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Are Delta Variant’s Different Symptoms Related to COVID Vaccine?

June 16, 2021

Does the Delta variant sweeping through the United Kingdom and rapidly increasing in the United States actually represent a victory for the COVID-19 vaccine?

The new strain, now linked to 90 percent of UK cases and 10 percent of U.S. cases, is associated with a different set of symptoms, including headache, sore throat and runny nose. In the past, COVID patients typically reported cough, fever and loss of taste and smell as primary symptoms.

“The majority of the UK has been vaccinated,” says Dr. Ulysses Wu, Hartford HealthCare’s System Director of Infection Disease and Chief Epidemiologist, “and the reason we’re seeing different symptoms over there is because the vaccine is doing exactly what it’s supposed to do. It’s supposed to take a potentially lethal disease that causes systemic fever, cough and respiratory failure and turn it into a cold.”

Yet the new strain, which has delayed the UK reopening, is more contagious than the original and more likely to require hospitalization among the unvaccinated. It’s considered 60 percent more transmissible that a previous variant firsts detected in the UK, the World Health Organization said Friday.  The WHO also said the Delta variant is becoming the dominant COVID variant worldwide.

In the UK, younger adults awaiting vaccination and others susceptible to symptomatic infection have been urged to remain home and get tested if they feel ill. Even if unvaccinated, however, younger people would likely avoid serious illness from the Delta variant.

“The older you get,” says Dr. Wu, “the more your immune system is going to wane. You’re not going to be able to fight things off as best as possible. And, so, yes, younger people are probably having these (milder) symptoms. We know that children are more likely to not have any symptoms at all and possibly be asymptomatic carriers, but I don’t think it’s necessarily a genetic predisposition of age that says you’re going to have different symptoms.”

The Delta variant, first identified in India, has almost doubled every two weeks in the United States as more states lift all COVID-related safety precautions. A previous variant, Alpha, discovered in the UK followed a similar progression.

Alpha represented almost 70 percent of U.S. cases through May, according to the Centers for Disease Control and Prevention, up from 26 percent in mid-March.

Here is Delta’s timeline in the US, in percent of cases:

  • Mid-April: 0.6 percent.
  • Early May: 1.3 percent.
  • Mid-May: 2.5 percent.
  • Now: about 10 percent.

The CDC has upgraded Delta to a variant of concern, placing it in the same level of surveillance as Alpha and Gamma, the variant first identified in Brazil.

If you’re vaccinated, any COVID variant is unlikely to require hospitalization. Anyone unvaccinated, however, faces an increased risk of serious illness.

“This has always been the purpose of vaccines,” says Dr. Wu. “It’s not necessarily to prevent disease, but take a potentially lethal disease and turn it into something more or less benign like a common cold.”