Table 4. Coronavirus disease 2019-positive mink farmworkers in British Columbia, January 14 to October 31, 2021.

Date range	N	%	Context
January 14 to March 17, 2021	2a	16.6	Before vaccination being offered to farmworkers
March 18 to May 31, 2021	5	41.6	After offering vaccination (mandatory vaccination not in place until April 15, 2021): n=1 had chosen not to be vaccinated n=1 was positive within 14 days of vaccination with first dose (not considered partially immunized) n=3 were positive more than 14 days after receipt of a first dose of vaccine (considered partially immunized)
June 1 to October 31, 2021	5	41.6	Following receipt of 2 doses of vaccine: n=5 were considered fully vaccinated and part of the outbreak on Farm 3
Total	12	100.0	Human cases arose on 3 of 6 remaining farm unitsb from the start of the surveillance system until the end of the study period

^a One worker was detected through community testing following household exposure rather than through the worker surveillance system

^b Of the original nine active mink farms in British Columbia, two pairs of farms were submitting human surveillance samples jointly as they had integrated operations and were in close proximity to each other with workers working on both sites. It was not possible to separate these farms through the human surveillance system. From these original seven independent farm units, one farm (Farm 2) had ceased operation, culling all of its mink after an outbreak was detected in the mink herd, resulting in six remaining farm units by January 2021