RELATED: This One Symptom Could Be Your First Sign of Omicron, Doctors Warn. While the Omicron variant has the ability to spread to both vaccinated and unvaccinated individuals, the way in which it manifests seems to differ. Maya N. Clark-Cutaia, PhD, a professor at the New York University Meyers College of Nursing, told The New York Times that vaccinated patients who get infected with Omicron tend to complain more often of headaches, body aches, and fever. “Like a really bad cold,” she said. On the other hand, shortness of breath, cough, and other common flu-like symptoms are only really hitting unvaccinated individuals infected with this variant. Craig Spencer, MD, the director of Global Health in Emergency Medicine at New York-Presbyterian and Columbia University Medical Center, said that people who have been boosted also might experience sore throat, while those with two-doses might also get fatigue and some coughing. “But no shortness of breath. No difficulty breathing,” he tweeted on Dec. 26. Loss of smell and taste are symptoms that are less common with Omicron across the board. But those with breakthrough cases might also be missing one formerly tell-tale COVID sign: fever. “I think what we are experiencing, though, is for people who are vaccinated, or vaccinated and boosted, we’re not seeing as much fever, if any, as opposed to an unvaccinated person,” Judith O’Donnell, MD, the chief of infectious disease at Penn Presbyterian Medical Center, told The Philadelphia Inquirer. O’Donnell also confirmed that these breakthrough infections are more likely to produce cold-like symptoms. “Vaccinated people who have cold symptoms, nasal congestion, runny noses, sore throats, but aren’t experiencing fever—if you’re vaccinated and boosted, and those are the symptoms you’re having, you may have COVID-19,” she said. RELATED: For more up-to-date information, sign up for our daily newsletter. But many doctors say that the biggest difference vaccinated and unvaccinated people experience with Omicron isn’t the type of symptoms—it’s the severity of symptoms. Peter Chin-Hong, MD, an infectious disease specialist at the University of California, San Francisco, told NBC-affiliate KSN in Wichita, Kansas, that vaccinated and boosted people appear to have less severe symptoms that also last for a shorter amount of time. According to Chin-Hong, unvaccinated people will likely see symptoms for five or more days, while those who are fully vaccinated might only have symptoms for one or two days. “There is little systematic data so far, but I expect that many vaccinated and especially boosted folks are experiencing very mild symptoms,” he said, adding that there is also a “higher proportion of vaccinated folks who have no symptoms.” Preliminary evidence from scientists at Case Western Reserve University has found that the risk of being hospitalized or admitted to the intensive care unit during the U.S. Omicron surge is about half that of what it was during Delta’s height. But it’s still possible, especially among unvaccinated individuals.ae0fcc31ae342fd3a1346ebb1f342fcb “In an unvaccinated person, Omicron is quite capable of and is actually causing pneumonia,” O’Donnell told The Philadelphia Inquirer. “People are coming in [the emergency department] with shortness of breath due to pneumonia, just like it has with prior waves and prior variants.” Daniel Griffin, MD, an infectious diseases specialist at ProHEALTH in New York, recently told NPR that he has also primarily seen unvaccinated people get “more systemic disease like pneumonia” with Omicron. “In fact, I haven’t taken care of any boosted folks in the hospital this time around with COVID, suggesting that they are all outpatients and recovering uneventfully at home,” he said. RELATED: These 4 New COVID Symptoms Could Mean You Have Omicron, Doctors Warn.