update on covid-19 in canada: epidemiology and modelling
TRANSCRIPT
Canada.ca/coronavirus
Update on COVID-19 in Canada: Epidemiology and ModellingMarch 26th, 2021
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National daily case counts and severity indictors are back on the rise
Data as of March 23, 2021Note: 7-day moving averages. Total hospitalizations include all people in hospital on that day, and the average length of stay in hospital is approximately two weeks.
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Cases Hospitalizations Deaths
Number of cases/Total hospitalizations
Number of deathsOn average over the past 7 days:
4,057 cases 2,194 hospitalizations 29 deaths
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Each new case in Canada is spreading infection to more than one person, bringing the epidemic back into a growth pattern
Data as of March 23, 2021 Note: Calculations are based on the earliest date available for cases
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2020 2021Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar
When Rt is consistently <1, the epidemic is being brought under control
When Rt is consistently >1, the epidemic is growing
Since early March, Canada’s Rt has been >1
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Date of case report
Data as of March 23, 2021
Number of cases per 100,000
population
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010203040
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BC
010203040
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MB
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ON
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QC
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COVID-19 incidence is increasing in provinces west of the Atlantic region
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COVID-19 hospitalization rates levelling off or increasing in provinces with elevated disease activity
Data as of March 22, 2021Note: 7-day moving average
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AB BC MB ON QC SK
Number of cases in hospital per 100,000 population
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Highest incidence of COVID-19 occurring in Northern health regions of British Columbia, Saskatchewan, Manitoba, and parts of Ontario
37 of 99 health regions with > 100 cases per 100,000 population over a 14-day period
Data as of March 22, 2021Note: Map only shows COVID-19 cases where health region had been attributed in source data
400 +201 - 400101 - 20051 - 10026 - 501 - 25
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Data sources: COVID-19 Canada Open Data Working Group. Epidemiological data from the COVID-19 Outbreak in Canada
Cases per 100,000 population (Mar 7 – Mar 22, 2021)
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20 to 39 years
20 to 39 years
80+ years
80+ years
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01 Jun 01 Jul 01 Aug 01 Sep 01 Oct 01 Nov 01 Dec 01 Jan 01 Feb 01 MarDate of illness onset*
0 to 19 20 to 39 40 to 59 60 to 79 80+
Number of reported cases per 100,000 population
Incidence rates have declined among older age groups and are now highest among young adults aged 20 to 39 years
Data as of March 22, 2021Note: 7-day moving average *The earliest of the following dates: Onset date, specimen collection date, laboratory testing date, date reported to province or territory, or date reported to PHAC
Incomplete data, due to reporting lag
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Number and size of outbreaks in long term care* homes continue to decline
Data as of March 23, 2021; by date outbreak first reportedNote: *Including retirement residences. Data based on publicly reported information. **Data is incomplete for March, 2021
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Number of Outbreaks
2-4 cases 5-9 cases 10-24 cases 25-49 cases 50-99 cases 100+ cases
Studies in QC, BC and ON showed high vaccine effectiveness and significant reductions in symptomatic illness1,2 and severe outcomes3 among long-term care home residents and health care workers after single dose of mRNA vaccine.
