At least 27 confirmed measles cases have now been tied to the Urkult folk-music festival held in early August, with three new infections reported on Friday alone, after initial reporting identified five cases.
The outbreak's centre of gravity has shifted toward Södertälje, where Stockholm infection-control officials say the most cases are concentrated, as organisers of Saturday's Järna cultural festival pressed ahead with preparations. Most of those infected had not been vaccinated against measles.
Health authorities across the Nordic region are monitoring possible cross-border spread. One infected person travelled on ferries between Sweden and Åland last week, and the Finnish Institute for Health and Welfare confirmed one Finnish festivalgoer tested positive. Norway's public-health institute said it has not yet received reports of infected Norwegians, though some attended. Social Affairs Minister Jakob Forssmed said there is no risk of widespread transmission.