Omicron may spread faster than highly transmissible delta. What you need to know about the new omicron COVID-19 variant.

Dec. 6, 2021
woman gets a COVID-19 test, which is able to check for the different variants, like omicron.
There are still more questions than answers about the newest variant of COVID-19, omicron. UCHealth experts explain what omicron is and what you can do to stay safe. Photo by Joel Blocker, for UCHealth.

Omicron, the new COVID-19 variant, is here.

So, what exactly is omicron? How concerned should you be that a new “variant of concern” is spreading around the world? Is omicron a new supervillain that will overpower delta, the current Dr. Evil of the coronavirus world? Will omicron spread even faster than delta? Will omicron make people sicker? Will vaccines be able to fight omicron? And will omicron mess up the holidays and interfere with your travel plans?

For now, there are many more questions than answers about omicron. But public health experts are advising people to immediately get vaccinated or get a booster shot if they are eligible. That’s because COVID-19 vaccines have worked very well against the original virus and all previous variants. And, a Colorado researcher who is studying exactly how coronavirus variants spread expects the vaccines to work very well against omicron.

Dr. David Beckham is a virologist and a specialist in infectious diseases. He performs research at UCHealth University of Colorado Hospital and has a laboratory on the University of Colorado Anschutz Medical Campus. He and his colleagues currently are researching the tricks that variants use to replicate and spread. Right now, Beckham is comparing how the delta and alpha variants spread. Next, he will likely compare the spread of the omicron and delta variants.

Dr. David Beckham wears protective gear as he analyzes omicron, a new variant of COVID-19.
Dr. David Beckham needs to wear full protective gear to research live viruses, including variants of the virus that causes COVID-19, in his lab on the Anschutz Medical Campus. Photo by Cyrus McCrimmon for UCHealth.

Across the world, vaccine makers and researchers are racing to test COVID-19 vaccines on omicron. Answers could come within weeks.

But Beckham is confident that vaccines will remain highly effective in protecting people from severe illness if they get COVID-19 linked to omicron.

“The vaccines that we have are really great at producing multiple different types of antibodies. If you’re vaccinated, your level of concern is a lot lower. If you’re unvaccinated, omicron provides a great reason to get vaccinated,” said Beckham, who is an associate professor at the University of Colorado School of Medicine.

“We have great data showing that the COVID-19 vaccines are very safe and they’ve been effective against all of these variants. We think they’re still going to be very effective against omicron,” Beckham said.

Dr. Michelle Barron, senior medical director of infection prevention and control for UCHealth and a professor of medicine and infectious diseases at the University of Colorado School of Medicine, is urging people to be careful, but not to panic. Stay tuned as much more information about omicron will emerge soon.

Headshot of Dr. Michelle Barron. She discusses who should get booster shots now.
Dr. Michelle Barron. Photo by Cyrus McCrimmon for UCHealth.

Early data from South Africa, where the new variant was first detected, have shown that the omicron variant may spread twice as fast as delta. (The study is preliminary and has not yet been reviewed by other scientists.) Case numbers in South Africa are increasing at an extremely fast clip and omicron appears to be very adept at reinfecting people who have already had COVID-19.

It’s unclear if the new variant will be as dangerous in areas of the world that have higher vaccination rates. In South Africa, fewer than one-third of residents have received their COVID-19 vaccines. And, until omicron cases exploded there, COVID-19 infection rates were very low. The omicron variant might have seized the opportunity to take over in a less-vaccinated population as delta cases were waning.

“Within the next couple of weeks, we’re going to know if omicron is more transmissible than the delta strain, which is causing nearly all of our infections in the U.S. now,” Barron said. “The other piece we don’t know is, ‘Does it make you sicker?’ And no one knows yet. There’s some anecdotal evidence that it doesn’t, but until you see it in a large population, it’s really hard to gauge.”

To help answer your questions about omicron, we consulted with Drs. Beckham and Barron.

