Scientists and health authorities assume that coronaviruses are primarily passed on through a droplet and contact infection – i.e. through direct coughing or physical contact with a sick person. Pure airborne transmission has not been proven so far.
In contrast to the known SARS infection, SARS-CoV-2 initially succeeds in a strong, active increase in the throat area. This makes contagion much faster.
Easier to transfer than expected
“It has become clear in the past few days that the virus is more easily transmitted than was thought at the start of the outbreak. This is shown by the case numbers, but also by the scientific publications on the calculation of the basic reproduction rate. It is about as high as that of the SARS corona virus from 2003 ″, says Prof. Lars Schaade, Vice President and Head of the Center for Biological Hazards and Special Pathogens from the Robert Koch Institute.
Based on this basic reproduction rate R0, researchers are currently trying to determine how the epidemic could develop. It indicates the number of people infected on average by an infected person. A value between 2.4 and 3.3 is currently assumed.
Contagious without symptoms?
It is currently believed that infected people who do not yet have any symptoms can transmit the virus. An incubation period of up to 14 days is currently assumed. This is an important factor in assessing how easily a disease can spread. Viruses become particularly dangerous if they migrate very quickly from person to person.
It is also believed that many people have become infected without ever showing symptoms.
How long do you stay contagious?
Of course, an infected person can also spread the virus if the symptoms have appeared. However, there is hardly any data on the point at which such contagiousness exists after the onset of the disease. Reproductive viruses were detected in a preliminary study in the throat up to four days after the onset of symptoms and in the sputum up to eight days after the onset of symptoms.
In various studies, components of the virus were detected in the patient’s airways up to 18 days after the onset of the disease. It is not known whether these viruses were still capable of replication and were therefore contagious. The number of viruses is also decisive.
Transmission over surfaces?
Preliminary work shows that the new corona virus can survive up to 72 hours on surfaces such as plastic or stainless steel. The number of viruses and their infectivity is likely to decrease rapidly after around eight hours.
A possible smear infection is not excluded, but has not yet been proven. Likewise, there is still no confirmed case in which people have become infected, for example, from eating contaminated food or from imported toys.