A new HIV-prevention drug that offers nearly complete protection with just two injections a year is raising hopes of curbing the global epidemic, but limited supplies are restricting access in many countries. The drug, lenacapavir, developed by American pharmaceutical company Gilead Sciences, is a long-acting form of pre-exposure prophylaxis, or PrEP, which helps prevent HIV infection. The twice-yearly injections could provide an alternative to daily prevention pills and other existing treatments that require more frequent doses.