A total of 26 healthcare employees of the Päijät-Häme Welfare Consortium were quarantined on Monday after being exposed to a patient diagnosed with coronavirus.
The patient had been treated in several different units, leading six other patients to also be exposed.
The patient's symptoms had not been considered to be coronavirus-related, which led to the employees not protecting themselves as effectively as they should have, explained Tuomo Nieminen, chair of the consortium's Pandemic Working Group.
Nieminen added that the quarantined workers have not been tested for coronavirus because they are asymptomatic, and testing for asymptomatic patients is not considered worthwhile because the test result could be negative, even if the patient has the virus.
Healthcare personnel within the Päijät-Häme region were previously quarantined due to exposure to the coronavirus earlier this year, but Nieminen said almost none were subsequently found to have contracted the virus.
Nine seasonal farm workers were also diagnosed with Covid-19 infections in the region in July.
Two new coronavirus infections were detected in the region last week.