Tecovirimat is effective against human monkeypox virus in vitro at nanomolar concentrations

The ongoing monkeypox virus (MPXV) outbreak is the largest ever recorded outside of Africa. We isolated and sequenced a virus from the first clinical MPXV case diagnosed in France (May 2022). We report that tecovirimat (ST-246), a US Food and Drug Administration approved drug, is efficacious against this isolate in vitro at nanomolar concentrations, whereas cidofovir is only effective at micromolar concentrations. Our results support the use of tecovirimat in ongoing human clinical trials. Tecovirimat blocks replication of 2022 monkeypox virus isolate in vitro, supporting its use in ongoing human clinical trials.