Monday, 23 March 2020

Leading German virologist Prof. Dr. Christian Drosten goes viral (intro & part 18)

Every workday German public radio has an interview with [[Prof. Dr. Christian Drosten]]. In the 50s every family would have sat around their radio receiver and listened with red ears. At least my impression is that nearly everyone listens.

Germany's newspaper for academics called him "Germany's de facto explainer for the current outbreak". Christian Drosten is leader of the virology department of one of the most prestigious hospitals in the world, Berlin's Charité university hospital. He developed the first diagnostic test, which is called the WHO test in Anglo-America, and was shipped to 150 countries.

I guess our university press office would like me to mention that before he went to Berlin Drosten headed the Institute of Virology here at the University Hospital in Bonn.

Because these podcasts are appreciated so much, I thought it would be valuable to translate them into English. The virology is universal, the epidemiology and counter measures will depend on the local circumstances. The latter can be interesting for foreigners in Germany and for inspiration for other countries, so I will also translate such parts.

In one podcast Drosten discussed an article on the influence of closing schools on the Spanish Flu in American cities, where it worked. Some German newspaper made this into a story: "Drosten recommends closing schools", while he also talked about the societal differences between Germany now and America a century ago. As a climate scientist, I will not pretend to know the science good enough to contribute, but I do understand it better than political journalists and that I can promise not to leave out such important context.

If you know German you can find all podcasts with transcripts on the webpage of NDR. The topics of one podcast are all over the map, whatever is current. This podcast science journalist Korinna Hennig asked the questions.

Air pollution

The first interesting question was about the role of air pollution. Drosten answers:
"Yes, there is certainly some speculation about it. But what is perhaps even more important, if you want to talk about something like that, is of course smoking. And we don't even know what the reason for this surplus of male patients is. What is clear, however, is that in China it is mainly men who smoke. And of course it is also clear that in the generation of patients who are now particularly at risk, it is above all men who have smoked a lot throughout their lives. And of course, risk factors for cardiovascular disease are also more prevalent among men in this age group. And I think that all of this plays a role in this pattern. ... It is certainly always a good time to quit smoking, but now is probably a particularly good time."
That sounds like an interesting idea worth pursuing in more detail.

Data quality, comparability

Another interesting question was why "there been so many fewer deaths from SARS-CoV-2 in Germany than in other countries?"

The main explanation is that in other countries far fewer mild cases are recorded because less testing is done and this simply distorts the statistics. "We actually test much more than other countries." He does not expect that these differences between countries will converge when later more people will die in Germany. One reason is that soon the epidemic spreads to much that testing will no longer be able to keep up, even in Germany. Then reporting will change from confirmed cases to suspected cases.

Also data on hospital admissions is hard to compare between countries and even regions:
"There are still hospital admissions because of a diagnosis, with the intention to be rather safe and to admit patients to the hospital in order to isolate them. And in other regions there are already many cases and there one will be rather hesitant about admitting patients who are otherwise healthy."


Drosten and his team work on sequencing the genome of the virus. This used to be to study how the virus is spreading. The main road on which the virus travels to Germany used to be holidaymakers returning from Italy, but this is now changing and soon everything will be very mixed. The next task would be to study whether the virus is changing:
"The real issue then is whether the virus remains stable. And for that you simply have to continue sequencing viruses at a certain frequency. And always look, is the genome still complete? Have mutations crept in at important places? And do these mutations have any significance? In other words, then one has to switch over to the targeted examination of these viruses in the laboratory."


If someone was ill and acquired immunity Drosten estimates that they can no longer carry the disease to others. To be sure large clinical studies are needed, which will be done later. To infect others the virus would have actively replicate in the throat.
"we know from a monkey experiment that once an infection has been overcome, one million infectious viruses can be introduced directly into the trachea of these monkeys and nothing happens. And that is already a very high level of challenge infection, as we call it in such a study. Now, of course, you have to say that these are not people, these are monkeys. Humans can be slightly different in detail. But there are other indications that suggest that we should have a very good immune response. For example, we know that over a long period of time, even in patients who say they have hardly noticed their infection, the virus not only replicates a little bit in the throat, but to a considerable extent in the lungs. And we should then be able to assume that a strong immune response is triggered."

Summer time

Korinna Hennig asked what the biological explanation is for the expectation that higher summer temperatures cannot contain the virus.

