transmission during the early months of the pandemic.
Agricultural workers were deemed essential workers in Canada during the pandemic. According to government records, 32% of farm workers in Ontario worked in indoor greenhouses, where humidity and ventilation allowed for easier viral transmission. Moreover, one-third of farmworkers in Canada are temporary foreign workers who share transportation and close living quarters.
The analysis studied outbreaks with a start date from January 1 to December 31, 2020; all cases associated with these outbreaks up to January 31, 2021; and trends in outbreaks by season and type of farm, the authors of the report said. The outbreaks took place in the pre-vaccine period of the pandemic.
Almost 60% of outbreaks involved greenhouses
Of the 64 outbreaks included in this study, the median size was 14.5 cases (range, 1 to 240), and the median duration was 23 days (range, 0 to 128). Most case patients were male (83.2%), the median age was 35 years, and 10.0% had one or more comorbidities. Almost a third (31.2%) of patients were asymptomatic, 16 required hospitalization, and 3 died.
"A total of 37 (57.8%) farm outbreaks occurred on farms classified as greenhouses," the report stated. Farm-based outbreaks peaked in May 2020, slowed down during the summer months, and then spiked again in December.
"The indoor and crowded nature of greenhouse work, at a time when indoor masking was not routinely recommended or used, may have promoted the transmission of COVID-19 and could have contributed to outbreaks on farms even when there were lower levels of community transmission" the report concluded.
Source: cidrap.umn.edu