Amendments to the Communicable Diseases Act came in to force on 22 February.
They give new powers to regional authorities, meaning that they are now able to enforce tighter restrictions on businesses and leisure activities, including the ability to force venues to close for up to two weeks.
The amended law also gives regional authorities the power to reduce the permitted capacity of public transport and makes it easier to test passengers arriving at Finnish ports and airports for the virus.
The powers given to the authorities vary by region and are guided by THL's assessment of the coronavirus pandemic in each hospital district.
What are the rules?
The Finnish Institute for Health and Welfare (THL) divides areas into three categories depending on coronavirus infection rates. They are "base level" (the lowest rate of infection), "acceleration stage" (meaning the rate of infection is rising) and "spreading stage" (the highest rate of infection).
In areas at the base level, companies and venues must provide facilities for hand washing. This means, for example, offering hand sanitiser for customers or activity participants to use. They must also clean their facilities more thoroughly and offer information to customers or service users on how to prevent the spread of the coronavirus.
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Authorities in areas that are in the acceleration phase can oblige businesses and venues to enforce social distancing measures. How best to do this is left up to businesses and venues to decide, but it could include measures such as staggering timetables, reducing capacity or requiring customers to remain at safe distances from one another.
The Finnish Transport and Communications Agency (Traficom) can also impose up to a 50 percent capacity limit on public transport in areas that are in the acceleration phase.
Areas in the spreading stage of the pandemic can be subject to the strictest restrictions of all. In this phase, municipal or regional authorities can order the closure of businesses or facilities for a period of two weeks. This restriction can only be applied to the facilities and spaces that are set out in the amended Communicable Diseases Act.
These include gyms, indoor sports facilities, public saunas, swimming pools, dance halls, amusement parks, indoor play areas and public seating areas in shopping centres. The rules do not apply to private or family activities.
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What do businesses say?
Janne Patjas, owner of the Ykkönen Fitness Centre in Kouvola, told Yle he thought the restrictions on gyms were unfair, as facilities open round the clock would allow people to work out while maintaining social distancing.
"People who want to stay farther apart and work out in the quietest possible place will train early in the morning or late at night," Patjas said.
According to Patjas, participation in group sporting activities has already dropped, with around half as many people taking part as usual.
But Kirsi Ruuhonen from the Ministry of Social Affairs and Health emphasised that the decision to close businesses and facilities would not be taken lightly.
"Closing premises will always be a last resort. We are not currently in a situation where such closures should be ordered right away on Monday, but the situation is fluid and regional authorities will make the call," she said.