(NEXSTAR) – In the month and a half since omicron started spreading across the U.S., we’ve learned a lot about what the variant looks and feels like. For many, especially the vaccinated, it seems to feel more like a bad cold than influenza or severe respiratory illness.

While there haven’t yet been any major peer-reviewed studies of omicron symptom differences between vaccinated and unvaccinated people, doctors are reporting anecdotal evidence that show some differences.

Dr. Maya N. Clark-Cutaia, professor at the New York University Meyers College of Nursing, described the differences she’s seeing in patients to the New York Times. Vaccinated people are reporting headaches, body aches and fever when infected with omicron, she said. Unvaccinated patients are more frequently reporting cough, shortness of breath and flu-like symptoms.

Dr. Judith O’Donnell, chief of infectious disease at Penn Presbyterian Medical Center, told the Philadelphia Inquirer her hospital was also seeing unvaccinated patients coming in with pneumonia and shortness of breath – more urgent problems commonly associated with delta and past variants.

The biggest difference between vaccinated and unvaccinated people isn’t with the types of symptoms – it’s with the severity of symptoms.

“There is little systematic data so far, but I expect that many vaccinated and especially boosted folks are experiencing very mild symptoms and there is a higher proportion of vaccinated folks who have no symptoms,” said Dr. Peter Chin-Hong, an infectious disease specialist at the University of California, San Francisco.

Chin-Hong said he also has noticed that vaccinated and boosted people are experiencing symptoms for a shorter period of time, sometimes one or two days instead of the five or more days more typical of a case in an unvaccinated person.

“It just seems that people who have been vaccinated ahead of time are getting much milder symptoms across the board,” agreed Dr. Daniel Griffin, chief of infectious diseases at ProHEALTH in New York, in an interview with NPR.

“In the hospital, I have seen primarily unvaccinated folks get more systemic disease like pneumonia,” he said. “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.”

That’s why staying up to date on COVID-19 shots is so important, doctors emphasize. While breakthrough cases of omicron have been pretty common, less severe disease means fewer hospitalizations and deaths.