Provincial Respiratory Surveillance Report

COVID-19 Technical Notes


Public Health Information Management System (PHIMS)

PHIMS is a secure, integrated electronic public health record designed to assist public health practitioners in Manitoba with management of:

  • communicable disease cases and contacts
  • outbreaks
  • immunizations
  • vaccine inventory

PHIMS provides authorized health-care professionals in Manitoba with the ability to collect, share and analyze a wide range of health information at the regional and provincial levels. Data from PHIMS are used in a range of public reports.

The PHIMS database is refreshed daily at 1:00am.

Surveillance Case Definition

Cases include both confirmed and probable cases. Surveillance case definitions are provided for the purpose of standardizing case classification and reporting. They are based on evidence, public health response goals, and are subject to change as new information becomes available. Please visit https://manitoba.ca/asset_library/en/coronavirus/interim_guidance.pdf for the most current case definition.

Probable case – A person who:

  • has a fever (>38°C), AND/OR
  • has new onset of (or exacerbation of chronic) cough or difficulty breathing, AND
  • meets exposure criteria, AND
  • for whom laboratory diagnosis of COVID-19 is:
    • inconclusive (inconclusive is defined as a positive test on a single real-time PCR target or a positive test with an assay that has limited performance data available),
      • NAATs must be validated for detection of the virus that causes COVID-19.
      • An indeterminate result on a real-time PCR assay is defined as a late amplification signal in a real-time PCR reaction at a predetermined high cycle threshold value. This may be due to low viral target quantity in the clinical specimen approaching the limit of detection of the assay, or may represent nonspecific reactivity (false signal) in the specimen. When clinically relevant, indeterminate samples should be investigated further in the laboratory (e.g. by testing for an alternate gene target using a validated real-time PCR or nucleic acid sequencing that is equally or more sensitive than the initial assay or method used) or by collection and testing of another sample from the patient with initial indeterminate result.
  • A (un-tested) person with:
    • Fever (over 38 degrees Celsius), AND/OR
    • Cough (new or exacerbated chronic); AND
    • Close contact with a confirmed case of COVID-19, OR
    • Lived in or worked in a closed facility known to be experiencing an outbreak of COVID-19 (e.g., long-term care facility, correctional facility)

Confirmed case – A person with a laboratory confirmation of infection with the virus that causes COVID-19 performed at a community, hospital or reference laboratory (NML or a provincial public health laboratory) running a validated assay. This consists of detection of at least one specific gene target by a NAAT assay (e.g. real-time PCR or nucleic acid sequencing).

Close contact – A person who provided care for the patient, including healthcare workers, family members or other caregivers, or who had other similar close physical contact or who lived with or otherwise had close prolonged contact with a probable or confirmed case while the case was ill.

Variants of Concern (VOC)

Viruses like the ones that cause COVID-19 are constantly changing through mutation. New variants occur over time; sometimes the new variants emerge and disappear while others last. It is not unexpected to see cases of COVID-19 linked to VOCs in Manitoba. Current VOCs identified globally include:

  • B.1.1.7 (Alpha): first identified in the United Kingdom (UK)
  • B.1.351 (Beta): first identified in South Africa
  • P.1 (Gamma): first identified in Brazil
  • B.1.617, B.1.617.1 (Kappa), B.1.617.2 (Delta), B.1.617.3: first identified in India
  • Public health officials continue to actively monitor and study emerging COVID-19 VOCs given their potential to:
  • Spread more quickly in the population compared to the current strain.
  • Cause more severe disease.
  • Compromise natural or vaccine induced immunity.
    • VOCs can be more difficult to control, and often require stronger or additional public health measures.
    • Information is rapidly evolving on the VOCs and their effects in Manitoba.

Please visit https://manitoba.ca/asset_library/en/coronavirus/interim_guidance.pdf for more information.

Cumulative Data

Cumulative data includes updates to previous weeks; due to reporting delays or amendments, the sum of weekly report totals may not add up to cumulative totals.

Specimen Collection Date

The date the laboratory specimen was collected is used to assign cases to the epidemiological week in this report. Occasionally, if the specimen collection date is not available, the laboratory report date is used. If both dates are not available, the earliest date a case was reported to Public Health is be used.

