#6: Can vaccinations end the pandemic?

The name promises a joy of victory and a promising future, the same cannot be said about the Corona virus. For months, it has been influencing the daily lives of millions of people around the world in ways not previously thought possible. In the current episode of our podcast "Wissen, wann du willst", microbiologist Prof. Dr. Achim Kaasch talks about viruses, tests and what they can reveal about the virus, about vaccines and their mechanisms of action, but also about why it seems that living together with the Corona virus is inevitable.

Guest today

Microbiologist Prof. Achim Kaasch heads the Institute for Medical Microbiology and Hospital Hygiene at the University of Magdeburg. The physician has been successfully researching bacterial infections for years. In his lectures on the medical campus, students from the 6th semester hear essential insights into various aspects of microbiology and virology. By his own account, he has not regretted for a moment in recent months that he has made virology his profession and will continue to devote his research and teaching to these tiny but no less effective structures.


*the audio file is only available in German


The Podcast to Read

Intro voice: "Wissen, wann du wilst." The podcast about research at the University of Magdeburg.


Katharina Vorwerk: Welcome to a new edition of our science podcast. My name is Katharina Vorwerk and today's guest is Prof. Achim Kaasch, a medical doctor, microbiologist and head of the Institute for Medical Microbiology and Hospital Hygiene at the university. The setting of our conversation already reveals a lot about today's topic, because I am sitting in the press office on Uniplatz, and Prof. Kaasch is in his office at the Institute on Leipziger Straße. The culprit in this long-distance conversation is - of course, what else could it be - the coronavirus, which has been dominating our daily lives for months. Over the next few minutes, we will talk about what makes these actually simple structures so destructive, how we can combat them, and why coexistence with them nevertheless seems inevitable. Good afternoon, Professor Kaasch. I hope the line is working.

Prof. Achim Kaasch: Yes, good afternoon, I can hear you very clearly.

Vorwerk: That is great. Then, let us get started. Prof. Kaasch, at the beginning of our conversation, I would like to ask you a personal question: In the past few months, have you regretted for a brief, unguarded moment that you made virology your profession?

Kaasch: Yes, I came to virology more or less by chance by coming to Magdeburg in October 2019. Before that, I was not very involved in virology and now it is part of the institute's portfolio. Of course, as a specialist in microbiology, virology and infectious disease epidemiology, virology is part of it. Nevertheless, at many universities, this is divided into different institutes, so that not all of them have years of experience in virology. In my case, I was given this task shortly before Corona. On the one hand, that was very exciting, but on the other hand, it was of course very new and ultimately something new for everyone.

Vorwerk: That does not sound much like regret, but rather like, "there's still a little strength left.”

Kaasch: Yes, there is still a bit of strength there. On the other hand - of course, there are situations where you think to yourself: Why me? Moreover, why in this particular situation, when everything is new anyway and the plans were completely different, namely building up a research group and rebuilding an institute?

Vorwerk: I believe you. Now let us get straight to the point. Viruses are nothing more than a piece of genetic code wrapped in fat and proteins. What makes this triple combination so effective, i.e. how does this relatively simple structure achieve - from your point of view, of course - such great success?

Kaasch: The interesting thing about viruses is that they have a very simple structure and yet exploit the structures of their host. In our case, i.e. in the case of coronaviruses primarily in humans, in order to spread further. In other words, a virus consists of only a few genetic building blocks, but these are sufficient to spread efficiently. That is what characterizes a virus, which is why they are so small.

Vorwerk: In order to know who is infected with the Corona virus, we use the so-called PCR test, which was developed years ago, as the gold standard. What specifically does it actually detect, or what can we ascertain if this test is positive?

Kaasch: Perhaps we will make a short excursion here into the different test options. On the one hand, we have PCR tests as the gold standard, we have antigen tests, and we have antibody tests. These three things have to be kept apart in order to actually understand what we are talking about. At the same time, and this is yet another classification, you can divide the tests a little bit according to the duration, namely, how fast it is. That would be rapid tests versus normal tests, so to speak. Now maybe first to the PCR test. In the PCR test, we detect ribonucleic acid, which is the genome of the viruses, and thus we can, very sensitively, detect the viral genome from a sample.

Vorwerk: A genome is, quick interjection here, what?

Kaasch: A genome is what DNA is for humans, in the case of the corona virus; it is RNA, i.e. ribonucleic acid. And that corresponds to this genome, so to speak. To detect this genome, you first convert this ribonucleic acid strand into DNA, and then you use the polymerase chain reaction to amplify this DNA. If you now get a product, that is, the amplification has worked, and then you have proven that there is a virus in this sample. Depending on how quickly this amplification works, you can also deduce how much virus was probably in this sample. Because the faster you see a product, the more virus must have been in the sample beforehand.

Vorwerk: You also spoke earlier, so now it was about the PCR test, you also spoke about the antigen rapid test and antibody tests. I do not think we need to discuss these in detail here, but the important thing would be: Do I get identical information from all these tests?

Kaasch: Perhaps very briefly about the antigen test. In the antigen test, you are not detecting the virus genome, but the proteins that are present in the virus. And in the antibody test, you detect the body's immune response to the virus. You can only detect that after a few days or weeks. Do you get the same information from that? No, you do not. The antigen test, i.e. where I detect the viral protein, this test is much later than a PCR test. We can say: It is not as sensitive. With the antibody test, it takes two to three weeks before the test is positive. Moreover, according to our experience, it only works for half of the people who have had an infection. Therefore, with this test, you cannot say for sure if you had an infection. Conversely, if the test is positive, then you can assume that you have had an infection.

