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Facts about the SARS-CoV-2 virus and COVID-19 disease
About the virus
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.
The novel coronavirus SARS-CoV-2 was first discovered in January 2020. It has some genetic similarities to the SARS virus (Severe Acute Respiratory Syndrome) which also belongs to the coronavirus family. The virus that causes MERS (Middle East Respiratory Syndrome) is another coronavirus.
Coronaviruses are also detected in animals. In rare cases, these coronaviruses can develop so they can transmit from animals to humans and between humans, as seen during the SARS epidemic in 2002. The infection probably came from bats via civet cats and other animals. and , where dromedary camels were the source of infection for the MERS virus discovered in 2012.
SARS-CoV-2 is believed to come from bats and was transmitted to humans in the end of 2019, either directly or via other animals. There is no evidence that mutations (changes in genetic material) that have appeared since the virus was discovered have had any effect on the virus' ability to cause disease.
Research indicates that coronaviruses (including current information about the new virus) can survive on surfaces from a few hours to several days. This depends upon amount of virus, type of surface, temperature, sunlight and air humidity. Experimental studies show that just because a virus can survive on different surfaces does not mean it will cause infection in humans.
Infection with the SARS-CoV-2 virus occurs mainly following close contact (less than 1 metre) by exposure to droplets that contain viruses from the respiratory tract. COVID-19 patients are most contagious in the days around the onset of symptoms. Someone can be infected with SARS-CoV-2 virus without developing COVID-19 disease, but can still transmit the virus further (asymptomatic carriers). The significance of asymptomatic transmission is still very uncertain, but probably lower than from people who have symptoms.
The coronavirus can be transmitted from the patient's respiratory tract in three main ways:
- Droplet transmission: People with COVID-19 disease emit droplets and particles from their nose and mouth that contain SARS-CoV-2. The droplets / particles come in different sizes and amounts depending on the situation. The amount increases with, for example, exercising, singing and coughing / sneezing. Infection can occur when virus-containing droplets and particles come in contact with the mucosa of the eyes, nose or mouth, or if they are breathed into the respiratory tract. The significance of the various droplet sizes for transmission is still uncertain. When transmission occurs within 1-2 metres of someone who is contagious, it is called droplet transmission. Studies indicate that the risk of infection decreases rapidly with increasing distance to the contagious person, and that the risk of infection is reduced by 80 per cent if you keep a distance of one metre.
- Direct contact: Droplets / particles containing the virus from the respiratory tract land on nearby surfaces and are transmitted from there to the respiratory tract of another person. Contact transmission occurs either through direct contact with a contagious person (for example, by a hug or handshake) or indirectly via contact with other surfaces contaminated with viruses (door handles, light switches, handrails, etc.)
- Airborne transmission: Tiny virus-containing droplets / particles from the nose and mouth of an infectious person can remain suspended in the air for a long time and move over longer distances. The amount of droplets / particles and virus decreases rapidly over time and with increasing distance. To become infected, someone must be exposed to a certain amount of infectious virus. For SARS-CoV-2, this amount is unknown, but modelling studies indicate that the amount of infectious virus to which they are exposed at distances of more than 1-2 metres will seldom be sufficient to cause infection. In some situations, however, it is possible that airborne transmission can occur, and cases have been reported where this may have been the mode of transmission. This happened in small rooms with poor ventilation (Inneklima og risiko for smitte av covid-19 - Råd om ventilasjon). However, airborne transmission is considered to be significant in some medical procedures performed in the healthcare service, so-called aerosol-generating procedures. In these situations, NIPH recommends that healthcare professionals use extra protective equipment.
Which situations involve a greater risk of transmission?
It is not documented how many COVID-19 patients are infected by each mode of transmission, but droplet transmission is assumed to be the most important one.
