Although "hallmark signs" of Covid-19 include loss of taste and smell, fever, cough, shortness of breath, and fatigue, early data suggests that those infected with the highly contagious delta variant may have different symptoms.

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A potential change in symptoms?

As the delta variant has become more widespread over the past several months, however, there are more reports of cases with primary symptoms including headache, sore throat, and runny nose, reports Christina Caron for the New York Times.  

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"All those are not the old classic symptoms," said Tim Spector, leader of the ZOE Covid Symptom Study, which collects information from millions of participants in Britain, the United States, and Sweden. He added that cough fell to fifth on the list of the most commonly reported symptoms, and "we don't even see loss of smell coming into the top 10 anymore."

It's unclear whether the change in symptoms is due to the delta variant. Still, according to Spector, the available data suggests Covid-19 is "acting different now. It's more like a bad cold in this younger population."

Andrew Chan, an epidemiologist at Massachusetts General Hospital and one of the ZOE study's lead investigators, said the symptoms in breakthrough infections among vaccinated adults in particular "are much more commonly identified with the common cold."

Similarly, Joe Kanter, Louisiana's state health officer, told a New Orleans radio station that many Covid-19 patients are now developing symptoms that may be mistaken for allergies or the common cold, MedPage Today reports.

"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 said.

However, some pediatricians say the Covid-19 symptoms they are seeing in children now are largely the same as they've been since the pandemic began. According to Sallie Permar, pediatrician-in-chief at NewYork-Presbyterian Hospital and Weill Cornell Medicine, the "classic presentation of Covid" symptoms among children include fever, cough, fatigue, headache, and sore throat.

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Currently, more severe cases of Covid-19 are more common among adolescents who are unvaccinated, particularly those who have other underlying conditions, like diabetes or obesity, the Times reports.

Get tested if you're unsure, experts say

So far, experts have been cautious about offering any concrete conclusions about the delta variant's effect, especially as much of the data and reports have been primarily anecdotal.

"I don't think with what we know right now that we can conclude [delta] is much different in terms of symptoms," David Kimberlin, a pediatric infectious diseases expert at the University of Alabama at Birmingham, said. "There have been some reports that it causes more cold-like illness, but so did the original [coronavirus]. I think we'll know more over the next couple of months as we have the opportunity to realize the data."

Experts recommend that people get tested if they or their children are experiencing potential symptoms of Covid-19 or even a cold.

"If you aren't sure, I do recommend Covid testing," Purvi Parikh, a physician at NYU Langone Health and a spokesperson for the American College of Allergy, Asthma & Immunology, said.

Kimberlin agreed, especially for fully vaccinated people who may be more likely to have mild symptoms if they are infected.

"If you have mild cold-like symptoms, you should go get tested," Kimberlin said, noting that testing is especially important for people routinely in contact with vulnerable populations, such as young children, older parents, or long-term care residents. "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."

"It’s a time to be humble about the fact that this is a new variant. We're still learning," Mark Mulligan, director of the NYU Langone Vaccine Center and chief of infectious diseases at NYU Langone Health, said. "Be cautious and err on the side of caution in terms of going ahead and getting a test." (Caron, New York Times, 8/15; Fiore, MedPage Today, 8/11)