Understanding Canada’s progress towards global HIV targets
The Public Health Agency of Canada (PHAC) recently released an infographic with national estimates on Canada’s Progress Towards Ending the HIV Epidemic. These estimates help provide an understanding of the effectiveness of current responses to HIV in Canada and can help identify areas for improvement to guide HIV prevention and care work. However, it can sometimes be difficult to understand what the estimates are really saying. So, let’s explore some helpful tips for interpreting the data.
What do the HIV estimates tell us?
Progress towards the 95-95-95 global targets are evaluated by using four measures:
- the estimated number of all people living with HIV in Canada;
- among those estimated to be living with HIV in Canada, the number and proportion of people who were diagnosed (referred to as the first target);
- the number and proportion of people who have been diagnosed with HIV and who are on antiretroviral treatment (ART) (referred to as the second target);
- the number and proportion of people on ART who are virally suppressed (<200 copies/ml) (referred to as the third target).
Based on the recently released estimates, we know that in Canada in 2022:
- there were an estimated 65,270 people living with HIV;
- 89% of people living with HIV were diagnosed;
- 85% of people diagnosed with HIV were on treatment;
- 95% of people on HIV treatment had a suppressed viral load.
Canada has reached the third ’95’ target and is closing the gap for the first two targets.
How has Canada’s progress towards the global HIV targets changed since 2020?
It is important to note that the newly released estimates data cannot be directly compared to the previously released estimates for 2020 (released in 2022). This is because all estimates are based on mathematical modelling, which requires some assumptions about unknown data, such as people who have undiagnosed HIV. As time goes on, we acquire real-world data that tell us how accurate these previous assumptions were, and we modify our methodology based on new information. For example, with enough time, provinces and territories have a chance to update primary data with missing or new information and remove duplications. Because the new estimates have been calculated with a different methodology than the previous estimates, comparing them would be like comparing apples to oranges!
Estimates published using the most recent data and methods replace all previous estimates. The 2020 estimates will be re-calculated using the most recent data from each province and territory, but these are not yet available. When the revised 2020 estimates are released, we’ll be able to compare progress in 2020 to 2022… comparing apples to apples!
Other international organizations such as the European Centre for Disease Prevention and Control, U.S. Centers for Disease Control and Prevention, Public Health England, UNAIDS and the Kirby Institute in Australia also revise previous estimates based on updated data and new methods.
Why does the estimated number of new HIV infections differ from the data shared in the HIV in Canada, Surveillance Report, 2022?
There are two different types of epidemiological data available. They may seem similar, but they have important differences. The HIV estimates from Canada’s Progress Towards Ending the HIV Epidemic provide an overview that represents all people estimated to be living with HIV (both diagnosed and undiagnosed), whereas the surveillance reports provide information on the number of people who were diagnosed with HIV in that calendar year.
For example, the estimates show that an estimated 1,848 new infections occurred in Canada in 2022. This number represents all people who acquired HIV that year, whether they were diagnosed or not. Whereas in the surveillance report, there were 1,833 newly diagnosed cases in 2022, which represents only those who received a positive diagnosis from an HIV test that year.
The number in the surveillance report does not include the undiagnosed and does include people who acquired HIV in a previous year but were only diagnosed in 2022. So reported HIV diagnoses are not a true reflection of HIV incidence (or a new infection) in that year.
How is PHAC able to estimate the number of people living with HIV who are not yet diagnosed?
It is impossible to know the exact number of people who have acquired HIV and not yet tested, but we are able to estimate an approximate number.
Surveillance data on new diagnoses and data from specialized lab tests, along with assumptions in the mathematical model, are used to estimate how many of the newly diagnosed individuals likely acquired HIV recently, versus those who may have been living with HIV for a while and were not aware of their status. This gives us some information about how many people had undiagnosed HIV, which can then give us a better understanding of the estimated proportion of people living with undiagnosed HIV each year. This information is combined with other data on deaths and migration, allowing us to estimate the total number of people living with HIV in Canada.
The method used in Canada is similar to what is used in Europe, the United States and Australia.
Why is PHAC releasing 2022 estimates in 2024?
HIV estimates are developed using a range of data that comes from the provinces and territories. As each province and territory has their own reporting approach, the data needs to be standardized before they can be combined to produce estimates at the national level. Gathering and preparing the data can take time, so estimates are being published for 2022 as that is the most recent year for which complete data are available.
How has the COVID-19 pandemic had an impact on the estimates?
The COVID-19 pandemic had many impacts, both known and unknown, on access to HIV testing, prevention and care services, as well as on surveillance activities in Canada. For this reason, data for 2020 to 2022 should be interpreted with some caution. The true impact and lasting effects of the COVID-19 pandemic on HIV transmission in Canada may become clearer with continued collection and analysis of data in the years to come.