Sweden's Public Health Agency has reported 21 cases of measles linked to a folk music festival held in the northern part of the country.
The cases were identified in different regions of Sweden, but all have been connected to the Urkult festival, which took place in northern Sweden in late July and early August.
Most of those infected were under the age of 18, and the majority had not been vaccinated.
Authorities tracing contacts
Regional health authorities are now tracing people who may have come into contact with those infected in an effort to contain the spread of the virus.
In a statement, Sweden's Public Health Agency noted that measles outbreaks remain uncommon.
"Measles outbreaks are rare. Vaccination against measles is part of the national childhood immunisation programme, and vaccination coverage is approximately 95%."
High vaccination coverage
Measles vaccination is included in Sweden's national immunisation programme for children, with coverage levels remaining close to 95%, according to health officials.
Authorities are continuing efforts to identify and contact potential exposures linked to the festival.
