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The Coronavirus is Not Less Potent, Despite a Claim

A report out of Italy prompts swift rebuttals from multiple experts

Robert Roy Britt
3 min readJun 2, 2020


The claim by an Italian doctor on Sunday that the coronavirus that causes Covid-19 no longer exists there led to an article suggesting the virus was losing potency. Experts swiftly dismissed the suggestion.

“In reality, the virus clinically no longer exists in Italy,” Alberto Zangrillo, head of the San Raffaele Hospital in Milan, said. “The swabs performed over the past 10 days have showed a viral load that is absolutely infinitesimal in quantitative terms compared to those carried out a month or two months ago.” He added: “Someone has to take responsibility for terrorizing the country.”

(“Viral load” is the amount of virus found in a test sample from a person, reflecting how well a virus is replicating in that person.)

The story was picked up by Reuters, with the headline “New coronavirus losing potency,” getting widespread attention.

“He is wrong,” tweeted Angela Rasmussen, a virologist and research scientist at the Center of Infection and Immunity at the Columbia University School of Public Health. “There is no evidence that the virus is losing potency anywhere. There is less transmission, which means fewer hospitalized patients and fewer deaths. That doesn’t mean less virulence.”

Rasmussen and other scientists and journalists also called on Reuters to take the story down or correct it.

Viruses can mutate, evolving to become more or less effective at causing infections or generating symptoms. But there’s no evidence that the SARS-CoV-2, which causes Covid-19, has mutated in any way that changes its spreadability or its deadliness.

“The virus hasn’t lost function on the time scale of two months,” said Andrew Noymer, an epidemiologist at the University of California at Irvine. “Loss of function is something I expect over a time scale of years.”

The Reuters story seems to be a misinterpretation of the original claim, at best.

The inherent ability of SARS-CoV-2 to spread and cause a variety of symptoms, from mild to severe, has not changed, says Maria Van Kerkhove, an epidemiologist with the Health…



Robert Roy Britt

Founder/editor of Wise & Well on Medium & the Writer's Guide at & author of Make Sleep Your Superpower