1INSPQ. https://www.inspq.qc.ca/sites/default/files/publications/3111-vaccine-effectiveness-strategy-vaccination-shortage-covid19.pdf 2BCCDC. http://www.bccdc.ca/about/news-stories/news-releases/2021/early-findings-show-the-first-vaccine-dose-reduced-the-risk-of-covid-19-by-80-per-cent-or-more 3Brown KA et al. https://doi.org/10.47326/ocsat.2021.02.13.1.0
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COVID-19 incidence in First Nations on-reserve and general Canadian population
First Nations on-reserve Canada
Indigenous communities’ experience of COVID-19 has moved from strength through challenge to resilience
Data as of March 19, 2021Note: By episode date
Mar Apr May Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar
Incomplete data, due to reporting lag Territories and most Indigenous
communities • were successful in efforts to
limit introduction and spread early in the pandemic
• innovated rapidly to control introduction and further spread through fall and winter
• showed leadership in rolling out vaccines early to protect high-risk populations
Newly reported cases per 100,000 population
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Vaccination coverage is increasing across Canada, with benefits being seen in prioritized high-risk populations
• 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
Cumulative percent of the total population (all ages) who have received at least one dose of a COVID-19 vaccine
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Cumulative cases predicted to April 4, 2021: 973,080 to 1,005,020
Cumulative deaths predicted to April 4, 2021: 22,875 to 23,315
Short-term forecast predicts total cases will increase faster than total deaths due to the recent acceleration in daily cases
Data as of March 23, 2021.Note: Extrapolation based on recent trends using a forecasting model (with ranges of uncertainty).
10Mar 15Mar 20Mar 25Mar 30Mar 04Apr
1,000,000
975,000
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Cumulatively reported cases in Canada by March 20, 2021Prediction to Apr. 4, 2021 Lower 95% prediction limit Upper 95% prediction limit
Cases added since March 20 when the prediction was made
10Mar 15Mar 20Mar 25Mar 30Mar 04Apr
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Number and proportion of variant of concern cases are increasingrapidly in several areas of Canada
Data as of March 24, 2021Note: By laboratory specimen collection date. *Includes cases with confirmed VOC lineage and cases with a mutation associated with VOC. Cases with no assigned lineage reported only by MB, ON, NB, and PEI, resulting in underestimation. QC and SK are excluded from this analysis.
0102030405060708090100
0100200300400500600700800900
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18 Dec 01 Jan 15 Jan 29 Jan 12 Feb 26 Feb 12 Mar
% of cases that are VOC*Number of VOC cases
B.1.1.7 Lineage not assigned B.1.351 P.1 % of all COVID-19 cases that are VOC*
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Incomplete data,due to reporting lag
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Longer-range forecast shows stronger public health measures will be required to counter more transmissible variants of concern
Data as of March 24, 2021Note: Ensemble of output from PHAC-McMaster and Simon Fraser University models
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 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 testing rates are not taken into account in this forecast. SFU methods are at https://www.sfu.ca/magpie/blog/variant-simple-proactive.html
If VOCs are controlled by reducing the current number of people we contact each day
With spread of VOCs and we maintain or increase the current number of people we contact each day
Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr
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Reported cases
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International 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, 2021Note: 7-day moving average
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Data inform jurisdictions’ decisions to adjust restrictive public health measures
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-restrictive-public-health-measures.html
COVID-19 transmission, including VOCs, is controlled to manageable levels
Sufficient public health capacity is in place to test, trace, isolate and quarantine a high proportion of cases and contacts
Sufficient healthcare capacity exists, including substantial clinical care capacity to respond to surges
Risk reduction measures are in place for populations who are at high risk and in high risk settings
Vaccine coverage and effectiveness (including for circulating VOCs) supports epidemic control and enables improvement of other indicators
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Many 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
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Success in vaccines versus variants depends on all of us!
• Updated forecasts, with variants of concern spreading, 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 our valued social and economic activities.
• 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 this last big push to keep the path clear for vaccines!
Every moment we realise we could be doing more, better...
Is an opportunity we can take to do our best to protect each other...
fewest interactions, with the fewest people for the shortest time at the greatest distance
possible while wearing the best-fitting mask
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ANNEX
18Data as of March 24, 2021Note: Ensemble of output from PHAC-McMaster and Simon Fraser University models
Longer-range forecasts show strong resurgence nationally if variants of concern replace wild type virus and public health measures remain at current levels
If VOCs do not spread or are controlled by reducing the current number of people we contact each day
With spread of VOCs and we maintain or increase the current number of people we contact each day
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 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 testing rates are not taken into account in this forecast. SFU methods are at https://www.sfu.ca/magpie/blog/variant-simple-proactive.html
Reported cases
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Long-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.