So, what exactly is omicron?

Omicron is a new variant of the SARS-CoV2 virus that causes COVID-19. It’s still closely related to the original virus, but as viruses spread, they change. This new variant has adapted and changed and experts at the World Health Organization (WHO) deemed omicron to be a “variant of concern” on Nov. 26.

What are the symptoms of omicron?

It’s too early to make broad generalizations about cases of COVID-19 caused by omicron. In South Africa, and in the initial cases identified in the U.S., patients described mild symptoms including a runny nose and a sore throat; however, these individuals were fully vaccinated against COVID-19 so their symptoms may have been positively impacted by that fact.

Beckham and Barron urged people to get tested if they have any symptoms. That’s because flu cases are also beginning to hit in North America.

“Flu is here. Flu cases are rising. The flu can mimic COVID-19 or a cold. We can test for flu and COVID-19 at the same time. I encourage people to get tested. That way, you won’t inadvertently spread the illness,” Barron said.

Why is the new variant of COVID-19 called omicron?

WHO scientists use Greek letters to name variants if they’re serious enough to cause widespread infections. Delta, for example, is the dominant virus strain now causing cases of COVID-19.

“We started with alpha. We’re at No. 15 now,” said Barron. “There have been a fair number of variants, some of which no one remembers. No one remembers that beta was from South Africa.”

The most recent new variant was called “mu,” but it wasn’t able to compete against the highly transmissible delta variant, so few people know anything about mu. WHO leaders skipped over “nu” because it sounds like “new” and also skipped “xi” because it’s a common surname in Asia. Now, people around the world are learning all about omicron, a Greek letter previously known to few people outside of Greece.

How do you say omicron?

How to pronounce omicron has sparked frequent debates. Most people in the U.S. pronounce it oh-mih-cron (oh rhymes with toe). Others say aw-mih-cron. And still others say oh-me-cron. If you want to hear pronunciations, visit Merriam Webster’s dictionary.

I keep hearing about mutations. What are they and why are they important?

Dr. David Beckham conducts research on viruses. He may soon be studying omicron, a new variant of COVID-19.
Dr. David Beckham is a virologist and an expert on infectious diseases. Photo by Cyrus McCrimmon for UCHealth.

Omicron has sparked a great deal of concern because the new variant has an unusually high number of mutations — more than 50 overall and about 35 in the spike protein, which is a critical component of the virus.

“The spike protein is important both for the virus’ ability to spread and our body’s ability to fight the virus,” Beckham said.

The new mutations in omicron could supercharge the variant and make it especially good at invading cells, spreading easily and potentially making people sick.

“There’s a mutation in the spike protein that primes the virus to cause infections more easily. The delta variant has one mutation in this region and omicron has three mutations,” Beckham said.

The discovery of omicron in Botswana and South Africa in mid-November and the quick spread of omicron around the world explains why health officials are taking this new variant so seriously.

Are the variants that cause COVID-19 changing more rapidly than typical variants?

No. It’s normal for viruses to adapt and change, Beckham said.

What’s different now is that scientific advances allow researchers to closely monitor variants and immediately share news about them.

“This is the first time in human history that we’ve had a pandemic and have had the ability to rapidly sequence the virus in real time,” Beckham said.

“What people are seeing is the evolution of a new virus that just jumped into humans. It’s adapting to us and to our respiratory systems. We’re just watching these mutations develop in real time,” Beckham said.

Why did experts at the World Health Organization act so quickly to declare omicron a variant of concern?

“Omicron has many mutations that could allow it to spread better and be better at binding to and getting into our cells,” Beckham said.

So, concern and quick action by global health leaders is warranted, both Barron and Beckham said.

Will the current COVID-19 vaccines work to protect us against the omicron variant?

The vaccines have worked well against previous variants. Researchers and vaccine makers are testing the vaccines against omicron now. More news should come soon about how effective the current vaccines are in fighting omicron.

