This is a summary, written by members of the CITF Secretariat, of

Santerre K, Thériault M, Brousseau N, Rochette S, Pelletier J-N, Gilbert C, Masson J-F, Baz M, Boudreau D, Trottier S. Cohort Profile: Prospective Cohort to Study the COVID-19 Immune Response in Retail Workers in Québec, Canada (CISACOV). medRxiv 2023.08.18.23294172; doi:

The results and/or conclusions contained in the research do not necessarily reflect the views of all CITF members.

A CITF-funded team studied the risk to grocery store, hardware store, bar, and restaurant workers during the COVID-19 pandemic. This cohort profile preprint article, not yet peer-reviewed, describes participant demographic, socioeconomic, behavioural, clinical, and occupational characteristics, as well as whether participants tested positive for SARS-CoV-2, experienced any COVID-19 symptoms (where applicable), and were vaccinated. The study was led by Dr. Sylvie Trottier in collaboration with Dr. Denis Boudreau (both from Université Laval).

People who work with the public are an understudied occupational group that may have been at increased risk of contracting SARS-CoV-2 during the COVID-19 pandemic. This longitudinal cohort of retail/food workers, which began in April 2021 and ended in October 2022, helps to better document the incidence of SARS-CoV-2 infection in this front-line group and their immune responses to infection and/or vaccination.

Key findings:

  • Participants were aged 18 to 75 and worked in grocery stores, hardware stores, bars, or restaurants within the Quebec City metropolitan area.
  • A total of 304 participants were recruited between April 20, 2021 and May 9, 2022. They were invited to attend three visits (each separated by ∼12 weeks), during which they provided blood samples and information on their characteristics, COVID-19 symptoms, and vaccination.
  • Between March 15th, 2022 and October 3rd, 2022, an extension phase of two additional visits was carried out to document the impact of the Omicron variant among the 198 participants who were still eligible for recruitment at or after the third visit.

The study covered seven pandemic waves, capturing data on confirmed infection with diverse variants and collecting nearly 1300 blood samples that will be used to study the immune response to SARS-CoV-2.