The Norwegian Institute of Public Health (Folkehelseinstituttet, NIPH) confirmed the three additional cases on Thursday evening after the country’s first case was reported on Wednesday.
Of the three new infections, two live in Oslo and one in neighbouring Bærum. All have been placed in quarantine at their homes and none are seriously ill.
Two of the three picked up the virus due to the outbreak in Italy and one due to the outbreak in Iran, broadcaster NRK reports.
The first reported infection was a woman in Tromsø who returned from China last week.
That means that none of the four confirmed infections were passed on inside Norway.
Several counties have placed further individuals in home quarantine as they await test results, NRK writes.
NIPH said that, as all four existing cases are linked to infections abroad, there is no current spread of the virus within Norway.
“They are all at home and not seriously ill,” NIPH consultant doctor Are Berg told NRK.
Cases of the virus in Norway were expected by the country’s health authorities, he added.
“We have been expecting this, and it is an unsurprising development with an ongoing spread in Europe,” Berg told NRK.
The consultant doctor urged calm to those who have travelled to countries with outbreaks.
“If you have travelled to any of the affected areas, stay calm. But if you get symptoms, contact your local health authority. There is no need to call (emergency number) 113. Contact your local health care service,” he said.
WHO spokesperson Dr. Margaret Harris told NRK on Wednesday afternoon that it is important for people in Norway not to immediately go to the doctor or hospital if they suspect they have symptoms of the virus.
“Don't go to the hospital. Don't go to your doctor. Know what to do to get treatment. Inform the health authorities and quarantine yourself,” Harris said.
The virus often begins with symptoms resembling a common cold and can develop into respiratory infection. The elderly and people with already-weakened immune systems are most at risk of serious complications.
The WHO doctor noted that most patients do not become seriously ill, but added that they can infect others who may become seriously ill.
“People need to stay calm. Don't let people move around. Hand hygiene is very important. It sounds so simple, but it is not so easy to make sure you wash your hands often enough. Do not scratch your eyes or nose. Cover your mouth and nose if you cough,” Harris said.
Norwegian Directorate of Health director Bjørn Guldvog has said that although the country’s health services were making contingency plans for a situation in which up to 25 percent of the population becomes infected with coronavirus, “this is not the same as me saying I think we will end up in that situation”.