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.

Learn more about lenacapavir, the most effective HIV treatment and prevention drug, and how its cost could cause a setback.