The Regional State Administrative Agency (Avi) of Southern Finland is expected to order the closure of the facilities used for sports, entertainment and recreation for two weeks beginning 1 April.
In addition to Uusimaa, the decision concerns the areas of the hospital districts of South Karelia, Kanta-Häme and Päijät-Häme.
An amendment to the Communicable Diseases Act, which was to come into force on Wednesday, allows facilities to be closed for two weeks at a time.
The amendment removed the option of keeping open premises used by 10 customers or less at a time.
Avi was to formally announce the closure decision on Wednesday, after the amendment enters into force.
Regional agencies can decide on the matter for two weeks at a time until 30 June.
The decision will close all indoor sports facilities, public saunas, swimming pools, indoor playgrounds, dance venues, facilities for choral singing and amateur theatre, amusement and theme parks, indoor spaces at zoos, and general public spaces in shopping centres, among others. A detailed list of sites to be closed can be found on the Avi website (only in Finnish so far).
Facilities designated for closure may still be used for supervised recreational activities for children born in 2008 and younger. The decision does not apply to professional sports.