Epidemiological Week

Time trends in this report are presented by epidemiological week, a schedule used by the national FluWatch program coordinated by Public Health Agency of Canada.

Incidence Rate

Incidence rate measures the frequency that COVID-19 occurs in a population. It is calculated as the total number of new cases multiplied by 100,000 and divided by the total count in a population based on the provincial mid-year population file in 2019.

Influenza-Like-Illness (ILI) in General Population

ILI is defined as acute onset of respiratory illness with fever and cough and with one or more of the following - sore throat, arthralgia, myalgia, or prostration.

COVID-19 Associated Severe Outcome

Hospitalizations and ICU submissions in COVID-19 cases are extracted from the provincial data system, Admission, Discharge and Transmission. Due to a need for timely reporting, hospitalizations and ICU submissions do not need to be directly attributed to COVID-19. Instead an association to a positive COVID-19 laboratory result is sufficient. Duplicate submissions for the same patient within the same illness episode are excluded. In this report, only Manitoba residents are included. ICU admissions are also included in hospitalizations.

From March 15, 2022: COVID-19 associated deaths

COVID-19 associated deaths are defined as all laboratory-confirmed COVID-19 cases who have died 30 days after the earliest specimen collection date in the most recent investigation; or where COVID-19 infection was diagnosed post-mortem. Note that the reason for death does not have to be attributable to COVID-19. A positive laboratory test is sufficient for reporting.

Prior to March 15, 2022: Deaths due to COVID-19

Source: Adapted from WHO International Guidelines for Certification and Classification (coding) of COVID-19 as a cause of death

A death resulting from a clinically compatible illness, unless there is a clear alternative cause of death that cannot be related to COVID disease (e.g. trauma). There should be no period of complete recovery* from COVID-19 between illness and death.

*Recovery in this context means no residual effects or complications from COVID-19, and does not refer to the status of "recovered", which refers to clients who are off isolation or precautions and are no longer considered infectious

Testing

Provincial data about COVID-19 related tests are collected daily from Cadham Provincial Laboratory, Shared Health, and Dynacare.

National testing data are collected daily from the national Coronavirus disease (COVID-19) Outbreak update webpage.

Outbreak

Outbreaks are reported to the Epidemiology and Surveillance (E&S) unit via phone call or email from regional public health staff, or by Cadham Provincial Laboratory (CPL) advising the assignment of an outbreak code. CPL submits both positive and negative laboratory results related to outbreaks to E&S. Details related to outbreak investigations are reported from Regional Health Authorities (RHAs) to E&S by completing an outbreak summary report.

COVID-19 Outbreak

In the context of the COVID-19 pandemic, two or more cases of COVID-19 diagnosed within a 14-day period in a setting, with evidence of transmission occurring within the setting defines an outbreak. In a highly vulnerable setting, a single laboratory-confirmed case of COVID-19 in a staff member, volunteer, or resident may define an outbreak at the discretion of the Medical Officer of Health.

Respiratory Outbreak
  • Schools: Greater than 10% absenteeism or absenteeism that is higher (e.g. >5-10%) than the expected level as determined by the school or public health authority, and is likely due to ILI.
  • Hospitals and residential institutions: two or more cases of ILI within a seven-day period.
  • Other settings: two or more cases of ILI within a seven-day period, including at least one laboratory confirmed case; i.e. workplace, closed communities.

FluWatch

FluWatch is an important part of Canada's national influenza surveillance program. It relies on an online health surveillance system that helps track the spread of influenza and influenza-like illness in the community across Canada. FluWatchers are volunteers from all over Canada. Each week, FluWatchers get an e-mail asking if they had a cough or fever in the previous week. Additional questions may be asked if participants reported ILI symptoms. Answers are anonymous.

Manitoba data are included in this report.

FluWatch typically tracks information related to influenza, but due to the COVID-19 pandemic, the focus is shifting to tracking COVID-19 over the spring and summer months.

More volunteers are needed across Canada to help track the spread of influenza and COVID-19. Please consider signing up to be a FluWatcher.

