Small implants placed under the skin and vaginal or rectal microbicide inserts could offer convenient new options for pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP). Researchers found that a refillable islatravir implant was well tolerated and produced sustained drug levels for more than 20 months in monkeys. The implants fully protected female and male monkeys against vaginal or rectal infection with an HIV-like virus. Other research teams tested a fast-dissolving tablet containing elvitegravir and tenofovir alafenamide that can be inserted in the vagina or rectum. The inserts were 93% effective at preventing rectal infection in monkeys. The first human study found that rectal inserts were well tolerated and maintained adequate tenofovir levels for 72 hours. When rectal tissue was exposed to HIV, viral replication decreased. In another study, vaginal inserts fully protected monkeys when administered four hours after exposure and 94% effective after eight hours, but this dropped to 77% after 24 hours.