It’s not an AIDS vaccine but it may be the closest thing to one so far. A long-acting antiretroviral drug given as an injection every 2 months powerfully protected uninfected people from HIV in a large-scale study that was disrupted by the COVID-19 pandemic. The apparent success—the study has not been published in a peer-reviewed journal or presented to HIV researchers at a meeting—offers a potentially easier alternative to taking daily pills of other antiretrovirals, which has proved difficult for many people.

The strategy of uninfected people taking drugs to ward off HIV, known as pre-exposure prophylaxis (PrEP), earned the U.S. Food and Drug Administration’s blessing in 2012 when the agency approved a daily pill combining two drugs that cripple the virus. In the new study, this combo marketed as Truvada was tested against intramuscular injections of the experimental drug cabotegravir or placebos in men who have sex with men and transgender women. The trial, sponsored by the U.S. National Institute of Allergy and Infectious Diseases (NIAID), began in December 2016 and enrolled more than 4500 participants worldwide, who were randomly assigned to Truvada, cabotegravir, placebo pills, or placebo injections. As of late April, 12 infections occurred in the cabotegravir group versus 38 in the equally sized group that received Truvada. This represents a 0.38% incidence in the cabotegravir arm versus 1.21% in the Truvada one, a 69% difference in new infection rates.

“It’s really exciting,” says Jared Baeten, an epidemiologist at the University of Washington, Seattle, who was not involved in the NIAID trial but conducted a landmark PrEP study of anti-HIV pills (one was Truvada) in Kenya and Uganda. Read more via Science