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Facts about the virus and COVID-19 disease

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The SARS-CoV-2 coronavirus was discovered in January 2020. New knowledge about the outbreak, the disease and risks will be regularly updated.

Foto: CDC, Alissa Eckert
Foto: CDC, Alissa Eckert

The SARS-CoV-2 coronavirus was discovered in January 2020. New knowledge about the outbreak, the disease and risks will be regularly updated.

About the virus

The novel coronavirus (SARS-CoV-2) is a previously unknown virus but it has some genetic similarities to the SARS virus (Severe Acute Respiratory Syndrome). Both viruses belong to the coronavirus family. The virus that causes MERS (Middle East Respiratory Syndrome) is another coronavirus. 

The coronavirus family includes many different viruses that can cause respiratory infection. Many coronaviruses only cause colds, while others can cause more serious illness and in some cases, death.

Coronaviruses are also detected in animals. In rare cases, these coronaviruses can develop so they can transmit from animals to humans and between humans. This was seen during the SARS epidemic in 2002 (Severe Acute Respiratory Syndrome), where the infection probably came from bats via civet cats and other animals, and MERS (Middle East Respiratory Syndrome) in 2012, where dromedary camels were the source of infection for the virus.

The new coronavirus is believed to come from bats and was transmitted to humans in the end of 2019, either directly or via other animals, but this has not been determined.

It is uncertain how long the virus that causes COVID-19 survives on surfaces but it appears to behave like other coronaviruses. Research indicates that coronaviruses (including current information about the new virus) can survive on surfaces from a few hours to several days. This will vary under different conditions, such as type of surface, temperature, sunlight and air humidity.


As with colds and influenza, the virus is transmitted from the respiratory tract of a sick person in three ways;

  • Airborne through sneezing or coughing, so the virus is inhaled or comes into contact with the mucosa of the eyes, nose or mouth of people nearby.
  • By direct contact when the person who is sick has the virus on their hands and transmits it by contact with others, who then touch the mucosa of the eyes, nose or mouth.
  • By indirect contact when the virus is transmitted onto objects or surfaces (e.g. door handles, keyboards, telephones etc) by sneezing or coughing, or by the sick person having the virus on their hands, and others then touch the contaminated object/surface.

The virus is mainly transmitted by droplets and through contact like other coronaviruses but has also been detected in stools (faeces). A systematic review from the Norwegian Institute of Public Health shows that transmission can mainly be traced back to direct or indirect physical contact but caution must be taken with the use of aerosol-generating procedures in hospitals. The review includes three reviews and 14 primary studies. A weakness of the systematic review is that only four of the studies concern infection with SARS-CoV-2, and three of them are small, with 1, 11 and 36 cases respectively. Nevertheless, the review concludes that there is at present no evidence that airborne transmission plays a key role in the transmission of COVID-19.

Infection from food, water and animals

Currently, there are no known cases of infection via contaminated food, imported food, water or animals. Based on current knowledge of coronaviruses, infection via food and water is considered unlikely.

In the case of swimming pools, the chlorine content of the pool water will be sufficient to inactivate viruses, including COVID-19, although physical contact during bathing could lead to transmission. On 12th March 2020, the Norwegian Directorate of Health announced the closure of swimming pools, water parks etc., to prevent transmission of COVID-19. The closure has been decided as part of the regulations. 

So far, no information has emerged of transmission between animals and humans. People in isolation and quarantine can be together with their pets.

How contagious is it? (R0)

Calculations from China estimate that a person infected with coronavirus infects 2-3 others on average. In comparison, a person with influenza will infect 1-2 people. The calculations for coronavirus are currently very uncertain and will probably be lower in Norway because we have a lower population density and have implemented measures to limit transmission. 


The incubation time (from infection until symptoms appear) is estimated by WHO to be 5-6 days but this can vary from 0 to 14 days.

Symptoms and disease

The new coronavirus causes respiratory infections, ranging from mild symptoms to severe disease and, in rare cases, death.

Some people may have COVID-19 without developing symptoms. This is especially true for children and younger adults. It is unclear to what extent people without symptoms can transmit the disease.

Usually, people who become ill initially experience upper respiratory tract symptoms (sore throat, cold symptoms, mild cough), as well as feeling generally unwell and having muscle pain. Stomach pains may be present and diarrhoea may occur in some cases. The loss of the senses of smell and taste have been reported in several countries.

The course of the disease varies widely between individuals. Currently, the typical courses appear to be:

  • Mild course (majority of sick people, about eight out of ten): Symptoms pass within one to two weeks. These people rarely need treatment from the healthcare service.
  • Moderate course: After 4-7 days of mild symptoms, some people may develop pneumonia with breathing difficulties, worsening cough and rising fever. Some will need to be admitted to hospital. X-ray examination of the lungs may show changes consistent with viral pneumonia (pulmonary infiltrates)
  • Severe course: As for the moderate course, but these people also need intensive care treatment. They may have symptoms for 3-6 weeks. Some of those who become severely ill will die from the disease.

Information about risk factors for severe disease is currently limited. Admission to hospital, intensive care treatment and death are more common among the elderly and people with underlying diseases, particularly among the elderly with underlying diseases, but can also occur among people without known risk factors.

There is no specific treatment or vaccine for the disease.

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SARS-CoV-2 is the name of the virus that is causing the outbreak of COVID-19 disease.

The virus is related to another coronavirus that caused the SARS outbreak in 2002/2003 but is not the same virus.