A new AIDS prevention drug should be approved for use by intravenous drug users, U.S. health experts have said.

The anti-retroviral drug, which has recently been approved for prescription to some other high-risk groups, could soon be given to people who inject heroin and methamphetamine.

After reviewing the results of a study, carried out by Centres for Disease Control and Prevention (CDC) and the Thai government, health officials recommended that the drug, tenofovir, should be taken daily by drug users.

It has already been approved for use by high-risk gay men and heterosexual couples, CBS News reported.

To conduct the study, scientists followed more than 2,400 drug users at clinics across Bangkok, in Thailand.

Half were given a daily dose of tenofovir, which is sold as Viread, while the other half were given a placebo.

The patients were followed for four years during which time 17 of those taking the preventative drug contracted HIV, while 33 of the people taking the placebo became infected.

Therefore, it was concluded that the drug reduces HIV risk by 50 per cent.

Dr Jonathan Mermin, director of AIDS prevention for the CDC, told CBS News that ‘this study completes the story’ about how HIV drugs can protect people at highest risk of infection.

Currently, the only HIV prevention drug which is available for use in the U.S. is Truvada which is prohibitively expensive at $14,000 a year.

The tenofovir which was used in the study costs just $360 a year per patient.

According to researcher, Dr Michael Martin: ‘We now know that pre-exposure prophylaxis can be a potentially vital option for HIV prevention in people at very high risk for infection, whether through sexual transmission or injecting drug use.

‘Adherence was a key factor determining efficacy in our trial among people who inject drugs.’

The drug, tenofovir, which is sold as Viread, reduces a person’s risk of contracting HIV (pictured) by up to 50 per cent

Scientists are also working on an HIV vaccine but the U.S. government recently stopped trials of the experimental vaccine after an independent review found it did not prevent HIV infection or reduce the amount of HIV in the blood.

The research, started in 2009, it is just the latest in a series of failed attempts to develop a vaccine for the virus.

In the U.S. intravenous drug users account for about one in 13 new HIV infections but in the countries of Eastern Europe and central Asia, they make up 80 per cent of those newly infected.

According to the National AIDS Trust 96,000 people in the UK are currently living with HIV. Of these people, 22,600 are thought to be unaware of their infection.

In 2011, only one per cent of people with HIV in the UK died.

The biggest group of HIV positive people in the UK are men who have sex with men – they account for about 40,000 of the HIV infected population.

Read More: Daily Mail