Protective measures against the coronavirus: Why? And why do they keep changing?

Dear Colleagues,
dear Students,

I hope you all had a relaxing summer and return with renewed energy!

Unfortunately, the SARS-CoV-2 (COVID-19) virus will continue to dominate our daily lives for a long time to come. This will not change until an effective and safe vaccine and treatments are available. For this reason, we will only be able to offer limited face-to-face courses at the University in the coming semester and will issue policies that will need to be adjusted regularly. Many of you will find this irritating. I can well understand that, especially since the reasoning behind these rules is not always clear to everyone. Therefore, I would like to explain which findings form the basis of our measures (many thanks to Professor Simone Scheithauer from the UMG for critically reviewing this text).

The aim of all protective measures is to slow down the further spread of the virus in order to keep the infection chains manageable and not to overload our intensive care capacities This requires predicting the spread of the virus under various conditions, which can be done using recently developed mathematical models. Assumptions must be made about the proportion of people who are infected in the population at any time, and the risk of infection must be estimated for each event where people come together.

The most important goal of our actions as University management is the quantitative assessment of the residual risk – absolute safety cannot be guaranteed. Let us assume that one in a thousand people is infected with SARS-CoV-2 and you attend a seminar with 20 people. Then the probability that one of these 20 persons is infected is low – it is just under 2%. If we assume that despite the low prevalence there is one person carrying the virus among the participants of the seminar, this does not necessarily lead to a transmission, especially if you are careful and take preventive measures. In estimating the residual risk, therefore, two assumptions have to be made: (1) What is the probability that one or more people carrying the infection will attend the event? And (2) if this is the case, what is the probability that this person(s) will pass on the infection to others?

This is the reason why it is so difficult to establish consistent and long-term rules for events such as classroom teaching and practicals. If we permit a few seminars under the conditions mentioned above, the risk is acceptable. However, if there are hundreds of them, that is no longer the case.

While the proportion of people carrying the infection in the total population can now be better estimated than just a few months ago, it is still difficult to determine the actual risk of infection at events. We need to evaluate each type of event separately. This is helped by the fact that much has been learned in recent months about the spread of SARS-CoV-2 and the ways the virus is passed on.

Infection with SARS-CoV-2 occurs primarily via the air we breathe. When we breathe out, and even more so when we speak, sing or even exercise, we emit countless microscopic droplets, which in the case of someone carrying the infection can contain many virus particles. The larger of these droplets do not spread beyond one to two meters, but fall to the ground – hence the distancing rules. With smaller and lighter exhaled droplets that do not fall to the ground so quickly, a large proportion of the water evaporates within seconds to minutes. As a result, an aerosol is formed in which residual water initially remains bound in a mucous coat that forms around the virus particles. These aerosols can remain suspended in the air for a long time. It has now been proven that such aerosols can also be infectious. You have probably all heard about choir rehearsals where the distancing guidelines were followed, nonetheless a single infected person passed it on to many other people. At some point, the viruses in the aerosol particles are damaged – either by UV radiation (from the sun) or by further drying out – and their infectivity decreases. How long this takes depends on the conditions: outside, in the sun and when it is warm and dry, it is probably only seconds, but at low temperatures and high humidity, such aerosols can remain infectious for hours.

These findings explain the protective measures aimed at reducing the risk of spreading. In general, the following rule from the Robert Koch Institute applies, known as AHA: Abstand (distance) of 1.5 meters; Hygiene (cough only in the crook of your arm, wash your hands regularly with soap, avoid touching your eyes, nose and mouth); and Alltagsmasken (everyday masks). Please find below, further explanations about the protective measures at our University:

Face masks: masks that cover the mouth and nose, even simple cloth masks, retain larger droplets well when exhaled. This means that they offer less protection to the wearer than to other people – in case the wearer is carrying the virus unknowingly. Their protective effect has now been proven beyond doubt. Therefore, it is very useful to wear masks in a room with several people during an exam, even if it is annoying. Ideally, masks should also be worn when speaking, because the amount of droplets emitted increases. This is of course quite impractical. But in a meeting or seminar where many people are speaking and no masks are worn, there is a much higher risk of spreading the virus than when only one person is speaking and the others are listening, especially when masks are worn.
Events in closed rooms: since aerosols accumulate in the air in closed rooms over time, the applicable distancing rules should not make us feel safe – especially during longer events (eg committee meetings, discussion groups). What helps more is frequent airing (high rates of air exchange), but this is not possible in every situation. This also applies if you meet privately. Insufficient air exchange also explains why you should avoid elevators if possible – the volume of the space is very small and aerosols remain in the air even if an infected person has already left. Events should therefore, if possible, only take place in rooms that can be sufficiently ventilated.
Establishing separate teams: if you have to form small teams for an internship or excursion, the teams should not have any contact with each other. If one person in a team is infected, the risk of the other team members being infected is obviously high. However, the other teams are not infected – the infection remains limited and there is no „superspreader event“. Here it becomes clear that it is not primarily a matter of protecting individuals, but of preventing the spread of the virus. At the Presidential Board, we separated the teams of the three full-time members right at the beginning of the crisis – if one team is infected (which, thank God, has not happened yet), the other two teams are not affected and remain able to work.
Regular voluntary screening for SARS-CoV-2: a final measure, which we are currently working hard to implement together with the UMG and our Campus partners, is the comprehensive and regular SARS-CoV-2 testing of all University staff and students who agree to be tested. This will enable us to control the initial risk of an infectious person being present at an event much better. As soon as the tests are available and a sufficiently high proportion of people at the University have agreed to take a test voluntarily, we at the University will have much more reassurance about events with physical presence that we have planned for the winter semester. I will inform you separately about this.

I hope that these explanations will help you not only to understand our actions as University management, but also to better assess the risks for yourself and to behave, not only in the University, but also in your private life in such a way that you and others avoid infection if possible.

Please take care of yourself and others. If we all adhere to the rules and take care of each other, we will hopefully get through the crisis without harm.

With kind regards,

Professor Reinhard Jahn, President

Please find more information on the University’s rules and regulations regarding the coronavirus