HIV-prevention drug Truvada approved

US health regulators have for the first time approved a drug to prevent HIV infection.

Truvada, made by California-based Gilead Sciences, is already backed by the FDA to be taken with existing antiretroviral drugs for people who have HIV.

Studies from 2010 showed that Truvada reduced the risk of HIV in healthy gay men - and among HIV-negative heterosexual partners of HIV-positive people - by between 44% and 73%.

"We know that for HIV-positive people if they consistently take antiretroviral drugs and their viral load is suppressed for them it's almost impossible to transmit the virus."

Truvada is approved in the UK for the treatment of HIV, but not prevention.

In 2011 another study found that Truvada reduced infection by 75 per cent in heterosexual couples in which one partner was infected, according to reports.