The Food and Drug Administration approved the preventative use of lenacapavir, made by Gilead Sciences, on Wednesday. Experts say lenacapavir is easier to administer, and each dose lasts longer compared to other medications.

Clinical trials have shown that six-monthly injections of lenacapavir are almost 100 percent protective against becoming infected with HIV. But big questions remain over the drug’s affordability.

The approval could slow new infections and move the world closer to eliminating HIV. But huge obstacles remain.