Fact check: The theory that SARS-CoV-2 is becoming milder

The disease COVID-19 is caused by the virus that is shown in the transmission electron micrograph image. The specimen was isolated from a US patient. The cells in the lab have yellow particles emerging from them.

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There's a growing narrative in the mainstream media and on social media. The coronaviruses is evolving into a less deadly virus. Each new variant will cause milder illness than the previous variant in the future.

"There's a story that we're going to have variant that are less severe," says Dr. Roby Bhattacharyya, who is an infectious disease specialist at Massachusetts General Hospital and Harvard Medical School.

That's not true, says Bhattacharyya. It's comforting to think that there might be a tendency for the disease to evolve into a milder form. That's not what we're seeing.

The mild theory's beginnings.

Over the past month, scientists and doctors have found evidence that the omicron variant of the coronaviruses is less likely to cause severe disease than previous versions.

Data from hospitals in South Africa, the U.K., and the U.S. show that the risk of a patient with omicron being admitted to a hospital is less than with the delta variant. If you are admitted to the hospital, the risk of being put on a ventilator has gone down.

Experiments and animal studies show that omicron acts differently in the lungs than previous versions. The University of Cambridge found that omicron doesn't cause as much damage to lung cells as delta does.

The team looked to see how well omicron and delta could cause lung and respiratory organoids, which are small clusters of cells that resemble specific types of tissues in the lungs and respiratory tract. Omicron grew more slowly than delta inside the lung cells. The team did not see a difference in upper respiratory cell replication.

"Omicron's growth was disabled in cells that were very aggressive," Gupta says. "That was a real shock, because we were seeing omicron spreading very, very rapidly globally and yet omicron's ability to grow in certain cell types was really diminished."

The team found that omicron uses a different path to enter cells. The alternative entryway is likely to cause less damage to the lungs. Patients with less inflammation in the lungs and a reduced requirement for supplemental oxygen are being affected by the differences.

The findings were published online by Gupta and his team. The media "seized upon them as a sign of the end of COVID," Gupta says. I was worried about the narrative because omicron is still a very dangerous infection.

The emergence of a less severe variant like omicron is not a sign that the virus is less able to cause lung problems.

Gupta says that the next variant may not evolve from omicron and may not have the same characteristics.

An evolutionary history of the disease.

According to Bhattacharyya, before omicron came along, the disease was getting more severe. He says that they are looking at a virus that has gotten more severe over time.

Alpha was found to be 40% more likely to kill a person than the original virus. Delta was more likely to put you in the hospital than the alpha variant.

Omicron may be a small step back in severity. It's probably more severe on its own than the original version. He says that becoming "more mild" hasn't been a trend.

omicron didn't evolve from delta. The earlier version of the virus was circulating in 2020. Omicron could be more severe than its ancestors, and it could be progressing toward higher severity.

There is no guarantee that the next variant will be milder. It could be the most severe yet.

Evolutionary Biologist Stephen Goldstein at the University of Utah says that they don't know what direction the virus is taking. Trying to predict the evolutionary trajectory of the virus is very difficult. If not impossible.

What will the future COVID-19 surge look like?

The spread of the disease from one person to another occurs at the beginning of the disease. The person's upper respiratory tract is the most affected by the virus. It hasn't reached the deepest part of their lungs, where severe disease occurs.

Mild or moderate illness in the upper respiratory tract is the primary way that SARS-CoV-2 survives. Gupta says that using severe illness is not one of the survival strategies of the disease.

A new variant needs to become good at infecting a person's nose and airway if it is to spread and out compete previous versions. It doesn't matter how well the new variant works. A new variant of the disease needs to be good at evading immune responses as more people become immune.

Future versions will likely improve their ability to grow in the upper respiratory tract and be more immune evasive.

"If those changes also make the new variant more severe or less severe, that's kind of luck of the draw", says Bhattacharyya.

There are other scenarios besides doom and gloom.

On the surface, this sounds terrible. It suggests that the next surge could be worse than the delta surge.

That's probably not possible, says the man. People's immunity is one more factor to take into account.

Your immune system is just like the virus. More than half of the U.S. population is likely to have been exposed to the disease. The percentage could go above 80% or 90% after the omicron surge. More than half of the people are protected from diseases.

A person's risk of severe disease in the future will be reduced by two types of exposure to the disease. "If you've been exposed to a disease, you're more likely to have a milder course than someone who's not," he says.

Future versions of the virus will likely look less severe than earlier versions. If the population has a high level of immunity, the variant will be less virulent because the average severity of infections will go down over time.

The hope among scientists is that future waves of COVID will be less deadly and less disruptive because our bodies will be better able to handle the virus.