Voucher scheme to encourage young South African women to take PrEP has modest impact

A 12-month trial that offered adolescent girls and young women in South Africa shopping vouchers for three months as an incentive to take tenofovir‐based pre‐exposure prophylaxis (PrEP) found it only made a modest difference to longer-term adherence.

The 12-month 3Ps for Prevention Study took place between 2017 and 2018 and involved 200 young women (aged 16 to 25) from a township in Cape Town.

The median age of participants was 19. Around 86% had a primary sexual partner and had been in this relationship for around 12 months. One in five (20%) had a partner who was at least five years older, 55% did not know if their partner had other partners, and 17% were aware their partner had additional partners. Around a third (32%) had a sexually transmitted infection.

Most participants said their partner was HIV negative (55%) or did not know their partner’s HIV status (45%). Only one participant reported having a partner who was living with HIV.

Researchers took blood spot samples from participants at months 1, 2, 3, 6, 9 and 12 to assess how many PrEP pills each participant was taking. Participants were also tested for HIV and pregnancy at each visit.

High PrEP adherence was defined as taking four or more pills per week for the previous four to six weeks. A US study among men who have sex with men found this level of PrEP use made it 100% effective. It should be noted, however, that studies among women suggest that PrEP may need to be taken every day in order for it to be 100% effective all the time.

At months one, two and three, half of the participants who had high PrEP adherence received a 200 Rand (US$13) shopping voucher at their next visit, while the other half of participants were only given their PrEP-level results. At month four and for the rest of the trial all participants received PrEP-level results only.

Across both groups, 99% of participants had taken at least some PrEP pills after one month, 97% after two months and 94% after three months.

At month three, 56% of women in the incentive group and 41% of women in the control group had high PrEP adherence.

But the modest difference between groups had decreased at six months and was roughly similar after a year. At six months, 14% of participants in the intervention group had high adherence compared to 8% in the control group. At 12 months, high adherence was 8% in the incentive group and 5% in the control group.

This difference between groups when vouchers were on offer may indicate a potential role for incentives. But these incentives need to have a stronger and more lasting effect on PrEP adherence in order to be cost‐effective.

Just over half (54%) of all participants stayed in the trial for the whole 12 months. Most participants who stopped PrEP entirely did so due to missed visits or because they felt they were at lower HIV risk or were tired of taking PrEP pills.

Overall, 44% received sufficient refills to take PrEP for the entire time. An additional 14% stopped then restarted PrEP. This restart level is higher than levels reported by other similar PrEP trials. Researchers are now in the process of interviewing participants who restarted PrEP to establish whether some were only using it when they felt they were more at risk.

No participant contracted HIV during the study. Additional research is needed to understand the level of protection against HIV among young women with imperfect adherence to PrEP.

Providing long‐acting PrEP injections or PrEP pills that people need to take less often, alongside adherence support, would help to increase the options for young African women.