Estimating the percentage and number of people with indications for HIV pre-exposure prophylaxis (PrEP) within two key populations, Canada, 2021.

OBJECTIVES: HIV pre-exposure prophylaxis (PrEP) is proven effective for HIV prevention and recommended for individuals at ongoing and high risk of HIV, including gay, bisexual, and other men who have sex with men (GBMSM) and people who inject drugs (PWID). We used existing national survey data to measure PrEP need in both populations and calculate percentages of use among those meeting indications within each group. METHODS: We conducted a secondary data analysis of nationally representative data to estimate the percentage of GBMSM and PWID meeting PrEP indications based on 2017 Canadian guidelines. We applied these percentages to recent population size estimates for both groups to estimate the number of people having PrEP indications in each group. Where available, we also used survey data to determine the percentage of people with indications who were not taking PrEP at the time of the survey. RESULTS: An estimated 24.1% (95% CI 13.3-39.7%) or 99,300 (95% CI 54,800-163,600) of GBMSM had PrEP indications in Canada as of 2021. The corresponding percentage and number for PWID were 22.3% (20.8-22.8%) and 22,400 (20,900-23,900). Two-thirds of GBMSM participants (Sex Now 2019 and 2021) who had PrEP indications were not taking PrEP at the time of the surveys. None of the participants with PrEP indication in the Tracks survey (2017-2019) among PWID reported PrEP use. CONCLUSION: In Canada, the estimated number of people with PrEP indications among GBMSM and PWID far exceeded documented levels of use. Uptake of PrEP was lower among PWID compared to GBMSM. Efforts to improve PrEP access and uptake could help reduce HIV transmission in Canada.