COVID symptoms aren’t what they used to be. Here’s how they’ve changed over time, and what they look like now

Sore throat, runny nose, nasal congestion, persistent cough, and headache are now the most common symptoms of COVID among the fully vaccinated, the Zoe Health Study found. The study, run by scientists at Harvard and Stanford universities, is based on data submitted by U.S. and U.K. participants logging in their symptoms via an app for research purposes.

The new symptom list stands in contrast with classic, more severe COVID-19 symptoms such as persistent cough, loss of smell, fever, and shortness of breath that were common at the pandemic’s outset. Such symptoms now rank as No. 5, 6, 8, and 29, respectively, according to the study.

Symptoms that are common presently among those who had one vaccine dose include headache, runny nose, sore throat, sneezing, and persistent cough. Symptoms among the unvaccinated are very similar but include fever instead of sneezing, and a sore throat more often than a runny nose.

Interestingly, those who have been vaccinated and have COVID are more likely to report sneezing than those who have not been vaccinated and have COVID. 

“If you’ve been vaccinated and start sneezing a lot without an explanation, you should get a COVID test, especially if you are living or working around people who are at greater risk from the disease,” the authors wrote.

While COVID patients requiring hospitalization during the Delta wave in late 2021 tended to have pneumonia-like symptoms, COVID patients during the Omicron era more often have symptoms similar to the common cold, according to a June article in Infectious Disease Reports. The four commonly circulating human coronaviruses aside from COVID usually present as common colds.

The shift likely occurred because the Delta variant tended to thrive in the lower respiratory system of those infected, while the Omicron variant, especially more recent strains, tends to thrive in the upper respiratory system. That’s subject to change, however, as the virus evolves.

It’s impossible to say whether Omicron is less severe than Delta, experts say, because the population has continued to build its immunity as the virus evolves. When people are infected or vaccinated, it boosts their immune systems—and while antibody immunity lasts only a few months, T-cell immunity, which can make infections more mild, lasts for much longer. 

It’s possible that COVID is becoming more akin to the seasonal flu, experts say, with more mild, cold-like symptoms and cases that are more common during winter. But it’s too early to tell, they caution, adding that the virus could change course at any point.

Researchers are keeping an eye this fall on strains of COVID that appear similar to Omicron-Delta hybrids, and one, XBC, that’s an actual hybrid of the two, Raj Rajnarayanan, assistant dean of research and associate professor at the New York Institute of Technology campus in Jonesboro, Ark., recently told Fortune.

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