COVID-19 outbreak trends in Canada, 2021

Area of Science:

• Public Health
• Epidemiology
• Infectious Disease Surveillance

Background:

• The Public Health Agency of Canada established the Canadian COVID-19 Outbreak Surveillance System (CCOSS) in January 2021.
• CCOSS aimed to monitor the incidence and severity of COVID-19 outbreaks in diverse community settings.
• The system was designed to complement existing case surveillance efforts.

Purpose of the Study:

• To analyze COVID-19 outbreak trends, severity, and size across Canada in 2021.
• To understand the distribution of outbreaks in various community and congregate settings.
• To assess the utility of the CCOSS system in informing public health responses.

Main Methods:

• Descriptive analyses were conducted on weekly cumulative COVID-19 outbreak line lists submitted by seven Canadian provinces to CCOSS.
• Data spanned from January 3, 2021, to January 1, 2022.
• Analysis included outbreak settings, confirmed cases, hospitalizations, and deaths.

Main Results:

• Outbreak incidence generally mirrored case incidence trends.
• Schools (39%) and industrial/agricultural settings (21%) reported the most frequent outbreaks.
• Congregate living settings, specifically correctional facilities (median 18 cases) and long-term care facilities (median 10 cases), experienced the largest outbreaks.

Conclusions:

• COVID-19 outbreaks were most frequent in community settings like schools, but largest in congregate living settings.
• Outbreak surveillance data provided valuable insights complementing case incidence data.
• The CCOSS system enhanced the understanding of COVID-19 dynamics in Canada.