To date, more than 99% of monkeypox cases in Britain are among men, and the majority of those are in men who are gay, bisexual or who have sex with men. The vaccine was originally developed for smallpox, a related disease, but is thought to be about 85% effective against monkeypox. Vaccines have previously been available only for health workers taking care of monkeypox patients or for cleaners disinfecting areas contaminated by the virus.