ILI Visits to Sentinel Physicians

Manitoba participates in FluWatch, Canada's national surveillance system coordinated by the Public Health Agency of Canada (PHAC), which monitors the spread of influenza and ILI on a year-round basis. FluWatch consists of a network of laboratories, hospitals, physician clinics and provincial and territorial ministries of health. In 2019-2020, there were 19 sentinel physicians recruited throughout Manitoba reporting to FluWatch weekly. The Epidemiology and Surveillance Unit receives weekly reports from FluWatch, which describe the ILI rate for Manitoba and for each participating sentinel physician. The reporting sentinel physicians vary by week, and their reports may not be representative of ILI activity across the province.

Respiratory Visits to Emergency Department

Daily statistics of visits to Emergency Departments (ED) in the Winnipeg Regional Health Authority (WRHA) including all visits and those related to respiratory illness are submitted to the Epidemiology and Surveillance Unit weekly. Respiratory visits are defined as patients whose triage chief complaints contain one or more of these symptoms: weakness, shortness of breath, cough, headache, fever, cardiac/respiratory arrest, sore throat, and upper respiratory tract infection complaints.

Exposure

Exposure to COVID-19, indicated by acquisition events (how someone acquired the infection within 14 days prior to symptom onset) and transmission events (where a case may have transmitted the infection to others from 48 hours prior to symptom onset until the case is no longer infectious), is assessed to determine the most likely source of infection in cases and contacts. Acquisition and transmission event details are retrieved from public health follow-up investigation reports of both cases and contacts and entered into PHIMS. In certain scenarios, determining the source of infection is straightforward and obvious. For example, categories like Travel and Close Contact to Known Cases are easier to determine. However, there are times when more information is required to finalize a category and then “pending” is used, or a category can simply not be identified. In those cases, the category “unknown” is applied. This is also a way to describe Community Acquired cases.

To better understand Community Acquired cases, we can look at the places that people were during both their periods of acquisition and transmission. This allows us to trend data more effectively but should not be considered as the source of infection or transmission.

We base our categories on those provided by the Public Health Agency of Canada, with the short description of each below.

Exposure Settings/Locations
  • Acute care setting, e.g. patient or staff in a hospital, urgent care, emergency room
  • Agricultural setting, e.g. animal processing plant, farm, veterinary clinic, other agricultural settings
  • Community healthcare setting, e.g. doctor’s office, laboratories, community clinics, support centres for people living with disabilities, COVID-19 testing centres, addiction/detox clinics, dental offices, chiropractor office
  • Congregate/communal living setting, e.g. dormitory, group home, military base, rooming house/residential hotel, shelter, short term residential facility, alternative isolation accommodations
    • For clusters only: condominium/apartments – resident, staff, or visitor
  • Correctional facility, e.g. provincial or federal correctional facility
  • Daycare or day home, staff, visitor, or student
  • Emergency services, e.g. paramedic, fire, police services
  • Food processing facility, e.g. food processing, seafood processing, beverage processing, aquaculture
  • Household (case residence), being exposed to those living in the same household/residence; visitors to case residence should not be included in this category.
  • Food services establishments, e.g. bar/tavern, cafeteria, mobile canteen, restaurant, nightclub, pastry/bakery shop, farm – direct to consumer (farmer’s market, farm to table), vending machines, other food services establishments, café shops
  • Industrial setting, e.g. warehouse, mining, oil sands work site, construction site – staff or visitor
  • Long term care facility, e.g. staff or visitor in personal care home, rehabilitation and long term care facility, palliative care units
  • Mass gathering event, e.g. conference, large sporting events, funeral, weddings
  • Office settings
  • Personal care setting, e.g. spa, barber, hair salon, massage salon, nail salon, beauty salon
  • Place of worship, e.g. church, synagogue, mosque
  • Public facilities, e.g. bathhouse, convention centre, park, swimming pool/water park, splash pad/wading pool, campground, forested area, river/lake/ocean
  • Recreational facility, e.g. fitness centre, community centre/arena, gym, museum, gallery, ice rinks, bingo halls, bowling alleys, casinos
  • Retail, e.g. grocery/retail store, shopping centre/retail, truck stop/gas station – staff or customer
  • Retirement residence, e.g. assisted living/seniors independent housing, retirement residence, assisted living/seniors independent housing, respite homes
  • Small, remote, and isolated communities (for cluster only), e.g. small, remote and isolated communities in Prairie Mountain Health Authority, Southern Health - Santé Sud Regional Health Authority, Interlake-Eastern Regional Health Authority, and Northern Health Region (not including Indigenous communities)
  • School, e.g. college/university, preschool, primary/secondary school, school - staff, student, or visitor
  • Social gathering, e.g. visiting friends and family, house party, private function, social network, birthday parties, family/friend gatherings
  • Travel/tourism, e.g. hotel/motel, vacation resort, travel outside of Canada/United States, travel within Canada, travel within home province/territory, travel within the United States, other travel settings, airport
  • Transportation, e.g. municipal transport system, commercial taxis, medical taxis/van, handi-transit, carpooling, car ride, school bus – staff or client
  • Workplace, any workplace setting attended by cases

