Update on COVID-19 in Canada: Epidemiology and Modelling - Canada.ca/coronavirus March 26th, 2021
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Update on COVID-19 in Canada: Epidemiology and Modelling March 26th, 2021 Canada.ca/coronavirus
National daily case counts and severity indictors are back on the rise
Number of cases/ Number of
Total hospitalizations deaths
On average over the past 7 days:
9,000 4,057 cases 900
8,000 2,194 hospitalizations 800
29 deaths
7,000 700
6,000 600
5,000 500
4,000 400
3,000 300
2,000 200
1,000 100
0 0
01Mar 01Apr 01May 01Jun 01Jul 01Aug 01Sep 01Oct 01Nov 01Dec 01Jan 01Feb 01Mar
Cases Hospitalizations Deaths
Data as of March 23, 2021
Note: 7-day moving averages. Total hospitalizations include all people in hospital on that day, and the average length of stay in hospital is 1
approximately two weeks.
Each new case in Canada is spreading infection to more than one
person, bringing the epidemic back into a growth pattern
2
Since early March,
1.5 When Rt is consistently >1, Canada’s Rt has been >1
the epidemic is growing
1
When Rt is consistently
COVID-19 incidence is increasing in provinces west of the Atlantic region
AB SK
40 BC 40 40
30
30 30
20
20 20
10
10 10
0 0 0
Number of 01Apr 01Jul 01Oct 01Jan 01Apr 01Jul 01Oct 01Jan 01Apr 01Jul 01Oct 01Jan
cases per
100,000
MB ON QC
population 40
40 40
30 30
30
20
20 20
10
10 10
0 0 0
01Apr 01Jul 01Oct 01Jan 01Apr 01Jul 01Oct 01Jan 01Apr 01Jul 01Oct 01Jan
Date of case report
Data as of March 23, 2021
3
COVID-19 hospitalization rates levelling off or increasing in provinces
with elevated disease activity
Number of cases in hospital
per 100,000 population
30
25
20
15
10
5
0
01 Apr 01 May 01 Jun 01 Jul 01 Aug 01 Sep 01 Oct 01 Nov 01 Dec 01 Jan 01 Feb 01 Mar
AB BC MB ON QC SK
Data as of March 22, 2021
Note: 7-day moving average 4
Highest incidence of COVID-19 occurring in Northern health regions of
British Columbia, Saskatchewan, Manitoba, and parts of Ontario
Cases per 100,000 population (Mar 7 – Mar 22, 2021)
400 +
37 of 99 health regions
201 - 400
with > 100 cases per
101 - 200
100,000 population
51 - 100
over a 14-day period
26 - 50
1 - 25
0
Data sources: COVID-19 Canada Open
Data Working Group. Epidemiological
data from the COVID-19 Outbreak in
Canada
Data as of March 22, 2021
Note: Map only shows COVID-19 cases where health region had been attributed in source data 5
Incidence rates have declined among older age groups and are now
highest among young adults aged 20 to 39 years
Number of reported cases Incomplete data,
per 100,000 population due to reporting lag
35
80+ years
30
25
20
15 20 to 39 years
10
20 to 39 years
5
80+ years
0
01 Jun 01 Jul 01 Aug 01 Sep 01 Oct 01 Nov 01 Dec 01 Jan 01 Feb 01 Mar
Date of illness onset*
0 to 19 20 to 39 40 to 59 60 to 79 80+
Data as of March 22, 2021
Note: 7-day moving average *The earliest of the following dates: Onset date, specimen collection date, laboratory testing date, date 6
reported to province or territory, or date reported to PHAC
Number and size of outbreaks in long term care* homes continue to
decline
Number of Outbreaks
500
450
400 Studies in QC, BC and ON
350 showed high vaccine
300 effectiveness and significant
reductions in symptomatic
250 illness1,2 and severe
200 outcomes3 among long-term
150 care home residents and
health care workers after
100
single dose of mRNA
50 vaccine.
