Sexually-active young women and girls aged 15 to 24, one of the most high-risk groups for HIV infection, will be targeted by Kenya's government's roll-out of a new drug intended to protect HIV-negative people to reduce their chances of contracting the virus.

Despite saved and improved lives thanks to prevention and treatment efforts, in many countries including Kenya, stigma and discrimination prevent at-risk groups from accessing vital prevention, testing and treatment and care services. This means that many people are unknowingly living with HIV, or being diagnosed when HIV becomes harder to treat.

Pre-Exposure Prophylaxis (PrEP) is a preventive treatment which involves people who are at very high risk of HIV infection taking a combination of HIV medicines sold under the name Truvada, on a daily basis. This antiretroviral pill can reduce the risk of HIV transmission by at least 90%, if taken daily with strict adherence, according to experts.

A scaled-up strategy, which follows years of clinical work and clinical trials, will be launched on 4 May by Partners Scale-up Project, spearheaded by the government in collaboration with partner organisations.

According to Daily Nation newspaper, the studies focused on several groups, including young women and girls, couples where only one partner is infected and people who inject drugs, as well as sex workers and men who have sex with men.

Young women and girls aged 15 to 24 are especially targeted because they are three times more likely to contract the virus than boys and men in the same age group. In 2015, a third of the 71,034 Kenyans aged 15 and above who got infected with HIV were young women, according to the Kenya Aids Response Progress Report 2016.

One in four young Kenyan women aged 15 to 24 do not know that using condoms during sexual intercourse, or having sex with an infected partner, can reduce the risk of contracting HIV.

Truvada costs Sh3,700 (£27.7, $35.8) per month and its generic equivalent is Sh413 (£3,1, $4). Cost may be higher after consultation or laboratory fees are introduced.