The Delta variant has managed to quickly reverse the major progress the U.S. had made toward ending the COVID-19 pandemic. The strain has spread quickly across the country, pushing the national daily case average above the highest point recorded last summer. Unfortunately, mounting data also shows that the variant can cause rare breakthrough infections in fully vaccinated people, even though the risk of severe disease or death is almost entirely eliminated, according to Centers for Disease Control and Prevention (CDC) data. Now that vaccinated people are on high alert again about contracting the virus, it’s time to get reacquainted with the symptoms of COVID, especially because some have changed, potentially due to the Delta variant. And there are also some differences in COVID symptoms among unvaccinated versus vaccinated people. The signs that you’re sick with the virus can even change based on how many shots you’ve received, according to data from the ZOE COVID Symptom Study in the U.K.
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Researchers with the ZOE COVID Symptom Study have been collecting data on the virus through an app launched in March 2020 where Brits track their own symptoms. In a report released on June 23, by which point the Delta variant had become dominant in the U.K., they said recent information showed slight differences in symptoms between unvaccinated and vaccinated patients—and in some cases, even between those with one shot versus two.
There were three symptoms all patients commonly reported, no matter their vaccination status: headache, runny nose, and a sore throat were the top symptoms among vaccinated people, partially vaccinated people, and unvaccinated people. But beyond that, things diverged. For example, unvaccinated patients were more likely to report a fever, while patients who’d been vaccinated, whether partially or fully, were more likely to report sneezing. Additionally, patients who hadn’t gotten vaccinated and those with only one shot reported a persistent cough more often than fully vaccinated people. Interestingly, fully vaccinated patients were the only group who regularly experienced a loss of smell in their top five symptoms.
“There are a few reasons why symptoms may be changing, including the fact that those who have been vaccinated experience less severe symptoms, as well as more cases being reported by younger people, who we have found experience different, less severe symptoms as well,” the researchers wrote in their report.
The researchers also point out that the data comes from experiences reported in the app alone. The symptom rankings also don’t consider which variant is responsible for each infection or the demographic information of the patients in question, though Delta was becoming increasingly prominent as they conducted this research.
However, the team also points out that the latest findings could still be a useful way to see if you’ve fallen ill. “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,” they suggest.
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An internal CDC document recently obtained by The Washington Post also found that both unvaccinated people and vaccinated people with COVID had similarly high levels of virus in their bodies that potentially made them contagious. (Previously, medical experts believed breakthrough cases would carry a lower viral load, but real-word data has shown that not to be the case.)
While the Delta variant may be making headlines for occasionally evading the protection afforded by the shots, experts point out that data still overwhelmingly supports being fully vaccinated as the best defense against the Delta variant.
“Like everything in life, this is an ongoing risk assessment,” Inci Yildirim, MD, a Yale Medicine pediatric infectious disease specialist, said in a statement on July 30. “If it is sunny and you’ll be outdoors, you put on sunscreen. If you are in a crowded gathering, potentially with unvaccinated people, you put your mask on and keep social distancing. If you are unvaccinated and eligible for the vaccine, the best thing you can do is to get vaccinated.”
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