Christian Drosten:
"There will certainly be a small effect. A biological explanation, that is, it is just that one can see how endemic viruses decrease in frequency through the temperature effect. By endemic I mean those viruses that occur widely in the population. And these viruses have two problems when it gets warm. First, they have a permanent problem, namely there is population immunity. Then on top of that comes the second problem, let's say of the summer, in other words all the effects that this brings with it. Social distance outside and UV light, heat, dryness, so these things are not good for virus transmission, not conducive. And when that comes together with population immunity, then there is a stop to virus transmission in viruses like influenza. And now you can just look at influenza, for example, an endemic virus, to what extent is that stopped? And then you can compare a pandemic virus with it. To what extent will it be stopped? And it will not be stopped very much, but it will be stopped a bit. This comparative calculation can also be made for coronaviruses, and a study to which I referred before made this comparison. That's what was done there. And the estimate is that there will be a slight slowdown. The estimate is that half a unit of [the basic reproduction value] R0 can be subtracted. ... But at the same time, unfortunately, the estimate that the R0 value won't go below one due to this summer effect alone, that you have to do other things as well."


The podcast ended with a more political question about the effectiveness of curfews. This question is hard to answer because we do not have data on this yet and you cannot study it in isolation: 
"It's all relatively difficult to say, because the curfew itself is one of several measures that are applied in addition to the non-pharmaceutical interventions. There is also something like closing schools, tracing of infected persons and isolation of infected persons at home. Then there is the quarantine of the environment, in the simplest case, for example, the family at home for 14 days. But also the identification of contacts and their isolation at home for 14 days. All these measures come together. And now it is relatively difficult to say, if you add something on top of this, such as a curfew, what difference does it make? There is no data at all for this, either in Germany or elsewhere in other studies, in modelling studies."
Speaking more as a private person he later ads:
"I am not necessarily someone who says that we need an immediate curfew. Especially under the impression that I have that a great many people are now taking this more and more seriously and are also thinking about it, and are staying at home of their own accord. I do think that perhaps we should allow a little more time."
The Sunday after this interview on Friday, the German federal government and the state governments agreed on strong limitations on the freedom of movement.

I hope this English summary is useful. If people enjoy it I am happy to do this for future podcasts are well.

Other podcasts

Part 28: Corona Virus Update: exit strategy, masks, aerosols, loss of smell and taste.

Part 27: Corona Virus Update: tracking infections by App and do go outside

Part 26: Corona Virus Update on Vaccines: clinical trials, various types, for whom and when.

Part 23: Corona Virus Update: need for speed in funding and publication, virus arrival, from pandemic to endemic

Part 22: Corona Virus Update: scientific studies on cures for COVID-19.

Part 21: Corona Virus Update: tests, tests, tests and how they work.

Part 20: Corona Virus Update: Case-tracking teams, slowdown in Germany, infectiousness.

Part 19: Corona Virus Update with Christian Drosten: going outside, face masks, children and media troubles.

Related reading

Translated interview published today (the 21st of March): "We Have To Bring Down the Number of Cases Now. Otherwise We Won't Be Able To Handle It" Published in Die Zeit, the German newspaper for academics. (I had some trouble reading it the first months I was in Germany due to their posh language, but the information is high quality. In German the verb comes at the end of a sentence, in a "well written" sentence that is the moment you understand the sentence. In the "best" Die Zeit articles they do the same for paragraphs and articles. Only after reading the last sentence do you understand the paragraph and only after reading the last paragraph do you understand the article.)

LA Times: Germany’s extensive medical network apparently helped in early stage of coronavirus. The article is actually about all the policy differences with respect to healthcare and the economy that makes handling the situation much easier in Germany. Not mentioned is that the number of infections in Germany is one of the highest in the world, Germany is big, Germans like holiday in Italy and while people still complain did a lot of testing compared to other countries.


  1. I have finally found a (tenuous) reason to think it fortunate that Trump is President: if Obama had to issue a lockdown order the Trump Base would be out with their AR15s fighting the "guvmint" in the streets.

  2. You could be right, even under Trump "Liberty" university is opening again to spread the virus far and wide, while business leaders and GOP politicians want people to work and get ill. On the other hand, with less misinformation from the president people might have had a more realistic view of the problem.

    Obama he would have ordered face masks weeks ago, like the German government. I am so happy to live in Germany at the moment. Both the government and most people behave rationally and disciplined.

    If it were handled well, lockdown might not even have been necessary. Europe had bad luck with an unnoticed outbreak in the holiday regions of Italy and then all holiday makers coming back home. Earlier we had a small outbreak in Germany and were able to contain it. In South Korea people voluntarily stayed at home more and the government searched for infected people very effectively. We will have to see, but up to now they have avoided a lockdown.

  3. It seems I underestimated both the stupidity and the viciousness of the Trump Base:

  4. It is domestic terrorism and by far the most dangerous and damaging to society. Just recently White Supremacists planned to use the virus taken from sick members for bioterrorism against Jews and the police. That is at best one day of news. If any other group would do bioterrorism against the police, the US media would not shut up about it for over a month, but the far-right has the same sponsors as Congress and the mass media.


Comments are welcome, but comments without arguments may be deleted. Please try to remain on topic. (See also moderation page.)

I read every comment before publishing it. Spam comments are useless.

This comment box can be stretched for more space.