5 Things To Know About the Delta Variant

For the first time in more than a year, we’re feeling some hope—or at least cautious optimism—that the pandemic could recede to the background. But experts want us to know that there is still a concern that new mutations of the virus could bring it back, and it might be even stronger.

A major concern right now is Delta, a highly contagious SARS-CoV-2 virus strain, which was first identified in India in December. It then swept rapidly through that country and Great Britain as well. The first Delta case in the United States was diagnosed in March and it is now the dominant strain in the U.S.

Inci Yildirim, MD, PhD, a Yale Medicine pediatric infectious diseases specialist and a vaccinologist, isn’t surprised by what’s happening. “All viruses evolve over time and undergo changes as they spread and replicate,” she says. 

But one thing that is unique about Delta is how quickly it is spreading, says F. Perry Wilson, MD, a Yale Medicine epidemiologist. Around the world, he says, “Delta will certainly accelerate the pandemic.”  

From what we know so far, people who are fully vaccinated against the coronavirus appear to have protection against Delta, but anyone who is unvaccinated and not practicing preventive strategies is at risk for infection by the new variant, the doctors say.

Here are five things you need to know about the Delta variant.