Vorwerk: That all sounds relatively complex and involved. I would now like to turn to a rather controversial topic, namely vaccination. From a virological point of view - what weapons does a successful vaccine actually use to counter this virus? Do viruses have something like an Achilles' heel, in the figurative sense?

Kaasch: Vaccines work by triggering an immune response in the body, against the virus. This immune reaction trains the body to act more quickly in an emergency, when there is an infection.

Vorwerk: So why do you think that the corona vaccines were developed so quickly, sort of in many places around the world at the same time?

Kaasch: The vaccines that were developed most rapidly are the RNA vaccines. In principle, they are based on a new mechanism of action. Namely, RNA is injected and this RNA is converted into proteins, and these proteins are recognized.

Vorwerk: We have that at Biontech and at Moderna, correct?

Kaasch: Exactly, those are these two vaccine variants and there will probably be a third one coming from Germany in the Fall, from Curevac. And these vaccines are apparently new. But if you look at the history of development, you see that ten, fifteen years ago and ultimately longer, the foundations were laid for these vaccines to be effective. And also two, three years ago, there was crucial work that was necessary for this vaccine, for coronaviruses. This was born out of the need to find a vaccine against the Sars I virus, which was not pursued further or was not brought to market maturity because the Sars I pandemic failed to materialize.

Vorwerk: How do you estimate the current discussion about the various assessment of Biontech, Moderna and Astrazeneca?

Kaasch: So I'm curious to see what the data will actually show in the future. That is how I see it now, but I will also let myself be corrected by the data, possibly in the future. Currently, I see that the different study designs are responsible for the different assessments regarding the performance of the vaccines. What does that mean? It means that with the RNA vaccines, in order to assess the efficacy of the vaccines, we only looked at infections where symptoms occurred. With the active ingredient from Astrazeneca, we also looked primarily at this: Are there asymptomatic infections? These differences could also lead to different estimates of efficacy for mild infections. For severe infections, all vaccines seem to be relatively good, or even very good.

Vorwerk: We have managed to develop a vaccine against the pathogens of polio, measles and now, also in part, for Corona. Why can we not do the same for influenza?

Kaasch: In influenza, two phenomena make vaccine development difficult, or make sustained vaccine development difficult. After all, there is a new vaccine or vaccine combination every year, and these two mechanisms are antigenic shift and antigenic drift. Antigen shift means that the virus can change by picking up genetic code from related viruses. That is how, for example, avian flu or swine flu are created. There, parts of the virus are simply exchanged. Antigenic drift, on the other hand, is something that we are now also observing in Corona, namely viral mutations that produce small adaptations. That is the second reason why vaccines do not work as well as they did the year before.

Vorwerk: So we are learning: Vaccinations do not make the viruses disappear. Therefore, it seems that we will have to live with the coronavirus in the future.

Kaasch: I assume that we will still have the coronavirus circulating for many years in the future. This is a very normal process, when new viruses enter a population, and then there is infestation but still. We call this fixation in a population, which means the viruses will be there permanently. We know this from the so-called endemic coronaviruses, which have been circulating in our population for many years and are detected in us in small quantities every year.

Vorwerk: We have not seen this in other epidemics - or I have not noticed it yet - that virologists are constantly on the front line, I would say. They have been a permanent fixture in the media for months and have stood for evidence-based solutions to problems, but for many people, the picture is anything but clear. There is Team Drosten, Team Streeck, there is Storymachine and Heinsberg. Do these publicly controversial discussions really create trust in science?

Kaasch: That is a very difficult question. In addition, when you mention Storymachine and Heinsberg: Those discussions were somewhat irritating, i.e., from a scientific point of view, very jarring discussions, where it was not always about the content. Now, there is also a very strong polarization of opinion on many different topics. On the one hand, it is good that discussions can and must be held in democracy, but on the other hand, of course, they are not always held with the necessary expertise.

Vorwerk: In the end, that is a difficulty we have to deal with. It has been brought up again and again: Do we need a pandemic council? Do we need a committee at a state or federal level in order to streamline the discussion? I think that could also be a way of limiting the cacophony that ultimately exists.

We come to the end of our conversation where we understood that viruses are a kind of assailant that invade cells through nasty deception and force them to make copies of themselves. That all sounds rather unsympathetic. What fascinates you about viruses, though? Why will you continue to research them with such enthusiasm?


Kaasch: I would like to give you a somewhat surprising answer. For me, it's nice to look at a system that potentially doesn't necessarily affect you, but that can nevertheless influence people very strongly. In the case of viruses - as we are now also seeing with the virus mutations - and how viruses spread in a population, that is certainly a very exciting research topic. Moreover, the question: How can this spread be efficiently prevented? And with the coronavirus, we will now have a major task in understanding this as a model for limiting future pandemics.

Vorwerk: With this statement, our podcast comes to an end today and I would like to thank you very much, Prof. Kaasch, for your time. For now, I wish for all of us, a corona-free future and if you have any questions or topics that interest you, just write to us at Until then, stay healthy and take care! See you at our next edition of the podcast in May.


Outro voice: "Wissen, wann du wilst." The podcast about research at the University of Magdeburg.

Last Modification: 29.04.2021 - Contact Person: Webmaster