5 Things You Need to Know About the Delta Variant, According to Doctors

There's much still to learn, but here's what experts know about the powerful Delta variant.

Since dampening the collective hope that the COVID-19 pandemic was on its way out the door when it arrived earlier this summer, the Delta variant continues to cause problems in certain parts of the United States. It remains the dominant strain of coronavirus in the U.S., accounting for 99 percent of new cases, The Washington Post reported recently, and has caused significant surges in new cases and hospitalizations in certain states. And while there is still much to be learned about the highly transmissible virus strain, there are certain key characteristics that experts say are important to understand. Read on to discover five things doctors say you need to know about the Delta variant.

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It is much more contagious than previous strains of coronavirus.

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One of the biggest concerns about the Delta variant is that it seems to be far more contagious than previous strains of the virus. In fact, according to F. Perry Wilson, MD, a Yale Medicine epidemiologist, at one point Delta was spreading 50 percent faster than the Alpha variant, which was 50 percent more contagious than the original strain of COVID-19.

"In a completely unmitigated environment—where no one is vaccinated or wearing masks—it's estimated that the average person infected with the original coronavirus strain will infect 2.5 other people," Wilson says. "In the same environment, Delta would spread from one person to maybe 3.5 or 4 other people."

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It can cause even more severe illness than previous versions of the virus.

A young woman who appears to be having COVID symptoms sitting in bed while checking a thermometer

In addition to being more transmissible than earlier strains of the virus, Delta variant also can cause more severe symptoms according to Mira Irons, MD, chief health and science officer at the American Medical Association (AMA).

"We know that it appears to be both more contagious and more severe than earlier versions of the virus," Irons explained during an episode of AMA COVID-19 Update. "We're seeing patients becoming sicker and their conditions are worsening much more quickly."

Younger people seem to be at an increased risk.

group of elementary school students in the classroom during the covid-19 pandemic, wearing face masks and standing six feet apart, social distancing.

According to Inci Yildirim, MD, PhD, a Yale Medicine pediatric infectious diseases specialist and vaccinologist, research shows that children and adults under the age of 50 were 2.5 times more likely to become infected with Delta than previous versions if they are unvaccinated.

"As older age groups get vaccinated, those who are younger and unvaccinated will be at higher risk of getting COVID-19 with any variant," she says. "But Delta seems to be impacting younger age groups more than previous variants."

It may not present all the same symptoms caused by previous strains.

A woman sitting on the couch while sick and blowing her nose into a tissue while holding a mug

While there is still much to be learned about the Delta variant, doctors and other experts have noted that while some symptoms are similar to the ones commonly associated with previous strains of coronavirus, others appear to be less common in Delta infections.

"It seems like cough and loss of smell are less common," Yildirim says. "And headache, sore throat, runny nose, and fever are present based on surveys in the U.K."

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Vaccines are effective at providing protection.

Covid-19 Vaccination. General Practitioner Vaccinating Older Female Patient Against Coronavirus With Antiviral Vaccine, Sticking Medical Adhesive Bandage On Arm After Injection In Centre Clinic

While the Delta variant is certainly more transmissible than previous versions and even some vaccinated people have been infected with the virus, generally speaking, doctors seem to agree that currently available COVID-19 vaccines provide a substantial level of protection and help slow the spread of the virus.

"Viral variants occur when the virus is transmitted and reproduces itself. COVID-19 vaccines are key to controlling the pandemic and to prevent future variants from developing," Roy M. Gulick, MD, chief of the Division of Infectious Diseases at NewYork-Presbyterian/Weill Cornell Medical Center and Weill Cornell Medicine, said in an interview with Health Matters. "Current vaccines are highly effective and not only prevent infection, but they also effectively reduce transmission to others."

However, it is important to have had both doses of a vaccine to ensure optimal protection, says Sandra Fryhofer, MD, an Atlanta general internist and the AMA's liaison to the CDC's Advisory Committee on Immunization Practices (ACIP).

"Even though this variant is hyper transmissible, a full vaccination series seems to protect against it, but you need both doses of a two-dose series—one mRNA vaccine dose may not be enough," she says.

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