The search for new ways to curb HIV transmission received a badly needed boost last week.

On 22 February, researchers reported that drug treatment against the herpes simplex 2 virus cuts levels of HIV RNA in the blood and genitals of women infected with both viruses (N. Nagot et al. N. Engl. J. Med. 356, 790–799; 2007). The researchers suggest that controlling herpes may thus also control the spread of HIV. Studies are under way to test the idea.

The following day, two large controlled trials on male circumcision in Uganda and Kenya were published (M. L. Newell & T. Bärnighausen Lancet 369, 617–619; 2007). Both trials had been stopped early by their funder, the US National Institutes of Health, because the effects of the procedure were already clear. Together with a previous study in South Africa, the results show that circumcision can reduce a man's risk of HIV infection by 50–60%.

The task now is to roll out circumcision in countries that would most benefit, where HIV rates are high and the virus is spread mainly through heterosexual sex. A working group convened by the Joint United Nations Programme on AIDS and the World Health Organization will hold a consultation on 6 March to discuss how and where circumcision should be provided.