The first HIV capsid inhibitor may require dosing just once every six months, and few people are likely to have preexisting drug resistance, researchers reported at the 17th European AIDS Conference. GS-6207, from Gilead Sciences, interferes with the viral capsid, the cone-shaped shell that surrounds HIV’s genetic material. In a Phase Ib study, 32 people, mostly new to HIV treatment, received a single injection under the skin of various doses of GS-6207 or a placebo. Ten days after the injection, people who received GS-6207 saw greater viral load declines than those who got the placebo—up to a mean 2.2 log10 drop. Drug levels remained detectable for at least 32 weeks, suggesting that GS-6207 could potentially be administered just twice a year. The most common side effect was mild irritation at the injection site. The capsid inhibitor will now be tested in larger trials of people with multidrug-resistant HIV as well as those starting treatment for the first time.