COVID-19 epidemiology update: Summary :

COVID-19 activity levels are based on data from provincial and territorial (PT) partners. National COVID-19 activity levels were developed with PT partners to monitor COVID-19 activity at the national and PT levels using a standard set of core indicators. Based on these indicators, COVID-19 activity can range from level 0 (no activity) to level 4 (high activity). They are presented with the overall change (increase, decrease, no change) from the previous week.

Indicators : The overall COVID-19 activity level is assessed based on the following three indicators, where available:

1. Weekly percent positivity
   • Weekly number of lab positive tests / Weekly total number of tests x 100.
   • Note: This indicator is only incorporated into overall assessment if the testing rate is greater than or equal to 100 tests per 100,000 population per week. This indicator is used to provide information about overall activity level and trajectory.
2. Weekly long term care facility (LTCF) outbreaks per 1,000,000 population
   • Weekly number of LTCF outbreaks / Total population in jurisdiction x 1,000,000.
   • Note: This indicator is used to provide information on overall activity level and trajectory.
3. Weekly COVID-19 wastewater trajectory
   • Trajectory of weekly COVID-19 wastewater viral levels compared to the previous week.
   • Note: This indicator is used to provide information on overall trajectory only.

Assessment process : The overall COVID-19 activity level is assessed based on the following three indicators, where available:

• Each indicator is assigned a level ranging from ‘no activity detected’ (level 0) to ‘very high activity’ (level 4), based on established thresholds (increasing, decreasing, or no change) of a change of 10% or more compared to the previous week.
• Overall activity level is then determined using the average level of the available indicators (rounding to the nearest whole number).
• Overall trajectory, or the direction of change (based on 10% change compared to the previous week), is calculated based on the mode of the trajectories from available indicators.

Data assessment caveats : The overall COVID-19 activity level is assessed based on the following three indicators, where available:

• This information is based on data from PT partners. For more up to date information and for public health recommendations or risk assessments, please refer to PT websites.
• Weekly changes in tests performed, and LTCF outbreaks reflect changes in counts between the end of the latest epidemiological week and the end of the previous epidemiological week. Data are updated on an ongoing basis and are subject to change.
• PT testing practices, data sources and reporting to PHAC vary across jurisdictions.
• There may be variations in the COVID-19 activity across a jurisdiction. It’s possible that if there are outbreaks occurring in one area, it may result in a higher level of COVID-19 activity. Weekly activity level assessments are intended to provide a high-level overview of COVID-19 spread using standard indicators at the national and PT level. They may not reflect the true extent of geographic spread of COVID-19.