Experts answerHeidelberg Virologists on the Coronavirus/COVID-19

19 March 2020

Prof. Dr Hans-Georg Kräusslich and PD Dr Nico T. Mutters answer questions about coronavirus/COVID-19. Prof. Kräusslich is spokesperson of the Centre of Infectious Diseases at the Heidelberg University Hospital and director of its virology division. Dr Mutters heads the centre's section for hospital and environmental hygiene.

Kräusslich und Mutters

How is SARS-CoV-2 transmitted?

The main way of catching coronavirus SARS-CoV-2 is from respiratory droplets, for example from coughing or sneezing, but also through what are called smear infections. Even infected persons who only have a mild case of the disease or are largely asymptomatic can pass on the virus. This can happen in a private or work context but also at large-scale events.

How great is the danger of infection?

You can only be infected if you come into close contact with acutely infected persons. At present the number of infected persons is still relatively small. However, there is great diversity at the regional level and the numbers of infected persons are clearly rising so that it cannot be foreseen how this will turn out in the future. Consequently the risk at a given point in time needs to be constantly reassessed. Fundamentally we can say that the greater the number of those who are infected, the greater the number of those falling seriously ill will be. In view of the current distinct rise in infected persons in Germany, it is paramount to once again highlight the rules for everyday behaviour set out below, including social distancing. Every citizen has a responsibility towards people at risk in the community. Through appropriate behaviour in daily life, one can considerably slow down the spread of the virus and thereby make a contribution to protecting people for whom the risk may prove fatal.

How high is the danger related to an infection?

The vast majority of all infections (approx. 80 percent) run their course with mild symptoms, comparable to a cold. About 15 percent of infected persons undergo more serious symptoms during the COVID-19 disease, with difficulty breathing. About one out of 20 infected persons develops full-blown pneumonia, that is a serious lung inflammation. There are varying estimates regarding the frequency of deaths caused by SARS-CoV-2, so that a final answer to this question cannot be given at the moment. Elderly people and people with underlying conditions are particularly at risk. Probably the mortality rate after infection with SARS-CoV-2 lies somewhat higher than with influenza, although this too fluctuates from year to year.

What is the intended effect of the precautionary measures currently being taken, such as suspending all lectures and classes, closing schools and cancelling events? What is the purpose of these actions?

When considerable numbers of people gather in a comparatively small space, as is the case in schools, universities, stadiums and cultural institutions, already a single infected person can lead to a large number of new infections. So all these precautionary measures have the purpose of keeping the number of people infected as small as possible and hampering the spread of the virus.

Individuals have been advised to cut back on social activities and restrict social contacts as far as possible: What exactly does that mean?

The transmission takes place through close contact with infected persons. Consequently the spread of the virus is slowed down by reducing close contacts with other people. This reduces not only our own risk of infection but also the risk for the population as a whole. Therefore, everyone is recommended to avoid private celebrations, group meet-ups and similar occasions, as far as possible.

Why are people so worried about coronavirus SARS-CoV-2?

Firstly, we are currently seeing how fast the virus is spreading worldwide and also in Germany and has also led to fatal syndromes. This rapid spread means that many people are falling ill in a short time, which may put excessive strain on the health system. In addition Coronavirus SARS-CoV-2 is probably causing particularly great concern because it is a new virus that we are not familiar with and which seems even more threatening for that reason.

Who should be tested, and when?

At present we recommend testing people with the relevant symptoms who have either had contact with infected persons or have returned from a region with a large outbreak of SARS-CoV-2 infections. Testing is not recommended for people without symptoms since the virus is mostly not yet detectable in the very early phase.

What can individuals, in general, do to protect themselves and others?

They can take the following steps to reduce the risk of infection:

  • Air any rooms used for events, offices, lecture halls etc., for example by opening the window.
  • Wash and disinfect your hands; as far as possible, refrain from shaking hands. 
  • Apply general rules for cough and cold hygiene (cough/sneeze into your elbow, dispose of your paper handkerchief immediately after use, and wash or disinfect your hands)
  • Generally keep your distance
  • Limit social contacts (social distancing)

What recommendations are there for staff and students?

Basically every individual should carefully observe the listed rules for good hygiene and at the same time, through limiting social contacts (social distancing), contribute to preventing infections in the private, professional and public sphere. One way of making a contribution to this is also refraining from travel, if it is not absolutely essential. If staff or students develop relevant symptoms after having been in a risk area or having unprotected contact with a patient who has been tested positively for SARS-CoV-2, they should obtain specialist medical advice from home and coordinate future procedure accordingly. People are urgently advised against turning up at a medical practice or an emergency room without a prior arrangement. The district health authority has set up a telephone hotline for this purpose.