The medical community has reached another milestone that could put an end to the decades-long HIV epidemic. The Food & Drug Administration approved Yeztugo (Lenacapavir) Wednesday It’s a twice-yearly injectable for preventing the virus.

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.