What is it about the “image” criticism of Christian Drosten

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What is it about the


The “Bild” newspaper accuses Christian Drosten of “questionable methods”, but the researchers cited in the article distance themselves from the paper. Why criticism of the study is still legitimate. The overview.



© Yiu Yu Hoi / d3sign / Getty Images



Just a few months ago, researchers remained among themselves on science platforms. However, when it comes to Corona, laypersons and journalists are also reading along. However, because the internal science discussion and the public debate function completely differently, a supposed scholarly dispute quickly becomes from a professional perspective.

This explains the discussion between the “Bild” newspaper and Christian Drosten, which was particularly lively on Twitter after the tabloid a controversial article published by the Berlin Charité virologist.

“Drosten study on infectious children grossly wrong. How long has the star virologist known about it?” Headlined the “Picture” on their website on Monday evening. Before the publication, Drosten had published a request from the newspaper, giving him an hour to respond to peer reviews and critical questions from the newspaper. “I have better things to do,” Drosten wrote.

What is it about the criticism?

A research team led by the Berlin virologist had submitted a study at the end of April, according to the children infected with the Sars-CoV-2 coronavirus, as well could be contagious like adults. The study attracted great attention and seemed to confirm the decision to keep kindergartens and schools better closed.

In the past few weeks, several statisticians have criticized the structure of the study (here, here and here.) The “picture” quoted excerpts from the technical articles without having previously spoken to the scientists. These have now distanced themselves from reporting. “I don’t want to be part of a campaign,” said Economist Jörg Stoye the SPIEGELwho teaches statistics at Cornell University in Ithaca, USA.

The research team around Drosten loaded the first study results on a so-called Preprint server highas soon as they were presented to you. Typically, scientists would wait until independent researchers have reviewed the results and published them in journals before publication.

But be in the corona crisis Research results shared as quickly as possible. On the science server medRxiv alone, 50 publications and more are uploaded per day – and get attention. This also applies to other researchers worldwide, who are now examining the research results as a kind of swarm intelligence. There is always criticism. This also applies to the study on infectiousness in children.

The sticking point: the researchers had examined the viral load in different age groups. The value indicates how many viruses are in a human’s sample and determines how contagious someone is likely to be. Because if there is a particularly large number of viruses in the throat of a person, the chance that they get into the body of another increases. If the viral load in children was significantly lower than in adults, this could mean that they are less contagious. However, the researchers around Drosten found no evidence that infected children carry fewer viruses than adults. “Children could be as infectious as adults,” the scientists concluded.

“The pre-print should be withdrawn”

But that is not exactly what the data give, even if the statement is vague, statisticians criticize. “The analysis is inappropriate,” writes well-known data analyst David Spiegelhalter on Twitter. The reason: In their conclusion, the researchers rely on statistical methods that were not suitable for the type of data. “The pre-print should be withdrawn,” says Spiegelhalter. Other statistical tests that indicated a different virus load in the age groups were not included in the evaluation. The mean viral load in kindergarten children was up to 86 percent lower than in adults.

So is the study worthless? The criticism is directed primarily against the statistical methods that have been used. The statisticians cannot say what impact this has on medical significance, as they also write in their specialist articles. You are a statistician, not a virologist.

It is still not clear what role children play in the current pandemic. Initial study results contradict each other significantly or were not statistically significant:

  • So a child in France who carried the virus had apparently no one is infected. Tests from 172 contacts were negative.

  • Data from Iceland suggest that daycare centers are not a driver of the pandemic. Meetings with more than 20 people are prohibited there, but schools and kindergartens remain largely open. Nevertheless, there are only a few known infections.

  • Show data from China opposed to the fact that children could be infected with the coronavirus as often as adults. A total of 11 children out of 148 tested contact persons under the age of 10 were infected. Their infection rate was about as high as that of adults. The assumption is based on the data from only eleven children.

Such discrepancies can hardly be borne by the public, especially in the corona crisis. However, in science they are completely normal. (Read more about this You here.) It is common among researchers to write their own contribution if there is cause for criticism and to state in factual language where the error lies. This can seem harsh to laypeople. “The current” Bild “reporting scandalizes a process that is completely normal in science. I’m very unhappy about that,” said statistician Dominik Liebl, who is also listed by the “Bild” as a critic of the Drosten study. He had no contact with the “picture”.

Did the study really ensure that daycare centers and schools are closed?

In the current episode of his podcast with the NDR, Drosten concedes for the study to have used relatively crude statistical methods. According to the researcher, one could criticize these statistics “quite rightly”, because with better statistical tools one might have found other differences.

The conclusion that children have as much virus in the throat as adults is justified. The research group checked the data again. In doing so, they noticed a statistical bias: in the early phase of the pandemic, samples from children were analyzed, who were infected but had hardly any symptoms. With them, the viral load in the throat is high. In the later phase, however, the smears came from children who were seriously ill and were treated in the clinic. In the latter group, the viral load in the throat had already dropped again.

“If we analyze this separately,” said Drosten, “it is very clear that the children have the same virus concentration as the other age groups, so there is nothing to criticize.” Whether the other researchers see it that way will be seen when the new analysis is published. That would also not be an attack or a flaw, but a scientific discussion.

Even if it should be shown that the viral load in children is lower than in adults, it could still be enough to infect others. And: Children will find it much more difficult to adhere to distance rules.

Researchers do not believe that the research team around Drosten could have deliberately manipulated the evaluation, as the “image” suggests. When the study was published, schools and daycare centers were long closed. Some states had even partially reopened their schools before the results were published. Drosten had also recently opted for the reopening of Schools and day care centers.

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