| ce t | Field on Output Sheet | Definition | Explanation | References |
| A12 | Venue air volume | The internal volume of the space in which the scenario takes place. | In order to understand how many virus particles may be in the air, we need to know how many people are in an area, its dimensions, as well as the amount of air in the area. | |
| B23 | Mask protection factors: no mask, cloth or surgical, KN94 or N95, tape sealed or elastomeric filter, N100 / P100 | Different masks offer different levels of safety, blocking various types of particles by filtering the air. Some masks block viruses so that they can’t enter or exit. | We know that masks help stop the spread and the better the mask, the more effective the prevention. This applies both to the person whose risk we are evaluating as well as the others who will be in the space. Each improvement in mask quality from No mask to N95 to Tape-sealed or elastomeric increases the protection by a factor of 10. |
|
| B27, B28 | # of others | The number of other people who do not live with you and are in the room or venue. | In order to understand how many virus particles may be in the air, we need to know how many people are in an area as well as the amount of air in the area. | |
| B30 | Lifetime Risk | The expected lifetime harms from a single COVID exposure. The present value of all the expected harms from a given exposure. The total harm in quality adjusted life years (QALYs) would be valued at the moment of exposure, when the future harm is committed. We take all the known harms from all causes for COVID exposure, weight by their probabilities, and sum them to get the lifetime risk in QALYs. Finally, QALYs are adjusted to value of mortality risk using the Government of Canada’s preferred willingness-to-accept risk factor of $9 to offset a 1 in a million risk of death, see VMR below. We assume that all the potential future harms from a COVID infection, be they hospitalization, death, or reduced ability from long COVID are committed at the moment of exposure. For instance, one person could catch COVID, and then suffer a reduction in their ability to participate in society of 20% over the next 7 years. All of these harms are committed on the day they catch COVID. This harm is discounted using a social discount rate of 2.85%, see SDR below for details. |
Actuaries and policy and health economists have to understand how much people would pay to reduce the risk of death or to live healthier lives. This is often called the willingness-to-pay in economics calculations. That is the equivalent to how much an average Canadian would pay to reduce their risk of mortality. This information is used to evaluate potential risk mitigations, such as seatbelts, and takes both projected death and disability into account. When implement seat belts, how many lives will be saved by vehicle km driven? How valuable is a life to someone? Actuaries do these kinds of calculations. At the level of the society, the cost of the mitigations are weighed against the cost of the life years saved. We can use this to evaluate how much of our “health risk budget” (see definition below) we are spending on an individual event. The value we are using for health risk is $9 for a 1 in a million reduction in risk of death. We “spend” that budget crossing the street, eating food that isn’t great for us, or going hang gliding. |
|
| B6 | Family risk analysis | When 1 person in a family or household is exposed, very often everyone is exposed. The risk estimator by default uses a family as the central unit for risk. We term this method of analysis a “family-wise” risk computation. This is like when you are driving, if there is an accident, everyone in the car could get hurt. This is unlike crossing the road against traffic, where you are the only person at risk. Risk Budget calculation depends on the family risk levels. Average family-medium risk is about $32,000 risk dollars for a single COVID infection. |
The Government of Canada estimates that the average Canadian would pay $9 for a reduction of risk of 1 in a million in death. Averaging across the Canadian population, the average number of expected years of perfect health remaining is 33 years. This then values one year of life in perfect health at $267,000, or $5,140 monthly. | |
| B28 | Health risk budget | One way of evaluating what an acceptable risk is for an individual is to use a “health risk budget”. A health risk budget is an informed way of saying “I am comfortable with taking on a set amount of risk over a given period of time”. For instance, suppose that you want to limit your chance of catching COVID to a 1 in 20 chance over 20 years of typical exposure. Therefore, you would be comfortable with a 1 in 400 chance of catching COVID every year. We term that your “risk budget”. |
The risk calculator currently estimates the committed risk for an average medium risk family at $32,000 per COVID exposure. For this family, with a risk budget of 1 in 400 per year, that works out to $32,000 / 400 = $80 per year. Yearly risks are fairly large, so it may make more sense to do monthly risk budgeting. An acceptable monthly risk budget for this family would be $80 / 12 = $6.67. That is a health risk budget from COVID of $6.67 per month. |
