An inflatable festive costume worn by a hospital staff member is suspected of being the source of a COVID-19 outbreak which has infected 44 and killed one in the US.

Officials at the Kaiser Permanente San Jose Medical Center in California are investigating the possibility that a staff member who dressed up in an inflatable tree costume to cheer patients on Christmas Day may have sparked the ED cluster.

Hospital spokesperson Irene Chavez said the hospital began an investigation after 44 ED staff members tested positive for coronavirus between 27 December and 3 January.

One of the possibilities the hospital was exploring was that a staff member who dressed up in an air-powered costume might have fanned the outbreak.