Attenuated NYCBH vaccinia virus deleted for the E3L gene confers partial protection against lethal monkeypox virus disease in cynomolgus macaques

► NYCBHΔE3L vaccine candidate partially protects macaques from monkeypox virus challenge. ► Potential safer smallpox vaccine. ► Induces 2-fold lower titers of neutralizing antibodies as current smallpox vaccine.