|
| A28 | Maximum lifetime exposure risk | See also: Lifetime Risk | ||
| B5 | Scenario | Situations where one will be at risk of infection. There are many elements in a scenario. We have created standardized estimates for common situations. You can find a list of Standard Scenarios here and request a new scenario here. |
||
| B6 | Household | For the Standardized Scenarios, we use three households configuration, based on Statistics Canada information: Low risk, medium risk, and high risk. If anyone in your household is particularly vulnerable to COVID19, that is reflected in total family risk. For Standard Scenarios, most people would use the Medium risk household. For High Risk household, double the results shown. | **Household, medium health risk Two adults ages 34 – 40, and 1 child, medium risk, 3 vax |
|
| B7 | Venue | A description of the place in which the event will be held. | ||
| B8 | Province | Rates of disease vary across the country so use the province in which the event will take place for Personal Scenarios. The Standard Scenarios use the average Canadian household rates. You can find a list of Scenarios here and request a new scenario here if you don’t see the one you need. | ||
| C2 | Prepared Date | Rates of infection vary over time so for an accurate assessment, use the most applicable version of the scenario in which you are interested. | ||
| C4 | Based on Forecast Data range | In order to provide the most accurate estimates, the team updates the data every other week from COVID19 Resources Canada and other sources. Since the rates of infection vary, use the most recent version of the scenario in which you are interested. | ||
| E28, F28 input | Seroprevalence | Seroprevalence is the number of persons in a population who test positive for a specific disease based on serology (blood test) specimens. | For COVID, there are two different seroprevalence values commonly reported. The first is the proportion of people who test positive for the Spike, or S protein. This is called infection-acquired or vaccine-induced seroprevalence, and it means how much of the population has ever been protected from or infected by COVID. The second is the proportion of people who test positive for the Nucleocapsid, or N protein. This protein is not in vaccines, so you can only get it from natural infection. This is called infection-acquired seroprevalence. To make it slightly more complicated, human immunity to disease doesn’t last forever, so there is some natural waning of protection in both cases if the population hasn’t seen any infections (for N) or vaccinations (for S). This is called seroreversion. You can see the rates of seroprevalence for Canada at https://www.covid19immunitytaskforce.ca/seroprevalence-in-canada/ . |
Link |
| C10 | COVID prevalence Rate | When I’m walking around and meet a random person, it’s helpful to know what the chance is that they have COVID-19. We use the Canadian Infection Rate as the base but we can also select the home province of the people we’ll meet.
Standard Scenarios are calculated using Low, Medium and High sero prevalence rates, as indicated. |
Do with Stef, this requires a good explanation, people will need to select this themselves so need to understand. we’re using “Canadian infection rate” as the generic. | |
| — | eACH Equivalent Air Changes per Hour |
Air changes per hour, abbreviated ACH (rarely ACPH) is a measure used in ventilation calculations to measure the amount of ‘new’ air added or removed from a room. Equivalent air changes per hour, or eACH, on the other hand is a measurement of the ‘equivalent’ amount of air a purifier changes per hour. Air purifiers do not actually bring in new air into a room, or change the air in a room. Instead, they clean the air already existing in the room. |
||
| E13 | Airflow: Good air | Good air is a situation where the air in an area is exchanged at least 6 times per hour. | Good air can vary according to the modelling assumptions of the space. (more to come after the meeting tonight) | |
| E14 | Airflow: Poor air | Anything below 6 eACH is considered Poor air. | For indoor forced air, like in a typical building, the average number of air changes per hour is 0.7. However, COVID naturally decays in the air, and some of it falls out of the air as larger droplets. This provides an extra 0.5 air changes per hour in all room-temperature air. That makes the typical indoor air in a commercial building have an effective air change per hour value of 1.2 eACH. For a house without forced air or a house that is not using a fan, the average number of air changes per hour with outside air is 0.5. Adding in the 0.5 effective air change per hour from COVID decay and settling gives a typical number of indoor effective air changes per hour in a home of 1.0 eACH. |
|
| E15 | Airflow: Wind speed | When an event is held outside we look at the wind speed to help assess the eACH. | ||
