What Is the Delta Plus Variant? Here’s What Experts Know About It So Far

What Is the Delta Plus Variant? Here’s What Experts Know About It So Far
  • Public health officials in South Korea have reported the country’s first two cases of the Delta Plus coronavirus variant.

  • Delta Plus is a sub-lineage of Delta, the highly contagious variant responsible for a majority of new COVID-19 cases in the U.S.

  • Here’s what infectious disease experts know about Delta Plus so far, including where it has been detected.


Public health officials in South Korea have reported the country’s first two cases of the Delta Plus coronavirus variant. The variant, which is a mutation of the highly contagious Delta variant responsible for the recent surge in U.S. COVID-19 cases, was first identified in India.

“The first case [in South Korea] was identified in a man in [his] 40s who has no recent travel records,” the Korea Disease Control and Prevention Agency (KDCA) told Reuters. It’s unclear how the man became sick. The second case of Delta Plus was in a traveller who recently returned from the United States. That patient had been vaccinated with both doses of the AstraZeneca vaccine.

Delta Plus started trending on Twitter soon after the news broke, with plenty of people expressing worry about what this means for the future of the COVID-19 pandemic. Unfortunately, there’s a lot public health experts don’t know about Delta Plus—but there is some information as it continues to be monitored.

What is the Delta Plus variant, exactly?

Delta Plus is a sub-lineage of the Delta variant. The original Delta variant has several mutations on its spike protein that make it more transmissible, according to the Centers for Disease Control and Prevention (CDC), which lists Delta as a “variant of concern.” It also has the potential to reduce the effectiveness of some monoclonal antibody treatments and may partially evade the COVID-19 vaccine.

“This mutation is seen in some but not all of the Delta variants,” says David Cennimo, M.D., assistant professor of medicine-pediatrics infectious disease at Rutgers New Jersey Medical School. “It is a variation of the variant, if you will.”

Delta Plus has a spike protein mutation called K417N, which is also found in the Beta variant that was first detected in South Africa, says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. “There are countless variants but only specific ones are tracked or labeled of interest or concerns,” he says. “Delta Plus is listed as a variant of concern by the WHO and CDC—under its technical name AY.1—and aggregated with Delta.”

Theoretically, the mutation “could make [Delta Plus] even more infectious than Delta—and Delta is already highly adept at infecting people,” Dr. Cennimo says.

Where has Delta Plus been reported?

This isn’t the first time Delta Plus has been detected. There have been a few cases in the U.K., Portugal, and India, per Reuters. It has been detected in the U.S., according to The New York Times, and may be in a dozen countries.

Delta Plus was first detected in April in India’s state of Maharashtra, where it’s been declared it a “variant of concern,” the Times reports.

What are the symptoms of Delta Plus?

As of now, they seem to be the same as the symptoms of the Delta variant and earlier coronavirus strains, says John Sellick, D.O., an infectious disease expert and professor of medicine at the University at Buffalo/SUNY. According to the CDC, those include but are not limited to:

  • Fever or chills

  • Cough

  • Shortness of breath or difficulty breathing

  • Fatigue

  • Muscle or body aches

  • Headache

  • New loss of taste or smell

  • Sore throat

  • Congestion or runny nose

  • Nausea or vomiting

  • Diarrhea

How worried should you be about Delta Plus?

Experts are still trying to figure that out. “We’re not entirely sure what it means yet,” says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. “Are there things about this Delta Plus variant that are different? Is it transmitted more or less frequently than the Delta variant? Is it more or less contagious and, critically, is it a variant that is only partially protected by our current vaccines? None of these questions have been answered yet. It’s early days.”

Dr. Adalja agrees. “There’s no specific concern with this variant yet, over and above the concern with Delta,” he says, adding that it’s “unclear” if the mutation will do anything to change the state of current COVID-19 cases.

“We have to step back a bit and say, ‘Let’s see how this develops,’” Dr. Sellick adds. “We’re not going to modify our treatments and vaccines based on a few cases.”

That said, it’s important for the public health community to track Delta Plus. “We don’t want to ignore it or blow it off,” Dr. Sellick says. “If it becomes dominant, it becomes an issue.”

This article is accurate as of press time. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus develops, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news. Always talk to your doctor for professional medical advice.

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