The virus is becoming less dangerous and is now far less lethal than a few weeks ago. With these statements, Alberto Zangrillo, head of the intensive care unit at San Raffaele Hospital in Milan, sparked heated discussions in Italy over the weekend. International infectiologists and the World Health Organization (WHO) have now also criticized the professor for his statements.
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WHO epidemiologist Maria Van Kerkhove said in a virtual press conference on Monday that there was no data available to show that the novel coronavirus had changed significantly. “Neither the transferability of the virus nor the severity of the disease has changed,” said Van Kerkhove. And WHO expert Michael Ryan said: “We have to be particularly careful not to give the impression that the virus has suddenly decided on its own to make you less sick. This is not the case at all.”
Viruses mutate – Sars-CoV-2 too?
Zangrillo told Rai 3 on Sunday: “In the throat swabs of the past ten days, the viral load has been negligible compared to a month or two ago.” The virus no longer exists clinically, says Zangrillo, who is also known to Italians because he treated former Prime Minister Silvio Berlusconi.
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The observations could either be due to other characteristics of the virus that have not yet been discovered, Zangrillo said, or other characteristics of the infected. “The interaction between the virus and the host has definitely changed,” the doctor told Reuters on Monday.
In fact, it is not uncommon for viruses to mutate and adapt to their environment. This is known, for example, from HIV or influenza viruses. With Sars-CoV-2, however, scientists have only observed comparatively few, decisive changes: “Although there are some changes in the genome of the virus, there is as yet no evidence that certain abilities have increased or weakened, such as transferability or disease severity “writes the virologist Elisabetta Groppelli from St. George’s University of London in a statement to the British” Science Media Center “.
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The infectiologist Martin Hibberd of the London School of Hygiene and Tropical Medicine also writes: “Data from 35,000 virus genomes have not provided any evidence that the severity of the diseases has changed.” Even if that could change, it currently looks as if there must be other reasons why the cases described by Zangrillo were so different.
“One explanation could be the decreasing number of infections,” said Hibberd. While those infected without or with only mild symptoms would likely be overlooked in the event of a major outbreak, with falling numbers of cases there is now also the time to observe people with less severe problems. “And that could give the impression that the virus is changing.”
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Francois Balloux from University College London added that the role of the season also had to be discussed. Because the reasons why the outbreak in Italy as in other European countries has continued to decrease despite relaxed social distancing measures are still unclear. In particular, experts disagree about the answer to the question of the influence of temperatures.
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