An injectable drug called lenacapavir achieved 100% effectiveness at preventing HIV infection with just two shots per year in clinical trials. Unlike daily prevention pills that require strict adherence, this drug targets HIV’s capsid protein in a completely new way. Two major trials showed it protects people for at least six months per injection, and researchers are testing whether a single annual shot might work.

From the desk: After 40 years of research, scientists who refused to accept “good enough” just changed what’s possible for millions.