Transmission occurs just when you turn ill and at the beginning of the course of the disease. There are clear indications that the risk of transmission is relatively high one to two days before the onset of symptoms. Contact tracing is therefore performed from 48 hours prior to the onset of symptoms.
Very few people turn ill more than 8–9 days after being exposed to the virus. Quarantine time is therefore set at 10 days.
Those that have had COVID-19 are exempt from quarantine for six months
If you have had a confirmed (laboratory tested) COVID-19 infection within the last six months, you are exempted from quarantine. This also applies to travel quarantine.
Persons who have had a COVID-19 infection are predominantly likely to be protected against a recurrence of the disease, but it is not yet known for how long this protection will last. Anyone showing symptoms of an acute respiratory infection shall, regardless of previously confirmed COVID-19 or not, stay at home until they are free of symptoms.
Ending of isolation
You should be completely free of symptoms in order to end the isolation. You need to be free of symptoms for 72 hours with a period of at least eight days having passed since the first symptoms appeared. For persons in hospital or who undergo immunosuppressant treatment the requirement for isolation may be longer.
Your isolation period also ends even in a situation where other members of your household are still in isolation or in quarantine.
The Norwegian Institute of Public Health provides advice on isolation and how long you should be in isolation (in Norwegian).
Can the virus be transmitted by people who do not display any symptoms?
While the most typical route of transmission is via a person who displays symptoms, infection can also occur just prior to symptoms developing.