Public Health Orders


  • PH order #1: Effective January 23, 2021: rule of 2 (i.e., two designated people (family or friends) to visit a household), outdoor visits up to 5 people, funerals up to 10 people, retail 25% capacity or 250 people, barbershops/hairstylists 25% capacity, non-regulated health services with restrictions, and separate orders for Northern Manitoba.

  • PH order #2: Effective March 5, 2021: continue rule of 2, designate a 2nd household to visit, gathering 10 people, places of worship 25% or 100 people, open any types of business with the exception of some recreational settings, retail stores & personal services increase capacity 50% or 250 people, restaurants and licensed premises increase capacity 50%, recreation and fitness 25% capacity.

  • PH order #3: Effective March 26, 2021: continue rule of 2, designate a 2nd household to visit, gathering 10 people outside private residence, outdoor public places now up to 25 people, any type of business to open except indoor theatres, indoor concert hall, casinos, and gaming centres, retail 50% capacity or 500 people, malls and person services 50% capacity, professional theatre groups, dance companies, symphonies and operas may hold rehearsals not accessible to public, restaurant & licensed premises tables of 6 from household indoors, and non-household outdoors, day camps for children 25%, weddings & funerals up to 25 people, drive in events people can leave vehicles.

  • PH order #4: Effective April 19, 2021: - continue rule of 2, gathering decreased to max 10 people outdoor and max 5 people indoor, malls/retails max 33% or 333 people, foot courts in malls max 50% sitting capacity, restaurant & licensed premises tables to continue with max 6 from household indoors & closed between 10:00pm -6:00am, weddings & funerals decreased to max 10 people, post-secondary schools max 50% or max 25 in a classroom capacity, day camps/cultural events for children 25%, sporting activities/recreations/community centers max 25% indoor and max 50% in dressing rooms, place of worships max 25% or 50 people.

  • PH order #5: Effective April 28, 2021: No visitors to private household, gathering decreased to max 10 people public outdoor and no indoor gathering, foot courts in malls closure, restaurant & licensed premises patio tables max 4 with no household restriction, gym and fitness centers max 25% and one caregiver per participant, outdoor sports one caregiver per participant, personal services max 50%, day camps 10 kids indoors&outdoors, retail&malls max 25% or 250 patrons (whichever is lower), place of worships max 25% or 10 people.

  • PH order #6: Effective May 9, 2021: Gatherings including multiple households decreased to max 5 people in public outdoor settings and no indoor gathering, no indoor religious, community or cultural gatherings. Personal services, casinos, VLTs, museums, galleries, libraries, gyms, fitness centers and day camps must close. Restaurants, bars and patios must close to in-person dining (take-out and delivery still allowed). Indoor sports, including after-school activities, dance, theatre and music schools must close. Outdoor sports and recreation activities are allowed with max 5 people, organized team games are not permitted. Retail stores, malls, markets and garden centres reduced to 10% capacity to a max of 100 people. Effective May 12, 2021: All K-12 schools in Winnipeg and Brandon must close and move to remote learning.

  • PH order #7: Effective May 22, 2021: No outdoor gathering with anyone outside a household on public or private property. This includes all recreational spaces including playgrounds, golf courses, parks and sports fields. Only one person per household is permitted to enter a business, with limited exceptions.

  • PH order #8: Effective May 29, 2021: Requirements for employees to work from home as much as possible. Increased requirements for malls to manage capacity and ensure compliance with shopping.