Individual differences in how much virus and droplets a person produces have been documented. Some people can produce up to 10-100 times more droplets than others. Several studies indicate that 10–30 per cent of those infected can account for about 80 per cent of the infection, and they are often referred to as super-spreaders. Super-spreading cases can occur in situations where many have been with one or more contagious people for a long time, often indoors in rooms with limited space. Limited air volume and air circulation increases the concentration of virus-containing droplets / particles, in addition to poor ventilation with infrequent air exchange in the room. In addition, the contagious person was often been at the beginning of their disease phase, the highest amount of virus is usually present in the days around the onset of symptoms.
The virus has been detected in faeces (stools), blood and urine, but it has none been shown that anyone has been infected by contact with these bodily fluids.
- SARS-CoV-2, MERS-CoV og SARS-CoV and risk of airborne transmission – a rapid review
- Transmission of SARS-CoV-2 via contact and droplets, 1st update Transmission of SARS-CoV-2: implications for infection prevention precautions. 9. juli 2020 (WHO)
- Scientific Brief: SARS-CoV-2 and Potential Airborne Transmission (CDC)
Infection from food, water and animals
Currently, there are no known cases of infection via food produced in Norway or imported, or from water and animals. Several systematic reviews have concluded that this is an unlikely mode of transmission.
There have been some cases of transmission between animals and humans. Mink and other species in the marten family appear to be highly susceptible to infection, and both human-to-mink and mink-to-human infections have occurred in the Netherlands and Denmark. It is important that people with COVID-19 or people in quarantine do not go to work as keepers and have close contact with mink.
Infection from animals does not appear to play a role in transmission of the virus.
- Mattilsynets informasjon om covid-19 og dyr (Norwegian Food Safety Authority)
- OPINION of the French Agency for Food, Environmental and Occupational Health & Safety (systematic review from ANSES OPINION)
- ICMSF opinion on SARS-CoV-2 and its relationship to food safety (systematic review from International Comission on Microbiological Specifications for Foods)
- Questions and Answers on the 2019 Coronavirus Disease (COVID-19) (World Organisation for Animal Health)
- Mink og covid-19 (Norwegian Food Safety Authority)
In the case of swimming pools, the chlorine content of the pool water will be sufficient to inactivate coronaviruses and other viruses. However, physical contact in changing rooms and by the pool could lead to transmission as with any other close contact.
How contagious is it?
Calculations estimate that a person infected with coronavirus infects 2-3 others (2-4) whereas a person with influenza will infect 1-2 people. Probably fewer than 20 per cent of those infected with SARS-CoV-2 virus account for 80 per cent of the transmission. This indicates that the majority of confirmed cases will not transmit further, while a minority will infect many.
The number will probably be lower than 2-3 in Norway because we have a lower population density and have implemented infection control measures.
The incubation time (from infection until symptoms appear) is usually 5-6 days. Based on current figures, 98 - 99.9% of infected people develop symptoms within 10 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.
Usually, people who become ill first develop 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. Loss of the senses of smell and taste is also reported.
The course of the disease varies widely between individuals. Currently, the typical courses appear to be:
- Mild course: This applies to the majority of people who become sick. 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. As for other serious infections, different complications can arise with severe COVID-19, including lung damage, cardiovascular disease and coagulation disturbances (5-8). Some people who become seriously ill may die.
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, but vaccines are under development.
More about the symptoms of COVID-19
It appears that SARS-CoV-2 mainly infects upper and lower respiratory tract cells and causes respiratory tract infection with symptoms such as cough, fever and sore throat. Most people who get COVID-19 only develop these symptoms.
A minority enter a more severe phase with breathing difficulties and symptoms of systemic disease that are probably caused by the body's immune response to the infection. There is a good basis to assume that SARS-CoV-2 also infects the gastrointestinal tract, and related symptoms are frequently reported.
We are learning more about the symptoms of COVID-19. Much of the knowledge is based on patients admitted with severe disease. These account for about 20 per cent of all people who develop symptoms and probably do not reflect the overall clinical presentation.
The most frequently reported symptoms of COVID-19 are fever (22-83 %) and cough (25-70 %) (9). In addition, the following are frequently reported: muscle aches (7-31%), fatigue / weakness (13-20%), headaches (18-43%), altered sense of taste and smell (2-54%), runny nose (6- 28%), chills (2-15%) and sore throat (6-30%) (10-13).
