Brno doctor Jan Blatný has only been the new captain of the fight against the coronavirus epidemic for a day. “He is coming in a very difficult situation for our whole country, yet he has the courage and energy to go for it,” said Prime Minister Andrej Babiš (YES) after his appointment as Minister of Health.
He also stated that Blatný is already “well oriented” in the issue. The renowned hematologist, who replaced the epidemiologist Roman Prymula at the head of the Ministry of Health after 39 days, but spoke to the deputies on Friday about the important reproductive number R and his calculations did not correspond to how it actually works.
“If we have 1000 infected, the reproductive number will be 1.5, then the number will increase to 1500. So only by 500. If we have a million infected and the reproductive number is only 1.1, the increase will be 100 thousand. That is the problem we are facing now, “Blatný said in the Chamber.
But this is not true. The number R indicates the expected number of people among whom one already infected person is able to spread the infection. Pokud Blatný speaks of a thousand infected and reproductive numbers 1.5, the number of patients must be multiplied by 1.5. This would increase 1,500, not 500, as the Minister of Health said.
He made the same calculation error in the second example. With one million infected and a reproductive number of 1.1, patients could infect another million and 100,000 people, not just 100,000.
“The reproduction number says how many newly infected people on average per one already infected person. R = 1 means that one infected person infects another and only when (if) R reaches the value 2, for example, one infected person infects two more people, “describes the operation of the number R in his professional article Tereza Bártlová from the Faculty of Mathematics and Physics, Charles University.
He proved that Blatný did not argue at the press conference on the development of the epidemic, where he repeated the bad calculation after a few hours.
Although reproductive experts work with this interpretation, this does not mean that one infected person will infect in all circumstances the number of people that the R number just assumes. This is only an average value. It can happen that one infected person does not infect anyone, another can infect, for example, eight people.
According to the head of the Institute of Health Information and Statistics (ÚZIS) Ladislav Dušek, the reproduction number in the Czech Republic fell to 1.13 (read more here).
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