  • PH order #9: Effective June 12, 2021: Gatherings on private property/residence: indoors household only, and outdoors up to 5 people from no more than two other households, in addition to those who reside there. Gatherings on outdoor public spaces up to 5 people.

  • PH order #10: Effective June 26, 2021: outdoor gathering sizes on private property to double to 10 persons, and to allow outdoor visitors to briefly access homes for essential activities (e.g. to use a washroom); public outdoor gathering sizes to increase to 25 persons; retail businesses to open with increased capacity at 25 per cent to a limit of 250 persons, with no restrictions on the number of household members permitted to shop together; personal service businesses (hair and nail salons, estheticians, barbers, etc.) to reopen at 50 per cent capacity, on an appointment basis only; restaurants and bars to reopen at 25 per cent capacity for indoors and 50 per cent for outdoor dining. For indoor dining, patrons seated together must be from the same household unless all patrons at the table are fully immunized. Patrons who are fully immunized and from different households may dine together. For outdoor dining, tables are limited to a maximum of 8 patrons and can be from different households regardless of immunization status; indoor faith-based services and organized community gatherings (e.g. pow wows, sun dance ceremonies) to resume at 25 per cent capacity to a limit of 25 persons with masks worn at all times; outdoor faith-based and organized community gatherings (e.g. pow wows, sun dance ceremonies) to resume for up to 50 persons, provided distance can be maintained between households. Drive-in services continue to be permitted; outdoor weddings and funerals may take place with up to 25 participants, in addition to photographer and officiants. Indoor weddings and funerals remain limited to 10 persons; indoor dance, music, theatre and other organized sports and recreation activities may reopen at 25 per cent capacity to a limit of five persons, with no tournaments allowed; outdoor dance, music and theatre classes and other organized recreation activities may reopen for groups up to 25 people, with no tournaments allowed; swimming and wading pools, both indoor and outdoor, may reopen at 25 per cent capacity; gyms and fitness facilities may reopen for individual and group fitness classes at 25 per cent capacity with three meters distance maintained between patrons; and; summer day camps may reopen to a maximum of 20 participants in groups.

  • PH order #11: Effective July 17, 2021: indoor gatherings at private residences are permitted to a maximum of 5 people, plus the household members; indoor gatherings in public spaces are permitted to a maximum of 25 people; outdoor gatherings on private property increase to a maximum of 25 people; public outdoor gatherings increase to a maximum of 150 people; retail businesses increase to 50 per cent capacity or 500 people, whichever is lower; restaurants, licensed premises and food court capacities expand to 50 per cent capacity: outdoor maximum table size remains at 8 people; patrons may only sit together indoors if they are from the same household or if all patrons 12 years of age or older are fully immunized (unvaccinated children under 12 may dine with fully vaccinated members of their household in this case); opening hours extend to midnight; the requirement to purchase food when ordering alcohol no longer applies; VLTs may be operate with all other restaurant/bar rules applying (two-metre distance, only households or fully vaccinated people seated together); personal services (haircuts and styling, nail salons, estheticians and massage) continue at 50 per cent capacity; however, appointments are no longer required; dance, theatre, and music school capacities increase to 50 per cent capacity to a maximum of 25 people per group; indoor sporting facilities may host groups up to a maximum of 25 people, interaction between groups and tournaments are not permitted; day camp capacity increases to groups of 25, joint activities between groups and overnight camps are prohibited; outdoor recreation including games and practices may take place to maximum group size of 50 people; spectators are permitted and do not count towards this capacity limit; tournaments are not permitted; gym and fitness centre capacities expand to 50 per cent capacity; masks and increased physical distancing (three metres) are still required; outdoor weddings and funerals may include up to 150 participants in addition to photographers and officiants; indoor weddings or funerals increase to 25 people in addition to photographers and officiants; libraries may open to 50 per cent capacity to a maximum of 150 people, whichever is lower; faith-based and cultural gatherings (pow wows, sun dances) may expand to 50 per cent capacity or 150 people indoors, whichever is lower; masks and physical distancing between households is still required; if the facility design allows, the capacity limits may be applied to different physical spaces within the venue; outdoor faith-based and cultural gatherings permitted up to 150 people and drive-in services continue to be permitted without restriction; the following may now reopen for fully immunized people only, to a maximum capacity of 50 per cent: movie theatres; bingo halls, VLT lounges and casinos, and museums and galleries; museums operate under the fully vaccinated requirement when open to the public as a museum, both indoors and out, and if the museum is used as a private venue for another purpose (e.g. wedding), then the appropriate orders apply; unvaccinated children under 12 may attend/visit these facilities/events (as appropriate) if accompanied by fully vaccinated members of their household; large-scale, outdoor professional.

