Are COVID Symptoms Different With Delta?

Questions about whether COVID symptoms are different with Delta compared with earlier variants have been raised again, after a Louisiana public health official recently said patients are presenting with more mild symptoms.

Louisiana’s State Health Officer Joe Kanter, MD, MPH, told a local New Orleans radio station that many COVID patients are now developing symptoms that can be mistaken for other illnesses like allergies or the common cold.

“You can present with relatively mild symptoms that you can easily confuse for allergies or something that you picked up from your kid who is in daycare, all of those things,” Kanter told WWL. “If you have any symptoms, no matter how mild, even if it is a sore throat, even if it is a runny nose, even if it is sinus congestion, go get yourself tested and limit your contact with other people until you do so.”

While there haven’t been many data on differences in COVID symptoms with Delta, the idea appears to originate with the leader of the ZOE COVID Symptom Study in the U.K.

Back in June, ZOE study leader Tim Spector, MB, MSc, MD, of King’s College London, said in a YouTube video that data collected by his app suggest COVID is “acting different now. It’s more like a bad cold in this younger population.”

At that time, the most commonly reported symptoms had changed to headache, followed by sore throat, runny nose, and fever.

“All those are not the old classic symptoms,” Spector said, adding that cough fell to fifth on the list, and “we don’t even see loss of smell coming into the top 10 anymore. This variant seems to be working slightly differently.”

Certainly Spector’s report is limited by the fact that it’s relying on self-reported data, and his findings were not part of any peer-reviewed literature; they didn’t even appear in any preprint publication.

But other experts have acknowledged an uptick in anecdotal reports about COVID symptoms now being different from those seen with previous variants.

David Kimberlin, MD, a pediatric infectious diseases expert at the University of Alabama at Birmingham, has heard those reports, but remained cautious about interpreting them.

“I don’t think with what we know right now that we can conclude [Delta] is much different in terms of symptoms,” Kimberlin told MedPage Today. “There have been some reports that it causes more cold-like illness, but so did the original COVID. I think we’ll know more over the next couple of months as we have the opportunity to realize the data.”

Purvi Parikh, MD, of NYU Langone in New York City and a spokesperson for the American College of Allergy, Asthma & Immunology, has also heard anecdotal reports about mild COVID being mistaken for allergies, but noted that allergy would be unlikely to come with features such as high fever, nausea, vomiting, or diarrhea.

Other symptoms that would make it unlikely to be allergies include myalgia and chills, said Alan Goldsobel, MD, of Allergy & Asthma Associates of Northern California, who is also a professor at Stanford University. Giveaways that it’s just allergies would be the time of year (for those with seasonal allergy), as well as itching, he added.

It could be more difficult to distinguish COVID from common cold symptoms, Parikh and Goldsobel noted.

“If you aren’t sure, I do recommend COVID testing,” Parikh said.

Kimberlin agreed, especially for fully vaccinated people who’ve been hearing that they may be more likely to have mild illness if they are indeed infected.

“If you have mild cold-like symptoms, you should go get tested,” especially if you have contact with vulnerable populations like young children, older parents, or long-term care residents, he said. “The best way we can protect them is to be vaccinated ourselves, and then know if we’re infected — even if we’re not getting very sick because we’ve been vaccinated.”