These mild symptoms are often reported when people with COVID-19 are identified by screening or follow-up of close contacts. Therefore, these symptoms are probably present among all cases of COVID-19 disease that cause symptoms, but the milder symptoms may go unnoticed when a person has other, more severe symptoms.
Shortness of breath (dyspnoea) is frequently reported (15-40 %) and is an indication of severe disease that often requires hospitalisation. The proportion that develops shortness of breath appears to be small if mild cases are included in the calculation (11).
Gastrointestinal symptoms such as pain, nausea / vomiting and diarrhoea have been reported in 2-40 % of cases. In one meta-study of 4243 patients, 17.6 % of patients had gastrointestinal symptoms (14), which may be the first and, in some cases, the only obvious symptom of the disease (15, 16).
Neurological symptoms other than headache and changes in senses of taste and smell. These may include dizziness, altered mental state, ataxia and tremor. Cases of diarrhoea and haemorrhagic strokes, encephalopathy and Guillain-Barré are also linked to SARS-CoV-2 infection (15, 17, 18).
There have been no certain findings of the virus in the central nervous system, and the mechanisms behind these neurological symptoms are unclear.
In addition, symptoms have been reported for most organ systems such as the eye (e.g., conjunctivitis), skin (rash), heart (myocarditis, arrhythmias, infarction) and kidneys (acute kidney damage) associated with the disease (9, 15, 19, 20).
Coagulation disorders appear to occur frequently in seriously ill COVID-19 patients, but are also described among patients with mild disease. This may explain symptoms such as blood clots in the lungs (pulmonary embolism) and deep vein thrombosis, and also some of the neurological and cardiovascular symptoms described above. (9, 13-16, 21).
There is an increase in the number of reports of COVID-19 patients with hypoxia without dyspnoea or other symptoms of hypoxia. The clinical significance of this is currently unknown, but frequent measurement with an oximeter may be considered in COVID-19 patients at risk of a severe course (for example, in a hospital). Patients with silent hypoxemia should be assessed by a doctor for possible causes, such as pulmonary embolism.
Symptoms of COVID-19 among the elderly
High age is the most certain risk factor for severe disease and death from COVID-19.
Elderly patients often have an atypical clinical presentation with many diseases (22) and this also applies to COVID-19 (23, 24). In addition to the symptoms mentioned above, there are a number of atypical symptoms that occur among the elderly with COVID-19, such as delirium (acute onset of cognitive failure and altering emotions and behaviour), confusion (new-onset or deterioration), tendency to fall (new-onset or deterioration), lethargy and weakness (new-onset or deterioration), generally poorer function level, weight loss, decreased appetite. Elderly people with dementia have a significantly increased risk of delirium with infections. These symptoms may overshadow other and more common symptoms of infection, such as respiratory problems (24).
The reason why older people more often present with atypical symptoms may be age-related changes in the immune system, temperature regulation may be poorer, and the ability to remember and recall symptoms may be impaired. Elderly people also more often have underlying chronic conditions that can affect the clinical presentation, e.g., strokes and other neurological disorders can impair the cough reflex (25).
Therefore, COVID-19 should be considered as a differential diagnosis among the elderly, even with atypical and / or mild symptoms.
Symptoms that are particularly important to be alert for in this group are tachypnea (rapid breathing), tachycardia (rapid heartbeat), hypotension (low blood pressure) and low-grade fever (above 37.5 °C).
The assessment of elderly patients should be made by people who are familiar with the patient’s normal functional level so that changes can be detected quickly; Here, both health professionals and relatives can play a role. An early diagnosis will ensure the best possible treatment and prevent the spread of infection, especially in hospital and nursing homes.
Symptoms among children
Children appear to have a similar clinical presentation to adults, but the proportion with severe disease is much lower. Most have symptoms of colds, such as cough, fever and sore throat, which last from several days to a week.
