A case series which is the result of an international collaboration across 16 countries is published today (21 July 2022) in The New England Journal of Medicine (NEJM). The study identifies new clinical symptoms of monkeypox infection, which will aid future diagnosis and help to slow the spread of infection. It was carried out in response to the emerging global health threat and is the largest case series to date, reporting on 528 confirmed infections at 43 sites between 27 April and 24 June 2022.