| E16 | Airflow: open area | When an event is held outside we look at the degree to which the area is open help assess the eACH. | ||
| E22 | Your activity level: restful, mild exercise, heavy exercise | The degree to which you will come in contact with virus particles in the air is partially driven by the activities you are undertaking. Heavy exercise, or shouting or singing, is the highest risk, mild exercise is lower risk, and the lowest risk for you is when you are restful. | ||
| E28 | Probability someone is infected | This factor is based on the current level of COVID-19 in the community and the density of the people involved in the scenario. | ||
| E30 | Equivalent risks – cigarettes | Thirty minutes of your life expectancy is referred to as a microlife. If you have unhealthy habits, it costs you microlives. If you smoke, each cigarette reduces your life expectancy on average by around 8 minutes, so two cigarettes loses you a microlife. RSE calculates microlives values for risk of smoking 1 cigarette using a factor of $4.28. The intent is to show proxy equivalants of risk of infection in participating in that specific scenario. This activity will result in reducing your life expectancy by this many microlives. |
Link | |
| F61 | Equivalent risks – driving hours | Average US risk of death from collision from driving 100 km by car (1 hour) using a factor of 2.43. The RSE uses that risk factor as a proxy equivalent of the risk of infection. |
||
| Equivalent risks – sedentary, hours TV watching | RSE calculates microlives values for risk of 1 hour of sedentary behaviour, as in watching TV, using a factor of 4.50. | |||
| H12 | Other people’s activity: silent, speaking, shouting / singing, mild exercise, heavy exercise | The degree to which virus particles are expelled by individuals is partially driven by the activities they are undertaking. Shouting, singing, and heavy exercise are the highest risk, speaking is lower risk, and the lowest risk is from individuals who are silent. | ||
| H30 | Likelihood you have COVID when leaving | Very simplified explanation: This is calculated based on the duration, number of others, quality of mitigations, quality of the air, masks, and the level of COVID19 in the community at the time. | Pam – often this % is very low. it undercuts the argument when it’s such a low % even when the Risk Value $ is a teeth sucker. | |
| H5 | Months since your last booster | There is published information on the level of protection from vaccination over time so we take that into account. | ||
| H6 | Number of vaccine doses: | We ask for number of vaccinations and infections to establish the amount of protection you have. | ||
| H8 | Your months since last infection / Novavax: |
There is published information on the level of protection from infection and non-mRNA vaccination over time so we take that into account. | ||
| J12 | Mask protection factors: no mask, cloth or surgical, N95, N99 or tape sealed N95, N99 / P99 / N100 | Masks help stop the spread of infection, and the better the mask, the more effective the prevention. This applies to both the person whose risk we are evaluating as well as the others who will be in the space. | ||
| J23 | Exposure duration time in minutes | The length of time you spend in a potentially infectious environment is a factor used to determine the risk of the overall event. | ||
| J24 | Prior occupancy time in minutes | COVID19 decays and falls out of the air at a predictable rate. The longer a space is empty, the less COVID19 there will be in the air. | ||
| J5 | For your region: | Rates of disease vary across the country so we use the province in which the event will take place for Personal Scenarios. In order to provide the most accurate estimates, the team updates the Estimator data every other week from COVID19 Resources Canada and other sources. The information here reflects the most accurate information available on the Prepared Date. The Standard Scenarios use the Canadian rates. You can find a list of Standard Scenarios here, and request a new scenario here. |
||
| J6 | Override | In creating a Scenario, we are able to override regional seroprevalence in the case of known infection level, i.e. after the event you find out that someone who attended was positive for COVID19, you can more accurately understand your risk with this information. | ||
| J7 | Sum of household risks | To be safe, we assume that if anyone in a household gets infected, everyone is likely to catch it. The Estimator establishes family risk by entering the individual risk of each person in the household based on detailed Individual Risk tables. Family risk is the sum of each individual risk level. Risk estimator shows that LC is 80% of the individual risk level of getting infected. |
||
| J9 | Covid Modeling Mode – Before or After the Event | There is variation in the quantity of COVID that different people leave behind them. We refer to this as viral shedding. Some people are, through no fault of their own, “super-shedders”.
