Sars-CoV-2: How contagious is the coronavirus?

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Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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People all over the world are infected with the new type of coronavirus Sars-CoV-2. How infectious is the pathogen? When can an infected person infect others and for how long? And which transmission routes are possible? Find out here about the most important facts about infection with Sars-CoV-2.

How contagious is Sars-CoV-2?

The novel coronavirus Sars-CoV-2 multiplies strongly in the throat area at the beginning of the infection. This distinguishes it from the closely related first Sars virus of the 2003 pandemic, which was only able to multiply deep in the lung tissue. The Sars-CoV-2 pathogen is therefore much more contagious.

Containing Sars-CoV-2 is more difficult than was the case with the Sars pathogen from 2002/2003. The reason: The novel coronavirus is not only passed on more easily, it is also transmitted 2.5 to 2 days before an infected person develops symptoms. That means: Before the infection is apparent.

Even infected people with few symptoms who develop no symptoms at all can infect others. In some of them, large amounts of virus were found in the throat, although they did not show any symptoms typical of corona.

You can find more information about the Covid-19 disease, the typical symptoms and the typical course of the infection here.

How long are you contagious?

How long exactly someone is contagious cannot yet be said with general validity and also depends on the course of the disease.

The following therefore currently applies:

• Seriously ill patients are no longer considered to be contagious if they have had no symptoms for at least 48 hours and no viruses were detectable in two throat swabs 24 hours apart. Those affected can then be discharged from the hospital without any further conditions.
• Sick people who have been treated in hospital and released into quarantine when they get better may not leave the quarantine before 14 days at the earliest - provided that they have had no symptoms for at least 48 hours and the attending doctor has not ordered otherwise.
• Slightly ill people who do not require inpatient treatment are not allowed to leave their home isolation until 14 days after the onset of the symptoms of the disease at the earliest - provided they have had no symptoms for at least 48 hours and the attending physician has not ordered otherwise.

Droplet infection

By far the most common way in which the Sars-CoV-2 coronavirus is transmitted is via secretion droplets: when coughing, sneezing, but also when speaking in a wet voice, droplets containing the virus are ejected from the airways. They are comparatively large and quickly sink to the ground. That is why a minimum distance of 1.5 to 2 meters from potentially infected people is so important.

If the droplets hit you on your face, the viruses can get into the body via the mucous membranes - i.e. via the mouth, nose and eyes. Simple protective masks hardly protect the wearer from this.

Contact infection

If an infected person coughs into his hand and then opens a door, he transfers the pathogen to the handle. If someone else touches this handle in a timely manner, the viruses will end up on his hand. If he then rubs his eyes or touches his nose, for example, the viruses can penetrate the body through the mucous membrane. Virus transmission is of course possible even with a handshake.

For this reason, frequent, thorough hand washing is another important preventive measure against infection.

Airborne infection?

Some researchers now assume that the virus can also be transmitted through the air. When you breathe out, the pathogen gets into the air in much smaller droplets than when you cough.

These so-called aerosols are smaller than 5 micrometers. They do not fall directly to the ground, but float in the air for a while and can, for example, be distributed in an enclosed space with the movement of air. Then they could be inhaled by other people.

It is therefore possible that the risk of infection in the open air, where the viruses spread quickly, is significantly lower than in closed rooms.There it helps to reduce the viral load in the air through frequent thorough ventilation.

Smear infections from stool?

The virus has also been detected in stool samples from corona patients. This is especially true for patients who suffered from diarrhea as part of the disease. However, it is not yet clear whether you can actually get infected through stool-contaminated objects or skin contacts. If anything, this transmission route plays a very subordinate role in the spread of the disease.

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