HIV pre-exposure prophylaxis (PrEP) with Truvada was the subject of controversy recently when plans to roll out a widely anticipated HIV prevention programme for men who have sex with men stalled after NHS England said it was not their responsibility to fund the drug.
The high court subsequently ruled that PrEP can be provided on the NHS.
The Proud trial, published in 2015, showed that rates of HIV infection can be significantly lowered by giving Truvada to gay men when they are healthy.
Among 544 men attending sexual health clinics in England who were at high risk of HIV infection, the incidence of new infections was reduced by 86% with PrEP (90% CI 64–96, p=0.0001), at 1.2 per 100 person-years in those given emtricitabine/tenofovir immediately compared with 9.0 per 100 person-years in those for whom prophylaxis was deferred for a year (absolute difference 7.8 per 100 person-years, 90% CI 4.3–11.3).
In the iPrEx study, 2499 HIV-seronegative men or transgender women who have sex with men and were considered at high risk of HIV infection were randomly assigned to receive emtricitabine/tenofovir or placebo.
Among the 100 participants who developed HIV infection over a median follow-up period of 1.2 years, 36 were receiving emtricitabine/tenofovir and 64 were receiving placebo, indicating a relative reduction of 44% in HIV incidence with the antiretroviral regimen (95% CI 15–63; p=0.005).
Partners PrEP enrolled 4758 HIV-1 serodiscordant heterosexual couples in Kenya and Uganda. The seronegative partner in each couple (male in 62% of cases) was randomised to receive emtricitabine/tenofovir, tenofovir alone or placebo for up to 36 months.
The incidence of HIV-1 infection per 100 person-years in seronegative patients was 0.65 among those who received tenofovir and 0.50 among those who received emtricitabine/tenofovir, compared with 1.99 in those given placebo.
The differences translated into relative reductions in HIV incidence of 67% with tenofovir prophylaxis (95% CI 44–81; p<0.001) and 75% with emtricitabine/tenofovir prophylaxis (95% CI 55–87; p<0.001). There was no significant difference in the protective effects of the two regimens (p=0.23).
The dose of Truvada for PrEP is the same as for HIV treatment: one 200mg/245mg tablet once daily.