This is how we use this information in our modelling (based on Peng el al. 2022): Before an event: When planning mitigations before an event, we set the model to use the 97.5th percentile of the COVID distribution. This results in a “very bad case” estimate, which helps to evaluate various precautions. This is similar to how we wear a seatbelt every time we are in the car, not only when we are in a high-risk situation. After an event: When evaluating a scenario after the fact, we use the “Average” setting in the model. This is acceptable because there are no longer any ______? mitigations? we can take to make the event more safe. Population modelling: We use Average for situations where we are estimating population risks, because the risk of super-shedders is spread over the entire population. *Repeats of the same event: Repeat calculations cover, essentially, both the before and after situations. We use Average for situations which are repeated because the likelihood of meeting a Super Shedder will be spread over many meetings. |
Our application of this factor is based on the Peng et al shedding analysis. | |
| K30 | Risk if someone at the event has COVID | Based on regional or national infection rates and density of participants, this indicates how many people will be likely to become infected with COVID19 during the event. | ||
| Risk array A30 to L39 |
Good air / Poor air Masked vs unmasked |
In this section we match risk factors to protection that you can use. The easiest mitigation is to wear masks and ask others at the event to wear masks. Another easy way to protect everyone is to hold the event outdoors. Increasing the ventilation in an area by introducing air filtering measures can significantly improve protection as well. |
||
| Used for B & C 33 to 39 | QALY | QALY is a measure of health outcomes, which is the arithmetic product of life expectancy and a measure of the quality of the remaining life-years. | Link | |
| Used for B & C 33 to 39 | Value of Statistical Life (VSL) | Value of Statistical Life (VSL) | Link | |
| Value of Mortality Risk (VMR) | The value of a mortality risk is expressed in terms of dollars per unit of risk reduction per person per year. The risk calculator uses a willingness to pay (WTP) of $9 to reduce the risk by 1 in a million, per Treasury Board guidelines for valuing risk reduction. | “The risk calculator uses a willingness to pay (WTP) of $9 to reduce the risk by 1 in a million…” my mind got stuck here, how the $9 works in the calculations. | Link | |
| Willingness to pay (WTP) or Willingness to accept (WTA) | A measure of value that underpins the economic theory of value is willingness-to-pay (WTP). It is defined as the maximum amount an individual is willing to pay to acquire an outcome. Is it conceptually similar to willingness-to-accept (WTA). Willingness-to- accept measures how much a person would accept (in compensation) for a negative outcome. WTP is often used to refer to both concepts together. | Link | ||
| Social discount rate (SDR) | In human health and environmental goods and services, economic analysis should be carried out using a social discount rate. One approach is to estimate the social time preference rate, which is based on the rate at which individuals discount future consumption and projected growth in consumption. For Canada, the social time preference rate has been estimated to be 2.85%, with a range from 2.6% to 3.18%. | Link | ||
| Risk dollar | A risk dollar is the amount of risk that an individual will pay $1 to reduce. An average Canadian life is currently valued by the Estimator at $9,000,000. |
Link | ||
| Numéraire | The numéraire (or numeraire) is an item or commodity acting as a measure of value or as a standard by which value is computed. |
Disclaimer: Important Notice: If you use this information, you’re doing it at your own risk. We’re sharing it with you as it is right now, and we can’t make any promises about it in future. We don’t promise that it’s good enough to sell, that it won’t cause problems with third party rights, or that it will work for what you need. We also can’t promise you’ll always be able to access it, that it is correct, or that it is safe from viruses or harmful material. Use it carefully!