  • PH order #12: Effective August 7, 2021: allow the following sectors to open without restrictions: indoor and outdoor gatherings at private residences; gyms and fitness centres; libraries; personal services such as hair and nail salons; day camps; and retail businesses, markets, garden centres and malls. Other sectors will open with limited restrictions including: expanded capacity limits will remain in place for weddings, funerals and other public gatherings both indoors and outdoors including larger capacity limits for worship and cultural events like pow wows; restaurants and bars will no longer need to restrict the size or space between tables and dining will not be restricted to households or vaccinated individuals; however, patrons will still be expected to avoid congregating or socializing between tables; museums, galleries and movie theatres will remain limited to 50 per cent capacity but will no longer be restricted to vaccinated individuals; casinos and bingo halls, professional sporting events, horse and auto racing, and concert halls will continue to be limited to vaccinated individuals; however, all these facilities may now open to 100 per cent capacity; indoor and outdoor sports and recreation will fully reopen with limits only on spectator capacity; overnight camps will be permitted with limits on camper cohorts; workplaces must continue to report cases to government for followup and public health-confirmed transmission of COVID-19 in the workplace may result in workplaces being ordered to close for a minimum of 10 days; and remote working will no longer be required or recommended.

  • PH order #13: Effective August 28, 2021: masks must be worn in all indoor public spaces, except when engaged in physical activity; Effective September 3rd only full immunized people can participate in: indoor & outdoor ticketed sporting events and concerts, indoor theatre/dance/symphony events, restaurants (indoor and patio dining), nightclubs and all other licensed premises, casinos, bingo halls and VLT lounges, movie theatres, gyms, fitness centres and indoor sporting and recreational facilities (excluding youth recreational sport), organized indoor group recreational classes and activities, and indoor recreational businesses. Children 11 and under who are not eligible to be immunized will be able to attend events and activities with a fully immunized adult.

  • PH order #14: Effective October 5, 2021: a capacity of 25 people at indoor public events that include unvaccinated guests, although there will be a one-week grace period for weddings and funerals. Those who allow unvaccinated people on their property can now only have 10 guests outdoors, while indoor home gatherings with unvaccinated attendees are restricted to hosting one other household. Indoor religious services, already capped at 50 per cent capacity, are now limited to 33 per cent if they allow unvaccinated people to attend. In the southern health region, where vaccination rates are low, retail businesses are limited to half capacity. Across the province, outdoor public gatherings are capped at 50 people, down from 500. There are exceptions for major sporting events and festivals.

  • PH order #15: Effective November 13, 2021: This applies to the Southern Health-Sante Sud health region only; services restricted to fully immunized people and those under 12 who are not eligible for the vaccine may occur without capacity limits; and the municipalities of Cartier, Headingley, Macdonald, Ritchot (Niverville-Ritchot), St. Francois Xavier and Tache that are geographically located in the Southern Health-Sante Sud health region, are exempt and considered to be part of the Winnipeg Capital Region. Provincewide, proof of at least one dose of vaccination, or a recent (within 72 hours) negative test result will be required for 12 to 17 year olds for indoor recreational sports: there will be a grace period until Dec. 5 to allow individuals who are not yet fully immunized to comply, with the order to be in effect at 12:01 a.m. on Dec. 6; and negative tests need to come from a participating pharmacy as provincial testing sites should only be accessed by symptomatic individuals, or those who are required to take a PCR test by public health.

