HIV prevention continues to be a public health priority in British Columbia. Incidence and prevalence are two measures of disease frequency used to inform our response to the HIV epidemic. Incidence is the number of new infections that occur in an area over a year, while prevalence is the total number of people living with HIV in that area in that year.
Routine surveillance of HIV is based on new diagnoses of HIV (i.e., case reports of HIV) [BC CDC 2016 Annual HIV Report]. However, because people can be living with HIV for a long time before they are diagnosed, the number of new diagnoses of HIV is only an approximation of HIV incidence. Similarly, accurate prevalence estimates need to account for migration (i.e. people living with HIV moving into or out of BC) and death, which are not available with routine surveillance. For these reasons, mathematical models are needed to incorporate various sources of knowledge about the HIV epidemic to better estimate HIV incidence and prevalence in the population.
The Public Health Agency of Canada (PHAC) has recently released national estimates of HIV incidence and prevalence for 2016 based on modelling using multiple data sources [Canada Estimates]. We have summarized PHAC’s estimates of HIV incidence and prevalence for the province of British Columbia for 2014 and 2016.
Note that the 2014 estimates presented here differ from those that were previously published [Smart Sex Resource]. This is because the methodology for calculating HIV incidence and prevalence has been revised. The revised methodology has been applied to generate both the 2014 and 2016 estimates presented here.
1) The number of new HIV infections (incidence) has remained stable from 2014 to 2016
Overall, the incidence of HIV has been decreasing in BC since the 1980s. (Figure 1)
Figure 1: Estimated HIV Incidence in British Columbia, 1975-2016
An estimated 232 (range 130-400) people acquired HIV in BC in 2016 compared to 226 (range 150-301) in 2014. (Table 1) About 60% of incident HIV infections were among gay, bisexual, or other men who have sex with men (gbMSM) and 6% occurred among people who inject drugs (PWID). It is also estimated that 30 people who identified as Indigenous acquired HIV infection, which represents 13% of new infections in 2016.
The estimated number of new HIV infections has decreased in 2016 among gbMSM and Indigenous populations compared to 2014, but increased slightly among PWID and heterosexual people who were born or resided in countries where HIV is not endemic (i.e. non-endemic countries).
Table 1: Estimated HIV Incidence in British Columbia in 2014 and 2016
2) The number of people living with HIV (prevalence) has remained relatively stable from 2014 to 2016
It is estimated that 11,621 (range 10,200-13,040) people were living with HIV in BC at the end of 2016, compared with 11,660 (range 10,250-13,070) in 2014. Of the 11,621 people living with HIV at the end of 2016 in BC (Table 2):
- Nearly half (49%) were gay, bisexual, or other men who have sex with men (gbMSM).
- Just under one quarter (23%) were people who reported a history of injection drug use.
- Approximately 1 in 7 (15%) were Indigenous.
Table 2: Estimated HIV Prevalence in British Columbia in 2014 and 2016
PHAC HIV estimates compared to routine surveillance in BC
Overall, the HIV incidence estimates from PHAC are consistent with BCCDC’s HIV surveillance data, which have similarly found a stable or slight decrease in the number of new HIV diagnoses and almost 60% of new diagnoses being among MSM. The stable prevalence may reflect the low number of incident HIV cases each year and a generally low rate of mortality due to improved treatment for HIV.
These estimates, taken with routine surveillance of HIV, are helpful to measure our progress towards ensuring people living with HIV are aware of their diagnosis and engaged in care. This includes addressing stigma around HIV and improving access to prevention, testing, and treatment services that are culturally safe.
Provincial estimates are shown in the BC Centre for Disease Control HIV Annual Report, 2016 (http://www.bccdc.ca/health-professionals/data-reports/communicable-diseases/hiv-aids)
National estimates are presented in more detail in Estimates of HIV incidence, prevalence, and Canada’s Progress on Meeting the 90-90-90 HIV Targets, 2016 (https://www.canada.ca/en/public-health/services/publications/diseases-conditions/summary-estimates-hiv-incidence-prevalence-canadas-progress-90-90-90.html).
Previously published 2014 provincial estimates are described in SmartSexResource (https://smartsexresource.com/health-providers/blog/201606/hiv-prevalence-and-incidence-estimates-british-columbia-and-canada-2014)
Public Health Agency of Canada (PHAC)