Why should unvaccinated people immediately get vaccinated?

People who are not vaccinated have no protection against the variants. Early reports from South Africa found that many people who previously had gotten COVID-19 became infected with omicron. So, it’s clear that antibodies to a previous natural infection do not prevent re-infection with the omicron variant, Beckham said.

How do COVID-19 vaccines help protect people from omicron?

“The vaccines are preventing the coronavirus (whether from delta or omicron) from getting into the lungs and making you really sick. That’s the benefit of the vaccine,” Beckham said.

“We’ll definitely see breakthrough cases. The viruses are really good at replicating in the upper airways, but most vaccinated people will have milder symptoms if they get sick,” Beckham said.

The delta variant is highly transmissible and adept at spreading and infecting new targets, Beckham said. But for those who are vaccinated, the infection tends to be milder and to stay in people’s upper airways rather than becoming much more severe and moving into the lungs.

If I’m vaccinated and I get COVID-19 from the omicron variant, how sick will I be?

It’s too soon to know for sure. But, early information from South Africa and the first confirmed cases of omicron in the U.S. have found that vaccinated people who contracted the omicron variant have had relatively mild cases. This means that they can still feel sick, but health authorities have said many haven’t needed to be hospitalized.

That’s been true for breakthrough cases of COVID-19 tied to the delta variant too.

“The vast majority of people who get breakthrough delta cases tend to get the sniffles and stay home. Most of these folks are not ending up in the hospital or in the ICU,” said Beckham.

Dr. David Beckham,, center, in the lab where he conducts research on viruses. With him are Camille Merrick, left, a lab technician and research assistant, and Brendan Monogue, a PhD student in microbiology. In the background is Dr. Kelsey Lesterberg, a research instructor in Beckham's lab. Photo by Cyrus McCrimmon for UCHealth.
Dr. David Beckham, center, in the lab where he and his colleagues conduct research on viruses, including variants of the virus that casues COVID-19. With Beckham are Camille Merrick, left, a lab technician and research assistant, and Brendan Monogue, right, a PhD student in microbiology. In the background is Dr. Kelsey Lesterberg, a research instructor. Photo by Cyrus McCrimmon for UCHealth.

Why did the discovery of omicron spur such quick action from world leaders and public health experts?

“In South Africa (where omicron was first detected) omicron has overtaken delta as the primary subtype that’s being seen,” Barron said. “That suggests that it may have the same potential to spread really quickly.”

Where did omicron originate?

New variants develop in unvaccinated people all over the world where the virus is spread. Scientists in South Africa first sequenced omicron, but the variant may have originated elsewhere. Due to the history of AIDS in Africa, South Africa is home to many experts on viruses. These researchers have pivoted during the pandemic to study COVID-19. They have been routinely studying and sequencing variants of the SARS-CoV2 virus. While Africans have been stigmatized over omicron, world health leaders have praised researchers there for closely monitoring the virus and immediately sounding the alarm when they discovered omicron.

Can vaccine makers create new COVID-19 vaccines to directly target the omicron variant?

Yes, Barron said.

“That’s the beauty of this technology. The vaccine makers are really nimble. If they had to make vaccines, they could do it pretty quickly,” Barron said.

If people need to get new COVID-19 vaccines, Barron predicts that manufacturers would have them produced and delivered within a couple of months.

“But I don’t know that we’ll need them,” Barron said. “It’s premature.”

Should I wait to get a booster until there’s a new vaccine?

No. Don’t wait for additional information about omicron. Anyone age 18 and over who is eligible to get a booster shot should do so right away, said Dr. Anthony Fauci, chief medical advisor to President Joe Biden.

Can current COVID-19 tests detect the omicron variant?

Yes, said Barron.

“The good news is that the standard testing we’ve been using is working. Omicron is similar enough to other variants that the PCR tests and the antigen tests that we’ve been using all along are still available and work just fine.”