0
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar**
2-4 cases 5-9 cases 10-24 cases 25-49 cases 50-99 cases 100+ cases
1INSPQ. https://www.inspq.qc.ca/sites/default/files/publications/3111-vaccine-effectiveness-strategy-
Data as of March 23, 2021; by date outbreak first reported vaccination-shortage-covid19.pdf
Note: *Including retirement residences. Data based on publicly 2BCCDC. http://www.bccdc.ca/about/news-stories/news-releases/2021/early-findings-show-the-first-
7
vaccine-dose-reduced-the-risk-of-covid-19-by-80-per-cent-or-more
reported information. **Data is incomplete for March, 2021 3Brown KA et al. https://doi.org/10.47326/ocsat.2021.02.13.1.0
Indigenous communities’ experience of COVID-19 has moved from
strength through challenge to resilience
Newly reported cases per
100,000 population Incomplete data,
600 due to reporting lag Territories and most Indigenous
First Nations on-reserve Canada communities
500 • were successful in efforts to
limit introduction and spread
400 early in the pandemic
300 • innovated rapidly to control
introduction and further
200
spread through fall and winter
100
• showed leadership in rolling
0 out vaccines early to protect
Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar high-risk populations
COVID-19 incidence in First Nations on-reserve and general
Canadian population
Data as of March 19, 2021
Note: By episode date 8
Vaccination coverage is increasing across Canada, with benefits being
seen in prioritized high-risk populations
Cumulative percent of the total
population (all ages) who have received
at least one dose of a COVID-19 vaccine • More than 4.5 million vaccine
doses have been administered
• More than 11% of Canadian adults
have received at least one dose of
vaccine
• Nearly 60% of seniors aged 80+
have received at least one dose of
vaccine
• In the three territories, more than
60% of adults have received at
least one dose
Data as of March 20, 2021
9Short-term forecast predicts total cases will increase faster than total
deaths due to the recent acceleration in daily cases
Cumulative cases predicted to April 4, 2021: Cumulative deaths predicted to April 4, 2021:
973,080 to 1,005,020 22,875 to 23,315
23,500
Cumulative number of deaths
1,000,000
Cumulative number of cases
23,250
975,000
23,000
950,000
22,750
925,000
900,000 22,500
875,000 22,250
850,000 22,000
10Mar 15Mar 20Mar 25Mar 30Mar 04Apr 10Mar 15Mar 20Mar 25Mar 30Mar 04Apr
Cumulatively reported cases in Canada by March 20, 2021 Cases added since March 20 when the prediction was made
Prediction to Apr. 4, 2021 Lower 95% prediction limit Upper 95% prediction limit
Data as of March 23, 2021.
Note: Extrapolation based on recent trends using a forecasting model (with ranges of uncertainty). 10Number and proportion of variant of concern cases are increasing
rapidly in several areas of Canada
% of cases that are
Number of VOC cases VOC*
Incomplete data,
1,000 25 due to reporting lag 100
900 90
20
800 80
700 15 70
600 10 60
500 50
5
400 40
300 0 30
18 Dec 01 Jan 15 Jan 29 Jan 12 Feb 26 Feb 12 Mar
200 20
100 10
0 0
18 Dec 01 Jan 15 Jan 29 Jan 12 Feb 26 Feb 12 Mar
B.1.1.7 Lineage not assigned B.1.351 P.1 % of all COVID-19 cases that are VOC*
Data as of March 24, 2021
Note: By laboratory specimen collection date. *Includes cases with confirmed VOC lineage and cases with a mutation associated with VOC. Cases with no assigned 11
lineage reported only by MB, ON, NB, and PEI, resulting in underestimation. QC and SK are excluded from this analysis.Longer-range forecast shows stronger public health measures will be
required to counter more transmissible variants of concern
12,000
With spread of
10,000 VOCs and we
maintain or
increase the
8,000 current number of
people we contact
Reported
6,000 each day
cases
4,000 If VOCs are
controlled by
reducing the
2,000 current number of
people we contact
0 each day
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr
Data as of March 24, 2021 The PHAC McMaster forecast is based on current estimates transmission rates fitted to reported cases. It assumes VOCs are introduced in mid-
Dec (~1 week prior to first detected case in Canada) at very low prevalence; VOCs (all VOCs known to date) are 50% more transmissible than
Note: Ensemble of output from PHAC-McMaster wild-type; growth rate AND replacement rate are negatively correlated with the strength of public health measures. Proportion of VOC is
12
obtained by a combination of calibrating to surveillance data as well as information on proportions of cases that are VOC. Recent changes in
and Simon Fraser University models testing rates are not taken into account in this forecast. SFU methods are at https://www.sfu.ca/magpie/blog/variant-simple-proactive.htmlInternational experience shows that stronger measures are needed to
control epidemic growth driven by more contagious variants of concern
Rate per 1,000,000 population
Data as of March 23, 2021
Note: 7-day moving average 13Data inform jurisdictions’ decisions to adjust restrictive public health
measures
Vaccine coverage and effectiveness (including for circulating VOCs) supports epidemic control and
enables improvement of other indicators
Sufficient public health Risk reduction
COVID-19 Sufficient healthcare measures are in
capacity is in place to test,
transmission, capacity exists, place for
trace, isolate and
including VOCs, is including substantial populations who
quarantine a high
controlled to clinical care capacity are at high risk
proportion of cases and
manageable levels to respond to surges and in high risk
contacts
settings
Note: Criteria and indicators build on those established by the Special Advisory Committee in July 2020 and published online here:
https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/canadas-reponse/recommendations-lifting- 14
restrictive-public-health-measures.htmlMany factors will influence the epidemiological situation and timing for
adjusting public health measures… but summer holds promise
Key factors include:
• Spread of variants of concern that impact transmission, severity of illness and vaccine effectiveness
• Degree to which public health measures and our adherence to them are successful in controlling
transmission while vaccines roll out
• Effect of vaccines in preventing transmission in addition to preventing severe disease and death
• How many people are vaccinated
15Success in vaccines versus variants depends on all of us!
