Although they are at risk of exposure to HIV, the rates of coverage and acceptance of PrEP are lower than among adults

During the last joint conference of the British HIV Association (BHIVA) and the British Association for Sexual Health and HIV (BASHH), held at the end of April virtually due to the COVID-19 pandemic, the first results of the implementation study of pre-exposure prophylaxis against HIV (PrEP) in England (the IMPACT study) for the implementation of pre-exposure prophylaxis against HIV (PrEP) in England were presented.

Investigators presented only recruitment data at baseline. Subsequent analyzes will examine the HIV incidence rate among participants during the trial and the causes of infection; evidence of population-level changes in the incidence of HIV and STIs during the trial; and the "PrEP cascade" or the proportion of the English population at risk of exposure to HIV and who have been protected through their participation in the study.

The study ran in England from October 2017 to July 2020. Initially 10,000 places were assigned to the study, but as a consequence of the obvious need for PrEP and the popularity of the study, the study had to be expanded twice, with 26,000 being the number of total number of places. Most English sexual health clinics participated, 157, with a minimum number of 20 participants per center.

At recruitment, the researchers used two different definitions: 'being a candidate for PrEP' and being 'at risk of exposure to HIV'. To be a candidate for PrEP, the main criteria was being gay, bisexual, or a man who has sex with men (GBHSH) or a trans woman. In addition, having had sex without a condom in the previous three months and anticipating doing so in the following three months. Another criterion was having a partner with HIV with a detectable viral load (greater than 200 copies / mL). On the other hand, finding 'at risk of exposure to HIV' was a much broader category that included all people with characteristics that suggested risk of HIV, such as, for example, having frequent tests for detection of HIV and STIs, engaging in sex work for HIV or other STIs, or persons who have been identified through the study of contacts.

In total, the study included a total of 24,255 participants, the majority being cis GBHSH men. A total of 1,038 participants did not belong to this group (4.3% or one in 23 participants). Of these 1,038 participants, just over a third were trans women (359) and just under a third were cis women (333). Twenty-nine percent were men, divided evenly between trans men (152) and cis heterosexual men (150). There were also a small number of non-binary participants (35).


The median age was 33 years in a range between 16 and 86 years. The ages of most of the cis GBHSH men ranged from 25 to 40 years, while the cis women were older than the rest of the participants and the trans women much younger.

Despite the fact that people of African ethnicity have a high rate of HIV diagnoses, only 11% of cis women and 19% of cis heterosexual men were of this ethnic group. The majority of the participants were Caucasian, including 76% of cis GBHSH men, 60% of cis women, and 49% of heterosexual cis men. Among GBHSH men, the largest non-white ethnicity was Asian represented at 5%. Almost 11% of trans women were Asian and very few trans women or men were of Black African or Caribbean ethnicity.

Half of the participants lived in London, although this figure decreased among cis heterosexual women and men and rose to 60% among transgender women. Almost a third of the participants were born outside the UK, except in the group of trans women who 40% were born abroad.

The study offered cis GBHSH participants the ability to start PrEP daily or on demand. Only 15% opted for the on-demand schedule, but the researchers believe that, as others show, this proportion of men who opted for on-demand PrEP would increase over time.

Using the broader definition of being 'at risk of exposure to HIV' and data from both the study and the STI units that participated in the study, the researchers calculated PrEP coverage, that is, the proportion of people who found 'at risk of exposure to HIV' and who were enrolled in the study and acceptance of PrEP, that is, the proportion of people classified as candidates for PrEP who were enrolled in the study.

Most of the cis GBHSH men (93%) were classified as 'at risk of exposure to HIV' and 26% as 'candidates', of which half (13%) were enrolled in the study. 77% of trans women and 65% of trans men were classified as ‘at risk of exposure to HIV’ and the vast majority were candidates for PrEP; 62% of trans women and 50% of trans men who attended STI clinics were enrolled. In contrast, only 5% of cis heterosexual men were considered to be 'at risk of exposure to HIV'. White people born outside the UK were more likely to be at risk of HIV exposure, not because they were cis GBHSH men but because they were a disproportionate fraction of the other groups.

However, the largest discrepancy in both coverage and acceptance was recorded by age groups. Only 8% of those enrolled in the study belonged to the two youngest age groups compared to 16% of the two oldest. Just taking into account the group of cis GBHSH men, it was estimated that only 9% of all those at risk of exposure to HIV between the ages of 16 and 19 were enrolled in the study compared to 28% of those aged between 45 and 49 years (coverage rate). Only 38% of participants classified as PrEP candidates aged 16-19 years were enrolled in the trial compared to 67% of those aged 45-49 (acceptance rate).

In conclusion to these data and in response to the possible reason for this underrepresentation of young people, the study authors note that younger people may have less knowledge about PrEP and about sexual health in general. This could be increased by the reluctance of young people to reveal their sexual practices and behaviors, especially if doctors do not ask direct questions. However, paradoxically, this can lead to an overestimation of risk if doctors make assumptions about the behavior of young people instead of asking them directly. This would tend to increase the number of young people considered at risk of exposure to HIV compared to older people. According to the researchers, the key would be to train doctors to make young people feel comfortable and talk openly about their risks, or lack of risk, of contracting HIV and STIs.


Source: Aidsmap / Own elaboration (gTt-VIH)
References: Sullivan A et al. The HIV pre-exposure prophylaxis (PrEP) IMPACT trial: baseline demographics, coverage and first regimen choice. Fifth Joint Conference of the British HIV Association (BHIVA) and the British Association for Sexual Health and HIV (BASSH), abstract O013, 2021.



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