  • PH order #16: Effective December 21, 2021: private indoor gatherings are limited to 10 additional people plus the household if all are fully vaccinated (youth aged 12 and under are exempt); private indoor gatherings are limited to five additional people plus the household if any of the individuals are eligible but unvaccinated (youth aged 12 and under are exempt); indoor and outdoor sporting and recreation capacity is reduced to 50 per cent for spectators, while games and practices can continue no tournaments will be permitted; large group gatherings will be limited to 50 per cent capacity with proof of immunization; gyms, movie theatres, museums and libraries are limited to 50 per cent capacity with proof of immunization required everywhere except libraries; restaurants and licensed premises are limited to 50 per cent capacity and seated service only with a maximum of 10 people per table and proof of immunization required; and faith-based gatherings are limited to 50 per cent capacity with proof of vaccination, or 25 per cent capacity or a total of 25 people, whichever is lower, when proof of vaccination is not required.

Transmission, Acquisition, Cluster, and Special Events


Transmission Event
    In PHIMS, transmission Events are places cases have visited and may have transmitted to the infection to other contacts during the communicability period. The period of communicability is currently defined as the period extending from 48 hours prior to the development of obvious symptoms in the case until the case is no longer infectious.
Acquisition Events
    In PHIMS, acquisition events are places cases visited during their incubation period (includes the 14 days before symptom onset date) and may have contracted COVID-19.
Cluster and Special Events
  • Cluster are called when transmission is highly suspected or confirmed in:
    • a setting with three or more cases from at least two separate residences (e.g., social gatherings) or
    • two or more cases in congregate settings such as apartments, assisted living facilities, school/daycares etc.
  • Special investigations are requested for food processing plants as well as congregate settings where mobile testing has been requested to assist with linking requisitions.
Limitations
  • The transmission and acquisition events entered into PHIMS are possible sources of settings/locations. A case may have attended a place during the communicability period (for transmission events) or the incubation period (for acquisition events) but no transmission/acquisition occurred. In addition, cases may have visited multiple places during the communicability or incubation periods.
  • Where people go is tightly tied to where they can go (due to current restrictions/public health orders). Therefore, acquisition, transmission, and cluster settings/locations follow the trends in the sector restrictions.
  • Transmission and acquisition data are subject to recall bias. Cases may not remember previous events or experiences accurately or omit details: the results should be interpreted cautiously.
  • The majority of COVID-19 transmission occurs among close contacts, e.g., household contacts etc. The cluster analysis does not look at the transmission within households.
  • Important factors that facilitate transmission are the number of people that are gathering and how and where they are gathering (e.g., ability to physical distance at work, ability to limit number of contacts).
  • The cluster data is a sampling of clusters that occurred. Some clusters were not reported to Epi and Surveillance due to changes in public health processes.
  • Some settings were difficult to assess. For example, retail may be difficult to assess as many people spend brief periods of time in stores and may not know the people they have been exposed; this makes it more difficult to link cases together by place and time than at a school or child care centre.

Risk Factors

Risk factors for cases are retrieved from public health follow-up investigation reports of cases and entered into PHIMS. Risk factors indicate if a case is at higher risk for COVID-19 infection or potentially more severe outcomes as a result of COVID-19 infection. Common risk factors include:

  • People aged 65 years and older
  • Residents in a long-term care facility
  • Close contacts to a case
  • People with underlying health conditions

Symptoms

Symptoms of COVID-19 cases are retrieved from public health follow-up investigation reports of cases and entered into PHIMS. Symptoms range from no symptoms, mild or moderate symptoms to severe illness. Common symptoms have included cough, fever, difficulty breathing, and pneumonia in both lungs. In severe cases, infection can lead to death. COVID-19 can be transmitted to others from asymptomatic cases and those who have not yet developed symptoms (pre-symptomatic). Pre-symptomatic cases can transmit COVID-19 up to two days prior to developing symptoms.

Symptoms take an average of 5-6 days to appear after exposure to COVID-19. However, symptoms may take up to 14 days to appear.

Underlying Illness

Validated algorithms developed by the Canadian Chronic Disease Surveillance System (CCDSS) are used to define the common chronic conditions of COVID-19 cases using administrative health records maintained by Manitoba Health, Seniors and Active Living. (MHSAL).

Vaccination Status

To improve accuracy of assessment, cases were included based on time of infection:

  • Onset date for symptomatic cases
  • Specimen collection date for asymtomatic cases

Relative Risk for Severe Outcomes

In this calculation, a measurement combining persons and time as the denominator in incidence rates was used to account for varying days that individuals were at risk of developing severe outcomes.