As of June 13, about 10% of COVID-19 cases in the U.S. have been identified as the delta variant, a mutation first detected in India. Scientists are still trying to figure out just how dangerous it is.
The delta COVID-19 variant, also known as B.1.617.2, is now the dominant variant in India and in the U.K., and cases are rising in the U.S., with its case share more than doubling in the last couple of weeks, from 3% to 10%.
The delta variant was the main culprit during India’s record breaking COVID-19 surge earlier this spring. The variant is also responsible for a new surge in cases in the U.K., which is expected to delay the lifting of restrictions.
Former FDA chief Dr. Scott Gottlieb said on Sunday that the delta variant will likely become the dominant strain in the U.S., and could lead to more outbreaks for unvaccinated people this fall.
“Right now, in the United States, it’s about 10% of infections. It’s doubling every two weeks,” Gottlieb told “Face the Nation.” “That doesn’t mean that we’re going to see a sharp uptick in infections, but it does mean that this is going to take over. And I think the risk is really to the fall that this could spike a new epidemic heading into the fall.”
Here’s a look at what we know -- and what we don’t know -- about the delta COVID-19 variant:
What is the delta variant and where did it come from?
The delta variant was first detected in India in October 2020. It’s listed as a “Variant of Concern” by the World Health Organization.
The variant is just one of the many mutations detected during the COVID-19 pandemic, joining at least eight other detected variants around the world. Virus mutations are expected and are part of the natural progression of viruses as a survival tactic.
Is the delta variant more dangerous than others?
The short answer is -- we’re not sure yet. But there’s some early evidence to suggest it could be.
Health officials in the U.K. have said that they believe the delta variant is “significantly more transmissible” than the Alpha variant (B.1.1.7, U.K.). The variant now accounts for more than 90% of new cases in the U.K.
Some researchers believe it’s the most contagious variant we’ve seen so far, but others are interpreting the early data more cautiously, noting that human behavior and relaxed restrictions around the world could also be propelling spread.
“Preliminary results say you do see this increased transmissibility, but we still need to collect more information,” Nevan Krogan, a molecular biologist at the University of California, San Francisco, told ABC News. “We need more data, and not just tracking and epidemiology data, but we also need molecular data,” Krogan said. “The more we understand about this virus and how it mutates, the better off we’re going to be in the future.”
Still, doctors on the ground are reporting more serious symptoms and cases. In China, doctors have reported patients getting sicker much faster, as well as developing different symptoms, like stomach pain, nausea, joint pain and even hearing loss. But more data is needed.
U.K. data suggests the Delta variant could cause an increased risk of hospitalization in comparison to the Alpha strain, according to Public Health England (PHE).
Are vaccines effective against the delta variant?
Researchers in the U.K. found that vaccine effectiveness against the delta variant was about the same for Pfizer or Moderna vaccines -- which is really high, about 88% for Pfizer. The AstraZeneca vaccine was 60% effective two weeks after the second dose.
Researchers noted that the second dose of the two-dose vaccine was extremely important for building protection against the delta variant. “We expect the vaccines to be even more effective at preventing hospitalization and death, so it is vital to get both doses to gain maximum protection against all existing and emerging variants,” said Dr. Mary Ramsay, Head of Immunization at Public Health England.
“The mRNA vaccine seems to be highly effective, two doses of that vaccine against this variant. The viral vector vaccines from J&J and AstraZeneca also appear to be effective, about 60% effective. The mRNA vaccines are about 88% effective,” Gottlieb said, referring to the vaccines developed by Moderna and Pfizer/BioNTech. “So we have the tools to control this and defeat it. We just need to use those tools.”
Bottom line: Get vaccinated.
Will the virus keep mutating?
Yes. That’s what viruses do! That’s how they’ve survived for billions of years.
According to an article published in the Journal of Virology, about 8 percent of human DNA comes from viruses inserted into our genomes in the distant past, in many cases into the genomes of our pre-human ancestors millions of years ago. Most of these viral genes come from retroviruses, RNA viruses that insert DNA copies of their own genes into our genomes when they infect cells.
Viruses constantly change through mutation, and new variants of a virus are expected to occur over time.