How will I know if I have omicron?

You probably won’t. If you are sick or have any symptoms of a cold or COVID-19 (even mild symptoms) get tested. A percentage of people who test positive for COVID-19 in each state will have their test samples “sequenced.” State health officials and experts at the Centers for Disease Control and Prevention (CDC) can sequence the samples and determine which variant is causing the illnesses.

Because omicron is still new, the few people in the U.S. who have tested positive thus far have learned that they have the omicron variant and they are isolating themselves.

If omicron overpowers delta, many people who get COVID-19 may have the omicron variant, but won’t know exactly which variant made them sick.

How can people protect themselves against the omicron variant of COVID-19?

“COVID-19 is here. It hasn’t gone away,” Barron said. “All of the things that we’ve been talking about for two years are still highly effective ways to prevent the transmission and spread of COVID-19: vaccination, masking, washing hands, and practicing social distancing.

“I know everybody is probably saying, ‘Can’t I take a pill and be done with it?’ And the answer is no. This is still the way it works.”

woman gets a booster shot to protect herself against the new covid variant, omicron, as well as all the other variants.
Getting a COVID-19 vaccine is still the best way to protect yourself against COVID-19, whether delta keeps spreading or the new omicron variant takes over soon. Photo by Cyrus McCrimmon, for UCHealth.

How concerned should people be about omicron?

The virus that causes COVID-19 is spreading widely. So, people should be cautious no matter what.

“Omicron is just a reminder. I don’t think people need to panic, but I also think they need to recognize how bad things still are,” Barron said. “I understand we’re tired and over it, but the virus doesn’t care. It has no consideration for our feelings. It wants to survive. How does it survive? It changes and finds new hosts. It’s just the challenging reality we live in.”

Does it make any sense to allow omicron to spread widely so more people will develop immunities to the new variants?

No. Fauci and other health experts say it’s dangerous to try to boost immunities by allowing a variant like omicron to freely spread.

Barron and Beckham also advised people to get vaccines because they offer greater protection than natural immunity. If omicron proves to be highly contagious, it could also cause severe illness in unvaccinated people and become quite dangerous.

“If you take the approach of letting omicron spread, you’re going to have a significant number of people dying,” Beckham said. “It’s not true that people can develop a natural immune response and will be fine.”

Why are vaccines more effective in helping people fight COVID-19 infections than antibodies from natural infections?

The newest data from South Africa show that the omicron variant may be three times more likely than the delta variant to reinfect people who have already recovered from COVID-19.

“Reinfection in unvaccinated people is a real concern,” Beckham said. “These viruses are getting better and better at triggering these infections.”

Beckham said vaccines give much better immunities because they prompt our bodies to recognize and react to multiple regions of the spike protein.

“Your body sees the spike protein as a foreign object and triggers an immune response with both T cells and B cells. Up and down this entire spike protein, your body creates responses. That’s why it’s really hard for viruses (and variants) to escape these vaccines,” Beckham said.

When a person gets a natural infection, the body makes some antibodies, but the response is not as broad and the immune response may not last as long as the vaccine-generated response.

“In order for the virus to escape vaccines, it would have to develop an entirely new spike protein. That’s why vaccines are so good. They stimulate this robust, broad response,” Beckham said.

While omicron has more than 50 mutations, that’s still a small percentage of the total number.

“There are about 35 amino acid mutations and the spike protein has over 1,200 amino acids or building blocks for the protein. It would be very difficult for the virus and the new omicron variant to escape the whole immune system.”

Are you worried about increases in cases of COVID-19 over the holidays, whether they are linked to delta or omicron?

Yes, said Barron. “That’s a big concern. After every major holiday, we see a spike. We’re just hoping that people have gotten their vaccines and are being smart about testing so they don’t spread it. The other piece of the equation is that flu cases are definitely becoming more widespread, and we don’t want people to forget the flu is out there. We are concerned about people requiring hospitalization for the flu, so when you’re thinking about the COVID-19 vaccine, also think about getting your flu shot if you haven’t already.”

