The United States is now recording about 20,000 new coronavirus cases per day as the more contagious Delta variant overtakes the original strain of the virus. And while experts say that states like Massachusetts with high vaccination rates are at less of a risk, other regions with low vaccination rates are seeing spikes in their COVID-19 numbers, prompting chief White House medical adviser Dr. Anthony Fauci to warn that the resulting difference will almost look like “two Americas.”

Jim Braude was joined on Greater Boston by Dr. Nahid Bhadelia, founding director of Boston University’s Center for Emerging Infectious Diseases Policy & Research; and Dr. Mark Siedner, an infectious disease clinician and researcher at Mass General's Division of Infectious Diseases.

According to CDC data, Bhadelia noted, 99% of COVID-19 deaths now are among the unvaccinated, yet Massachusetts hasn’t seen an increase in cases because of high vaccination rates. But that doesn’t mean the Delta variant is not a threat. “Here I worry about inequity in terms of pockets or entire communities that may still be unvaccinated,” she said. “That’s where, within a state like ours that’s highly vaccinated, those are the areas that you might see surges in cases and potential hospitalizations.”

With the Delta variant spreading in less-vaccinated states, should Massachusetts worry about people crossing borders? Not for now, said Siedner. “As long as we continue high vaccination rates in this state, we will be lucky — because we are approaching something like herd immunity in this state.” However, he said, Massachusetts should keep an eye on whether the Delta variant continues to spread in other regions. “It is in our interest to make sure that people around this country and around the world get vaccinated even if we have high rates here.”

WATCH: What does the Delta variant mean for Massachusetts?