Omicron Is Here. What Happens Now?

Differences between omicron and delta, and how to guard against these COVID-19 variants

Now that the omicron variant has been detected in Illinois, what can we expect in the months ahead?

We asked John Segreti, MD, an infectious disease specialist and medical director of infection control and prevention at Rush University Medical Center, to answer some common questions about omicron and what it means for the COVID-19 pandemic.

What is the correct way to pronounce omicron?

Since the variant was first detected in South Africa in late November, many have wondered how to pronounce omicron, which represents the 15th letter in the Greek alphabet.

Segreti confirmed the proper pronunciation with a colleague at Rush, who is a native Greek speaker. In Greek, it is “OH-ma-krone,” not “AH-ma-cron,” but multiple pronunciations are common.

What are the symptoms of omicron?

So far, there’s no data to suggest that the COVID-19 symptoms caused by omicron are different from those caused by delta, the dominant variant in Chicago and the rest of the United States. Symptoms of infection from either variant include cough, stuffy nose, fatigue and fever.

However, early reports from South Africa suggest that omicron may cause milder COVID-19 that is less likely to lead to hospitalization or death.

“It could be that the population affected by omicron in South Africa is younger and tends to have less severe disease,” Segreti says. “Another possibility is that for many people in South Africa, this is a reinfection and they’ve already had some partial immunity, so they are not as likely to have severe disease.” Still, it may be several weeks before scientists can say for sure if omicron causes milder COVID-19.

Early data also suggests that omicron may be more transmissible than delta. But again, data released over the next few weeks should give scientists much more information on the new variant, he says.

How can you tell if you have been infected with the omicron variant?

The only way to know is through genomic sequencing, which allows scientists to monitor how SARS-CoV-2, the virus that causes COVID-19, is changing. This is important for researchers to determine which variants are in an area and how quickly they may spread.

The first known COVID-19 case caused by the omicron variant in Illinois was identified at the Regional Innovative Public Health Laboratory at Rush using this type of analysis.

Will omicron overcome delta as the dominant variant?

It is still too soon to predict if and when omicron might surpass delta as the dominant variant. “The current surge that we’re in is being driven almost exclusively by delta,” he says. “Right now, 99.9% of cases in Illinois are still infected with delta.”

Some good news: Segreti believes the current surge in COVID-19 cases is beginning to plateau, meaning that we could start to see a decline in mid- to late December. However, social gatherings for Christmas and New Year’s Eve could drive another surge. “I wouldn’t be surprised if we saw the numbers go up a little bit in the middle of January,” he says.

And while he expects the number of omicron cases to increase in Illinois, it’s impossible to predict if there will be another surge if omicron takes over as the dominant variant.

To reduce the spread of the delta and omicron variants, some public health officials have proposed having “vaccine passports” in Chicago. Would requiring proof of vaccination to enter public places curb the spread of the virus?

The effectiveness of vaccine passports has not been studied scientifically, so it’s impossible to know if these would help put an end to the pandemic, Segreti says. However, the science overwhelmingly supports getting vaccinated.

“We know that people who are vaccinated are less likely to get infected, and if they do get infected, they’re less likely to transmit infection,” he says.

To guard against the omicron and delta variants, Segreti recommends getting vaccinated or getting a booster if you are due. According to the Centers for Disease Control and Prevention, all adults should get a Pfizer or Moderna booster if it has been at least six months since they completed their primary two-dose series with the Pfizer or Moderna vaccines. Adults who received the single-dose Johnson & Johnson shot at least two months ago should get a booster with any of the COVID-19 vaccines available.

The CDC now recommends boosters of the Pfizer-BioNTech vaccine for those ages 16 and 17 if it has been at least six months since their initial Pfizer vaccination series. Will this help us fight omicron and the pandemic?

Segreti says getting more people boosted, including adults and those ages 16 and 17, should improve immunity against omicron and reduce the spread of the virus.

“There is evidence that with omicron, the Pfizer-BioNTech booster seems to help increase the immune response,” he says.

Besides getting vaccinated and boosted, what else can people do to protect themselves against the delta and omicron variants?

It is familiar advice: Segreti recommends wearing masks and practicing social distancing in public. He also suggests staying home if you’re sick and getting tested to find out whether you have COVID-19, the flu or another virus.

“Keep doing the same things that we’ve been talking about all along,” he says.

If you have not yet received a COVID-19 vaccine or would like to get a booster, you can schedule an appointment to receive one now at our vaccine clinics.

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