ICU nurse at UCHealth gets ready to go into a COVID-19-positive patient room. A spike in COVID-19 cases due to the new omicron variant could cause issues for already full hospitals.
An ICU nurse at UCHealth gets ready to go into the room of a patient who has COVID-19. A spike in COVID-19 cases due to the new omicron variant could cause increased crowding at hospitals that are already full. Photo by Joel Blocker, for UCHealth.

Is it OK to gather with friends and family over the holidays?

“If you aren’t vaccinated, get vaccinated. If you aren’t boosted, get your booster,” Barron said.

“It’s premature to know how to approach the holidays,” Barron said.

Dr. Fauci recently said that fully vaccinated people should feel safe gathering indoors without masks. But, if you are anywhere in a crowded setting indoors and you do not know the vaccination status of everyone around you, Fauci encouraged people to wear masks and be careful.

Is it OK to travel internationally now?

Barron advises caution. It’s also wise to review the CDC’s travel advisories and new requirements for Americans returning to the U.S. and international travelers who are arriving. Everyone who comes to the U.S. on an international flight now needs to have a negative COVID-19 test less than 24 hours before returning. The logistics of getting those tests can be challenging.

“If you have plans to travel internationally now, be very aware of the testing and vaccine requirements,” Barron said. “And, if the borders close, what is your plan? We went through this in 2020. If you are making plans, be sure to have a ‘Plan B’ in place.”

Why are some variants more successful than others?

“Variants of viruses are constantly developing, and most are not successful. Often, they’re not transmissible enough, or they’re beaten out by a stronger variant.  It’s kind of like survival of the fittest, on a microscopic yet world-wide scale,” Barron said.

If omicron is more transmissible than delta, would delta go away? 

“Yes. If Omicron proves to be more transmissible than delta, it’s possible that it would replace delta and become the dominant strain of COVID-19,” Barron said. “This is what happened in spring of 2021 when alpha replaced the original COVID-19 strain, and again this fall as the delta variant replaced the alpha variant. Right now, in Colorado, nearly 100% of the cases we are seeing are from the delta variant.’’

It’s also possible that omicron won’t take over.

“Beta, epsilon and other variants have popped up, then disappeared as stronger strains of the virus have taken over,” Barron said.

Are there seasonal patterns to COVID-19 infections and the emergence of new variants?

Infectious disease experts have not yet identified seasonal patterns related to COVID-19.

It’s common for other viruses to surge and decline seasonally. Flu cases, for instance, increase in the winter. In South Africa, summer is on the horizon; yet omicron cases are rising dramatically. In the U.S., delta cases have been very high since late summer and are expected to continue surging this winter. Holiday gatherings may be more to blame than seasonal variations, Barron said.

Someday, it’s likely that COVID-19 infections will wax and wane seasonally, but that’s not the case yet, Barron said.

How do mutations develop? I hear they are ‘mistakes.’ Is that correct?

Yes, as viruses spread and copy themselves, they make some mistakes (which produce mutations and variants), Beckham said.

“Some mistakes will be bad and the virus will die out. Some mistakes will help the virus spread more easily,” Beckham said. “Viruses intentionally optimize their ability to spread.”

About the author

Katie Kerwin McCrimmon is a proud Coloradan. She attended Colorado College thanks to a merit scholarship from the Boettcher Foundation and worked as a park ranger in Rocky Mountain National Park during summers in college.

Katie is a dedicated storyteller who loves getting to know UCHealth patients and providers and sharing their inspiring stories.

Katie spent years working as an award-winning journalist at the Rocky Mountain News and at an online health policy news site before joining UCHealth in 2017.

Katie and her husband, Cyrus — a Pulitzer Prize-winning photographer — have three adult children and love spending time in the Colorado mountains and traveling around the world.