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What Are the Symptoms of Omicron?

Signs of a COVID infection caused by the variant can come on fast and mimic a cold for some

man sneezing into a tissue

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Health experts are quickly learning about the characteristics of the new omicron variant that is driving a record-breaking spike in COVID-19 cases, including some of the symptoms it causes.

It isn’t always the case that a new version of the virus brings about a new batch of symptoms. “The symptom differences between people infected with one variant or another are usually much more similar than they are different,” says Scott Roberts, M.D., assistant professor and associate medical director of infection prevention at Yale School of Medicine. And for the most part, that seems to hold true with omicron. But researchers and medical professionals have noted a few small differences between omicron and its predecessors.

For instance, loss of taste and smell appears to occur less often in omicron infections. It’s something health experts are hearing anecdotally; there are also early studies that support these observations, though University of Michigan infectious disease physician Laraine Washer, M.D., says there’s not enough population-level data yet to know for sure. Backaches and night sweats have also been associated with omicron. “But ultimately, we haven't detected any clear difference between omicron versus delta,” Roberts says. “We've been advising people just to wait until the data comes out.”

The one big difference that we're anecdotally hearing [is] there's much less loss of taste and smell with the omicron variant compared to delta.

— Scott Roberts, M.D., assistant professor and associate medical director of infection prevention at Yale School of Medicine

Milder symptoms but more contagious

What’s becoming clearer, however, is that omicron, while highly contagious, appears to cause more mild, coldlike symptoms. “Many people are presenting with sore throat, nasal congestion, headache, muscle aches,” Roberts says.

Data collected so far show that individuals infected with omicron are significantly less likely to be hospitalized than those infected with delta, even though hospitalization rates are at an all-time high due to skyrocketing case counts. They’re also less likely to require intensive care. This is not the case for everybody, experts caution. Some patients experience serious symptoms with omicron, like trouble breathing, Washer notes. “We are still seeing people end up on ventilators and having severe disease,” Roberts adds.

Health experts are trying to determine whether omicron’s less severe symptoms are a product of the variant itself or a reflection of a majority-vaccinated population that is better able to blunt some of its worst effects. The vaccine-plus-booster regimen is about 75 percent effective against symptomatic disease, and protection against severe disease is likely higher, researchers report. Both Roberts and Washer say the majority of people who are hospitalized with COVID-19 are unvaccinated.


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Another explanation: Lab studies suggest that the omicron variant does not replicate as well in the deep lung tissue — an area notoriously damaged by delta and other variants — rather, it thrives in the upper airway. “Perhaps that is why we're not seeing as severe disease,” Roberts says.

Signs of omicron infection can come on quickly

Another noticeable difference between omicron and other coronavirus variants is how quickly the symptoms hit. Fever, sore throat and fatigue caused by omicron are more likely to show up about three days after a person is infected, whereas symptoms caused by delta, alpha and others typically emerge about five or six days after infection, Washer says.

Getting sick soon after exposure can help people better pinpoint when and where they became infected. “But it also means that the increase in viral load that's causing symptoms comes on pretty fast,” Washer says. “And you may actually be infectious to others even before those symptoms develop.”  

Omicron’s shorter incubation period, as it’s called, could lead to new testing guidelines, Roberts points out. Current recommendations advise individuals to wait at least five days after having contact with a COVID-positive individual before taking a test. “They may shorten that to as little as three days after getting exposed just to be sure,” he says.

Cold and flu season adds to confusion

While milder symptoms are better in many respects, omicron will make it more difficult for people to tell what’s COVID-19 and what’s just a cold — or the flu or a whole host of other respiratory illnesses that circulate this time of year.

Most Common Symptoms of COVID-19

People with COVID-19 report a wide range of symptoms. The most prevalent are:

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Source: Centers for Disease Control and Prevention

Roberts says the solution is to “take any symptom seriously, even a mild symptom.” And if there’s a change in how you’re feeling, take an at-home test — if you can find one. Rapid antigen tests can tell you whether you have a COVID-19 infection in about 15 minutes with a swab of the nose or throat. Home tests are in short supply because of high demand, though the federal government has pledged to make them more accessible in the coming months.

If your test comes back positive, health officials recommend a minimum five-day isolation period. After five days you can be around others again while wearing a mask, as long as you are fever-free and feeling better. And don’t forget to tell your health care provider that you have COVID-19. Depending on your medical condition and drug availability, you may qualify for treatment to make sure the disease does not progress to a more dangerous state. Also, be on the lookout for worsening symptoms. Trouble breathing, pain or pressure in the chest, and confusion require immediate medical care.

Even if your antigen test is negative, Roberts advises caution. “I think if you're having signs of respiratory virus infection right now, more likely than not it's COVID,” he says. A PCR test (short for polymerase chain reaction), administered at a doctor’s office or testing site, can confirm your suspicions. Another option to consider if you test negative for COVID-19 but have a fever is a flu test, Washer says, since there are also treatments specific to this illness that can help you feel better.

Preventive measures key in omicron fight

Finally, don’t forget all the preventive efforts that can help you dodge an omicron infection in the first place. Health experts still encourage avoiding crowded gatherings and poorly ventilated indoor spaces. Keep a physical distance between yourself and others not in your household, and wear a mask when you’re out in public.

“One thing I would emphasize is omicron is different than delta, in that even if you're vaccinated, even if you're boosted, you really need to protect yourself by wearing a high-quality mask, especially when you're indoors,” Washer says. The Centers for Disease Control and Prevention has do’s and don’ts for selecting and wearing a mask. With the current surge in COVID-19 cases, many experts are recommending medical-grade masks, such as KN95s and surgical masks, instead of cloth ones.  

When it comes to omicron, “I think we still have a lot to learn,” Washer says.

How to Protect Against the Omicron Variant