What We Know -- and Don't Know -- About the Omicron COVID Variant

Kelly Wairimu Davis, MS, and Damian McNamara, MA

November 29, 2021

Health experts across the globe are raising concerns about the newly discovered COVID-19 variant, Omicron, which was first identified in South Africa. The country's minister of health announced last week that the variant had already spread in different areas of the country. 

The next day, the World Health Organization designated Omicron a "variant of concern." 

President Joe Biden echoed this statement at a news briefing today, but he stressed that the new variant is a "cause for concern, not a cause for panic."

COVID-19 vaccine makers are looking into the vaccine's protection against the new variant.

"The mutations in the Omicron variant are concerning, and for several days, we have been moving as fast as possible to execute our strategy to address this variant," Stéphane Bancel, CEO of Moderna, said in a statement

Pfizer says that data about its vaccine's protection against Omicron should be released in the coming weeks. 

A number of countries are making efforts to prevent the global spread of Omicron. The US is just one of a number of countries that have placed new travel restrictions on South Africa and its neighboring countries. 

So what makes Omicron different from other COVID-19 variants? And how concerned should we be? Health experts help us break it down. 

What Do We Know So Far? 

There is a lot that we don't know about Omicron, including whether it causes more severe illness than other variants, says Leana Wen, MD, MSc, an emergency doctor and public health professor at George Washington University in Washington, DC.

But we do know that it's a variant with an unusually high number of mutations, or changes in the virus' genetic material. 

Early evidence also shows that the Omicron variant may spread easier than other COVID-19 variants, she says. 

"That's very concerning because Delta, which is the dominant variant here in the US and around the world, is already extremely contagious. So, if this is even more contagious, it could displace the Delta variant," says Wen.

Is the Omicron Variant in the US?

As of right now, no cases of the Omicron variant have been reported in the US. 

Either way, you should stay calm, says William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University Medical Center in Nashville, Tennessee.

"Even if it were to be here in the United States, the dominant — the 99% that is causing disease in your community today — that strain is Delta," he says. "And we know the vaccines work against Delta."

Will COVID-19 Vaccines Work Against Omicron?

"We don't know whether the large number of mutations renders the vaccines less effective against this variant," says Wen. "Although many scientists believe — especially with a booster shot — that it's not going to render the vaccines ineffective."

What Are Common Symptoms?

We don't have that information yet, says Wen.

What Can I Do Right Now to Protect Myself and My Loved Ones?

If you are still weighing whether you should get a COVID-19 shot, the Omicron variant is one major reason to get vaccinated as soon as possible, Wen says. "That includes adolescents and children 5 to 11."

This is also a great time to get your COVID-19 booster, according to Schaffner. 

Booster shots raise your antibody levels, which offers you both longer protection and stronger immune response against COVID-19 variants, he says. 

"I can't tell you exactly what it [a booster shot] will do against Omicron, but there is likely to be, at the very least, partial protection," Schaffner says.

"And partial protection is always better than no protection."

What Should I Be Most Concerned About?

Virus spread, serious illness, and vaccine effectiveness work hand in hand. Therefore, all three are concerning, Wen says.

"Let's say that something is more transmissible, but it doesn't cause more severe disease and the vaccines work very well against it. That's not particularly concerning," says Wen. "Or, if something is not very contagious but it's still more severe, it's also not as concerning because it's not going to displace Delta."

"So, it really is a combination of these factors that could make this variant very worrisome," she says. 


Leana Wen, MD, emergency doctor and public health professor, George Washington University.

William Schaffner, MD, professor of preventive medicine and infectious diseases, Vanderbilt University Medical Center, Nashville.

Moderna: "Moderna Announces Strategy to Address Omicron (B.1.1.529) SARS-CoV-2 Variant."

News briefing, President Joe Biden, Nov. 29, 2021.


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