We all want the Omicron variant to be milder. Here’s why it’s too soon to know

Early reports on the quick spread of the Omicron variant in South Africa were at first frightening, but then began to offer some hope. The new variant may have quickly overtaken other strains of the virus in South Africa as it enters the summer, but cases so farappear to have been overwhelmingly mild.

Then came a report showing the variant carries a portion of genetic material that’s very similar to segments seen in one of the types of coronaviruses that causes the common colds – one called HCoV-229E. A few researchers said it just might indicate the variant is starting to look more like a nuisance virus than a big killer.

It’s a tantalizing idea. Many infectious disease experts have been predicting that the novel coronavirus, named SARS-CoV-2, would go in this direction, evolving into a milder form that joins the annual mix of seasonal respiratory viruses.

Could this be the variant that at least starts it down that path?

It is way too soon to start thinking that, several experts told CNN. For one thing, that segment of genetic material may resemble a piece of the common cold virus, but it’s a very big stretch from there to say that means SARS-CoV-2 has started to evolve into something milder.

“Even assuming the insert came from a common cold virus – that’s very dicey – it probably would not make it more like the common cold virus,” virologist Robert Garry of the Tulane University School of Medicine told CNN.

It’s a small piece of genetic material and not one that’s necessarily on a part of the virus that would affect its virulence, Garry said.

“The idea that this variant is milder is just pure speculation. There is no reason to think it is,” said Michael Worobey, who heads the department of evolutionary biology at the University of Arizona.

It takes time to develop severe illness

Plus, there hasn’t been quite enough time to assert that real-life experience with Omicron shows it causes mostly mild disease.

An illustration picture taken in London on December 2, 2021 shows a vial with Covid-19 vaccine sticker attached, beside syringes and a screen displaying the word 'Omicron', the name of the new covid 19 variant. (Photo by Justin TALLIS / AFP) (Photo by JUSTIN TALLIS/AFP via Getty Images)

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It takes anywhere from two days to two weeks to develop symptoms after exposure to coronavirus, according to the US Centers for Disease Control and Prevention.

There hasn’t been quite enough time to know how likely Omicron is to cause severe disease, said Dr. William Schaffner, medical director at the National Foundation for Infectious Diseases and an infectious diseases expert at Vanderbilt University.

“There’s a distinction between hopeful and reality. It’s good to hope but it is much too early to conclude that Omicron only produces mild infections. We don’t have those data,” Schaffner told CNN.

“Covid has thrown us several curveballs.”

The data from South Africa, the first country to spot the Omicron variant, does look hopeful.

People queue for a PCR Covid-19 test at the Lancet laboratory in Johannesburg on November 30, 2021. - A new, heavily mutated Covid-19 variant, dubbed omicron, spread across the globe on Sunday, shutting borders and renewing curbs as the EU chief said governments faced a "race against time" to understand the strain. (Photo by EMMANUEL CROSET / AFP) (Photo by EMMANUEL CROSET/AFP via Getty Images)

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“We are not seeing many severe cases. I want to caution we’ve only known about this for a week so it’s early days,” Dr. Salim Abdool Karim, an infectious diseases epidemiologist who is helping coordinate South Africa’s response to Covid-19, told CNN.

“I’ve been speaking to the chair of our medical association. She collects this data from all the doctors, and essentially what they are saying to us at this stage is that the cases are generally mild,” he added. “Now, one has to be very careful in overinterpreting that, because it’s still very early days, in that severe cases usually take longer. They occur in weeks two, three and four. So it may be that severe cases will follow later.”

Schaffner puts it a little more bluntly. “Death is a lagging indicator,” he said. “It takes time to progress to serious infection. It takes time for more serious infections to follow,” he said.

Different populations in different countries

Dr. Amesh Adalja, senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health, said he hopes early reports do indicate Omicron might cause milder disease.

“It raises the possibility that maybe this is not going to be as bad as some people were fearing,” Adalja told CNN.

“That doesn’t mean it’s not bad at all,” he added. “The caveat is that South Africa has a younger population.”

Younger people have been less likely to develop severe disease from Covid-19, which has killed 5.2 million people globally and 789,000 in the United States alone, according to Johns Hopkins University.

COVID-19 sample viles are shown during preparation for isolation and extraction at the Genview Diagnosis lab on August 13, 2021 in Houston, Texas.

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But more people are vaccinated in the US than are in South Africa. Studies of vaccines against Omicron are underway.

“I think it ispretty easy to say if you are fully vaccinated, the breakthrough you get with Omicron is going to be milder,” Adalja said. “Even if this gets around some of our vaccine-induced protection, it is not an all-or-done effect.”

And it’s becoming evident that Omicron is highly transmissible. “Over the last week, the number of daily infections has increased five-fold,” South African President Cyril Ramaphosa said in a weekly newsletter Monday.

The rate of positive Covid-19 tests in South Africa has jumped by 24% since the Omicron variant was detected two weeks ago, according to the latest data from the South African National Institute for Communicable Diseases.

A virus that is more transmissible while causing milder disease is just what scientists would expect to see in something that was evolving to become more like other common cold viruses.

“Those of us who know that this is going to be an endemic respiratory virus have been waiting to understand what the virus does in order to become more like its other family members that cause about 25% of our common colds. So people are on the lookout for those changes. And maybe this is that – maybe it’s not,” Adalja said.

‘The old enemy’ Delta remains dominant

Plus it’s not clear Omicron can out-compete Delta in countries like the United States, said Johns Hopkins’ Dr. Crystal Watson.

Scientists work on the COVID-19 at the Centre for Epidemic Response and Innovation in KwaZulu-Natal, South Africa. Prof Tulio de Oliveira, the director of the Centre for Epidemic Response and Innovation in South Africa, said there was an unusual constellation of mutations and that it was very different to other variants that have circulated. In a media briefing Prof de Oliveira said there were 50 mutations overall and more than 30 on the spike protein, which is the target of most vaccines and the key the virus uses to unlock the doorway into our body\'s cells.

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“Even if we do have good protection against severe illness and death from vaccines, a big surge in Omicron could still be dangerous if it is highly transmissible,” said Watson, a senior associate at the Johns Hopkins Center for Health Security.

“High numbers can still mean many people in the hospital,” she said. “There will be some people, a large enough population to create stress on the healthcare system, who will not be as protected by vaccination or from prior infection.” That could lead to more pressure on already stressed hospitals.

“Our health care system is just so fragile right now,” Watson said. “We have lost a lot of staff, and people are really exhausted. The system itself is depleted.”

That’s the same around the world, noted Francois Balloux, director of the University College London Genetics Institute.

“Early, largely anecdotal evidence suggests Omicron may be less virulent than Delta. This would be good news if confirmed, in principle,” Balloux said in a statement.

“It remains that even if Omicron infections were associated to fewer hospitalizations and deaths, a small fraction of severe outcomes out of a very large number of infections could still cause intense pressure on health care systems.”

And Schaffner is worried that unvaccinated people may take reports of a milder variant as a reason to continue to put off vaccination.

“While we are preoccupied and fascinated by Omicron, Delta, the old enemy of the summer is still here causing damage,” he said. “We have all got to be vaccinated. All this enchantment with Omicron is not an excuse to not get vaccinated.”

CNN’s Niamh Kennedy, Larry Madowo, Wayne Chang and Naomi Thomas contributed to this report.