Symptoms of the COVID-19 Omicron Variant: Here's What We Know

On December 1, 2021—just a few days after the World Health Organization (WHO) declared it a variant of concern—the Omicron variant made its debut in the U.S. with its first confirmed case. And in January 2022, the Omicron variant overtook Delta to become the global dominant COVID-19 strain, according to the WHO.

An April 2022 study published in Signal Transduction and Targeted Therapy found that Omicron has more than 30 mutations in the spike gene—the part of the virus that allows it to penetrate your cells and infect you—and it's likely more transmissible than the original SARS-CoV-2.

When a new variant emerges, many questions arise about how it may differ from previous variants, including what symptoms it causes and whether it's more or less likely to cause severe illness. Here's what we know so far about the symptoms of the Omicron variant, according to research and infectious disease experts.

What Are the Symptoms of the Omicron Variant?

The symptoms of the Delta variant are often like those of a very bad cold. Based on a ZOE Health Study analysis of COVID-19 symptoms among infected people in London, the symptoms of the Omicron variant might not be too different.

That study compared the COVID-19 symptoms that people recorded during a week in October—before the Omicron variant was known to be in London—and a week in December—after the variant was confirmed to be in London. During both weeks, the top five symptoms people reported were runny nose, headache, fatigue, sneezing, and sore throat.

"Hopefully, people now recognize the cold-like symptoms which appear to be the predominant feature of Omicron," Tim Spector, lead scientist of the study app behind the data, the ZOE COVID Study app, said in a press release.

"As our latest data shows, Omicron symptoms are predominantly cold symptoms, runny nose, headache, sore throat, and sneezing, so people should stay at home as it might well be COVID," Spector said.

Other common symptoms include nasal congestion, a dry cough, and aches (particularly lower back pain).

In the December 17, 2021, issue of Morbidity and Mortality Weekly Report, the Centers for Disease Control and Prevention (CDC) released an analysis of the first 43 cases of the Omicron variant that were reported in the U.S. That research showed that the most commonly reported symptoms among those patients were cough, fatigue, and congestion or runny nose.

So Does the Omicron Variant Only Cause Mild Symptoms?

A May 2022 review published in Medicine found that the Omicron variant causes far less severe infections compared to Delta and other variants. Data from the ZOE COVID Study app found that those infected during the Omicron wave were 25% less likely to be admitted to the hospital than patients infected during the Delta wave.

While Omicron symptoms appear to be milder, Maria Van Kerkhove, the WHO's COVID-19 technical lead, said that Omicron symptoms can still vary widely.

"We know that people infected with Omicron can have the full spectrum of disease, from asymptomatic infection to mild disease, all the way to severe disease to death," Van Kerkhove said during a question-and-answer session, per CNBC.

Plus, it's still not yet clear whether Omicron truly causes "milder" symptoms than other strains. According to Mohammad Sobhanie, MD, an infectious disease physician at The Ohio State University Wexner Medical Center, it is possible that Omicron could result in different or milder symptoms than previous variants.

But that may have more to do with people's vaccination status than the virus itself—because more people than ever are vaccinated, it's possible Omicron just seems milder.

Being fully vaccinated, and especially boosted, reduces the chances a person will experience any COVID-19 symptoms at all—but as we've learned by now, it's possible to get a breakthrough infection, or an infection when you're fully vaccinated or even boosted, according to the CDC.

When fully vaccinated and boosted people experience COVID-19 symptoms, they may be milder and shorter in duration, Dr. Sobhanie said. "We know that even with breakthrough infections, vaccinated people are less likely to get sick, and if they do get sick, they have a far lower chance of hospitalization and death," Dr. Sobhanie added.

Also, early outbreaks of Omicron have been among young adults who tend to have milder infections anyway, as well as among those who are more likely to have antibody protection through vaccination or previous infection, Anne Liu, MD, an infectious disease physician with Stanford Health Care, told Health.

It's also important to keep in mind that with every new variant, there's a lag between infections and hospitalizations, so a variant can initially seem less concerning than it actually may be.

"Whenever there is a new variant, people say cases are going up but not hospitalizations, but we seem to forget that there's a lag of several weeks before we know if these cases will result in more hospitalizations and deaths," Dr. Liu said.

More data is needed to conclude if Omicron infections cause more severe illness or death compared to infections with other variants and how effective vaccines are against severe illness, hospitalizations, and deaths.

To gather more information, the CDC is closely monitoring real-world vaccine effectiveness and breakthrough infections, as well as Omicron's impact on disease incidence, severity, and vaccine breakthrough.

How Can I Protect Myself Against Omicron?

Experts continue to learn more about the Omicron variant and its specific risks (including any new symptoms, especially in unvaccinated people, and how much protection the vaccines provide).

But it's important to be aware of existing COVID-19 symptoms and to stay home if you feel ill (even if it just seems like you have a cold). The CDC says COVID-19 may cause the following symptoms:

• 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

To protect yourself and others from severe sickness from any COVID-19 strain, Dr. Liu said the best thing to do is get fully vaccinated. And if you're already fully vaccinated, getting booster shots can provide further protection. If you have children who are eligible, it may be best to prioritize getting them vaccinated also.

Even if you're fully vaccinated, the CDC recommends wearing a mask in indoor public transportation settings, but you can choose to wear a mask at any time. If you're getting together with people you don't live with, then Dr. Liu suggests everyone take a rapid COVID-19 test at home to prevent asymptomatic spread (ideally, take a rapid test the same day of the gathering).