Claims of a Weaker COVID-19 Virus Disputed

Sonya Collins

June 03, 2020

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After Italy saw its first case of COVID-19 in late February 2020, the country quickly became a global hub for the virus. With over 233,000 cases and more than 33,000 deaths to date, the virus was more fatal in Italy than in China. To slow the spread, the government ordered everyone to stay home. Now, infection rates are finally falling.

And as the country begins to reopen, a handful of Italian doctors say the deadly virus is losing steam.

"In March and April, patients reached the emergency room very sick. They had acute respiratory distress syndrome, multi-organ failure. They needed immediate oxygen, ventilation, and in two to three days, we had patients that died," says Matteo Bassetti, MD, director of the Infectious Diseases Clinic at the San Martino Hospital in Genoa. "But now, in the past four to five weeks, it's been totally different. Patients of a similar age as the ones before, even very elderly patients, are not as sick as patients were just four to six weeks before."

In stark opposition to Bassetti's and other doctors' statements, Italian public health officials and the World Health Organization (WHO) warn there's no evidence to support these claims. They urge health care providers and the public to continue to take the virus extremely seriously. Meanwhile, Bassetti says proof is on the way.

Can a Virus Weaken?

"One of the golden rules of virology," says Mark Cameron, PhD, an associate professor of population and quantitative health sciences at Case Western Reserve University School of Medicine, "is that viruses that circulate in the community do change and mutate."

They do this, he says, to survive. A virus that's deadly enough to kill all of its hosts will die out as soon as the last infected person dies. A weaker form of the virus -- one that doesn't make people quite as sick -- can continue to travel from person to person.

"A virus is interested in its own survival," says Cameron. "It needs to maintain high viral fitness and not kill its host -- us. COVID-19 has already struck that perfect balance."

It could take generations for enough genetic change to take place to substantially weaken a coronavirus -- both the one that causes COVID-19 and other forms that were around before it. Human coronaviruses are known to be extremely stable in their genetic makeup. They change very little over time. Early tracking of SARS-CoV-2, the coronavirus that causes COVID-19, suggests that it is behaving like its relatives, changing slowly and subtly over time.

That's not to say that the virus isn't changing at all. When researchers at Arizona State University analyzed coronavirus samples collected from nasal swabs, they found one individual sample that had a major genetic difference from other samples.

But it's unknown whether this particular variation of the virus results in more or less severe illness or any difference in symptoms at all. To confirm a theory like that will require much more research. Scientists will need to align the various genetic sequences of numerous nasal swabs with patient symptoms.

Still, Cameron says, this single mutated sample won't prevent other strains from continuing to spread and cause illness. Viral strains survive independently of each other. That's why, for example, several flu strains circulate every season.

With so many people infected with SARS-CoV-2, a mutation in a single sample is unlikely to change the course of the outbreak, Cameron says.

Though researchers say it's unlikely that the virus has mutated enough to make major differences in how severe an illness will be, that's not all bad news. That makes the virus a stable target for researchers working on a vaccine. The flu, for example, changes so quickly that vaccine developers have to come up with a new shot every year.

Proof Is on the Way?

Public health officials stress there's no scientific proof that the virus is now weaker. Until that proof is found, health authorities warn that the public cannot lower its defenses against the spread of the virus. But Bassetti promises the evidence is coming. He cites studies in progress in the northern Italian cities of Milan and Brescia that will show that people are carrying lower viral loads than before -- a sign of less severe disease -- and that genetic mutations in the virus have made it less deadly.

One of the golden rules of virology is that viruses that circulate in the community do change and mutate. Dr Mark Cameron

"We are not here to say that the virus is gone," Bassetti says. "We are here to say that it is different." He attributes these differences to a potential combination of things, including biological changes in the virus, and the success of the lockdown, social distancing, mask use, and hand-washing. Flattening the curve, Cameron adds, allows testing to catch up and makes medical care available to those who need it without delay.

In response to the WHO's rebuttal of his claims, Bassetti says, "The WHO does not take care of patients. They are seated at a table in Geneva. These are the impressions of the majority of doctors on the ground. We have admitted more than 500 [COVID-19] patients at San Martino hospital since the beginning of the epidemic, and I have seen a dramatic reduction in the severity of the disease."

It could be that the work of on-the-ground health care providers is responsible for this dramatic change, Cameron says.

"I would lay the credit for the consistently improving patient outcomes in Italy right at the doctors' and health care workers' feet," he says. "It's a testament to their heroics that they've broken this virus's back without much, if any, help from the virus itself. We will have to wait for virus sequencing studies and clinical studies to resolve the issue."


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