Fever (41-48 %) and cough (39-48 %) are the two most common symptoms. A sore throat was observed among 46 % in one study. Other relatively frequently reported symptoms are diarrhoea (7-9 %), nausea / vomiting (6 %), lethargy (7.6 %), mucus and runny nose (7.6 %). Other rarer symptoms include stuffy nose, headache, abdominal pain and shortness of breath (26, 27).
Multisystemic Inflammatory Disease in Children (Kawasaki-like disease)
At the end of April 2020, British health authorities reported that an increasing number of children were admitted to intensive care with symptoms similar to Kawasaki disease. Kawasaki disease is an acute condition with inflammation of the blood vessels in different parts of the body and usually affects children under 5 years.
The condition is characterised by fever lasting for more than 5 days, rash, mucosal changes on the lips and mouth, eye inflammation without pus, swollen lymph nodes on the neck and swollen / red hands and feet. The most serious complication of Kawasaki disease is that some of the children may develop aneurisms on their coronary arteries. There is no test to confirm the disease, and the diagnosis is based on the composite clinical presentation.
- Parental information: Kawasaki(Helsebiblioteket.no)
Kawasaki disease is rare. In Norway, 10-20 children under 5 years of age are detected annually. These children are hospitalised due to fever and poor general condition. Kawasaki disease is not contagious, but is probably triggered by an infection among children with unknown genetic risk or vulnerability. The treatment consists of giving immunoglobulin, anti-inflammatory medication and treatment to relieve symptoms. The prognosis is good, and most children recover completely within 1-2 weeks.
Among children / adolescents who have had Kawasaki-like disease during the pandemic, coronavirus has been detected in some, but not in others. The average age of those who become ill is higher than that of normal Kawasaki disease; some adolescents have also become ill. The clinical presentation is different from Kawasaki in that there are more often gastrointestinal symptoms and abnormally low blood pressure. Patients have received the same treatment as for Kawasaki disease. Most of them are in recovery or are discharged from hospitals. The association with the coronavirus is uncertain, but paediatricians, NIPH, European Centre for Disease Control (ECDC) and the World Health Organization (WHO) are following the situation closely.
On 15th May 2020, the ECDC and WHO issued their definition of the condition, i.e., which combined symptoms can give suspicion of this syndrome. There is no test to confirm this Kawasaki-like disease. Both probably cause an overreaction in the immune system in connection with, or after, an infection. WHO calls the syndrome “Multisystem inflammatory syndrome in children and adolescents temporally related to COVID-19”, while ECDC calls it “Paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 infection”.
ECDC and WHO stress that COVID-19 mainly causes mild illness among children, and that it is extremely rare for children to become seriously ill. The most important advice for parents is the same as always: they should seek medical attention when a child with a fever has a poor general condition and they are concerned for their child, for whatever reason.
ECDC and WHO's assessments can be found here:
Long-term health consequences of COVID-19
COVID-19 is a new disease, and little is yet known about long-term health consequences (sequelae) after having had COVID-19. Several studies about this have been initiated both in Norway and abroad.
For most people, COVID-19 is a mild and short-lived disease. However, it has also been reported that people who had a mild course of the disease may struggle with long-term symptoms, including fatigue, headaches and difficulty breathing (28). The frequency and duration of these symptoms are unknown (29).
It is already known that people who are treated for severe respiratory failure in intensive care units due to other diseases may struggle with long-term disability after discharge from hospital, such as impaired cognitive function and impaired lung function. Since respiratory failure and long-term intensive care treatment occur during severe COVID-19 disease courses, similar sequelae could be expected (30).
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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.
Information for the general public
Information helpline for questions about coronavirus: 815 55 015 (weekdays 08-15.30)
The Norwegian Directorate of Immigration has answers to many frequently asked questions about travelling to Norway, and a helpline 23351600 that is open on weekdays from 10:00-14:00.
The Ministry of Foreign Affairs also has answers to many frequently asked questions.
If you need acute medical attention, contact your doctor. If you cannot reach your doctor, contact the emergency out-of-hours clinic on 116117. If life is in danger, call 113.