Every moment we realise we could be
• Updated forecasts, with variants of concern spreading, doing more, better...
show we must continue with strong measures until
enough people are vaccinated to safely ease restrictions.
• Acceleration of vaccination programs will bring more
benefits, protecting more Canadians and helping us resume Is an opportunity we can take to do our
our valued social and economic activities. best to protect each other...
• We are closer now than ever, but it is still too soon to
relax measures and too soon to gather in areas where
COVID-19 is circulating.
• As Passover, Easter, and Ramadan approach, make
plans to celebrate safely, including having virtual
celebrations to protect and support each other as we make
fewest interactions, with the fewest people for
this last big push to keep the path clear for vaccines!
the shortest time at the greatest distance
possible while wearing the best-fitting mask
16ANNEX
17Longer-range forecasts show strong resurgence nationally if variants of
concern replace wild type virus and public health measures remain at
current levels
With spread of VOCs and we
maintain or increase the
current number of people we
contact each day
Reported
cases If VOCs do not spread or are
controlled by reducing the
current number of people we
contact each day
Data as of March 24, 2021 The PHAC McMaster forecast is based on current estimates transmission rates fitted to reported cases. It assumes VOCs are introduced in mid-
Dec (~1 week prior to first detected case in Canada) at very low prevalence; VOCs (all VOCs known to date) are 50% more transmissible than
Note: Ensemble of output from PHAC-McMaster wild-type; growth rate AND replacement rate are negatively correlated with the strength of public health measures. Proportion of VOC is
obtained by a combination of calibrating to surveillance data as well as information on proportions of cases that are VOC. Recent changes in
18
and Simon Fraser University models testing rates are not taken into account in this forecast. SFU methods are at https://www.sfu.ca/magpie/blog/variant-simple-proactive.htmlLong-range forecasting model assumptions
• The forecast combines estimates from two compartmental models reflecting the biology of COVID-19 and public health
response. One of the models was developed by PHAC in collaboration with McMaster University, and the other was
developed at Simon Fraser University.
• The ensemble forecast assumes VOCs are 40-50% more transmissible compared to previous strains. This value is used
to estimate the rate at which VOCs replace existing strains.
• VOCs are considered to have been introduced at very low prevalence a week prior to the first reported case in each
province. The proportion of cases due to VOCs over time in each jurisdiction is then adjusted to match provincial VOC
screening/surveillance data.
• Changes to public health measures impact the speed with which VOCs replace previous strains; stronger public health
measures result in slower growth and replacement rates. The impact of public health measures on controlling pre-existing
strains and variants is obtained by fitting the model to surveillance data while accounting for the estimated prevalence of
variant cases.
• The ensemble forecast includes a graph showing expected increases in cases with VOC spread (grey line), and a graph
which assumes that transmission (including VOCs) is controlled (purple line) by public health measures that are equivalent
to a 20-30% reduction in rates of contact between people in Canada
• Forecasts are limited to mid-April. This is because assumptions related vaccination roll-out are not incorporated in the
model for the below reasons:
• Only a small proportion of the Canadian public have been vaccinated
• At present there is uncertainty about the degree to which vaccines protect against infection and transmission
• The current target groups for vaccination (particularly older adults) contribute little to transmission.
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