“It’s not the same disease that we were seeing with delta and previous variants,” said Dr. John Swartzberg, clinical professor emeritus of infectious diseases and vaccinology at UC Berkeley.

UC Berkeley infectious disease expert Dr. Swartzberg said this study confirms what clinicians are seeing. Telltale features of how the virus infects the human body with omicron versus delta.

VIDEO: Scientists explain why getting infected with omicron doesn’t protect you from other variants of COVID

“People infected with omicron tend to have more upper respiratory illnesses. Nose, throat, more upper respiratory congestion. People who had delta in previous infections had more systemic symptoms like fever, body aches,” Dr. Swartzberg said.

The study by researchers from UCSF, the Chan Zuckerberg Biohub, and the Latino Task Force found that the most common symptom while on omicron was cough, followed by sore throat, congestion, and very rarely loss of smell or taste.

“If you’ve been boosted, ironically you have more upper airway congestion, like the nose is more stuffy. If you’ve been boosted, you’ve just had a few mRNA bites or if you haven’t been vaccinated at all, you didn’t necessarily have as much upper respiratory congestion, but you were sicker in terms of fever and body aches,” Dr. Swartzberg said.

The Latin Working Group played a key role in collecting this data. They followed those who tested positive at their Mission testing site and tracked their symptoms.

VIDEO: Here’s why some people still get COVID even after being vaccinated and double-boosted

“One thing also that we found with omicron is that at the end of the recommended five days of isolation, most people were still positive. So the importance of continuing to test is very high,” said said Susan Rojas of the Latino Task Force.

Their data also revealed that fevers were “less common in people who received boosters than in unvaccinated people or those who received the primary series.”

“What we can infer is that those who are boosted had significantly more symptoms of congestion. Which means the immune system was recognizing the virus much faster and making it more difficult for it to progress,” Rojas said.

This study is awaiting peer review.

RELATED STORIES AND VIDEOS: