As confirmed daily coronavirus cases remain over 50,000 and certain localities face new surges, a doctor stressed that new virus mutations could prolong the pandemic.

“The thing that worries me is that there are still so many infections that we give the virus an opportunity to mutate,” Dr. Jeremy Faust, an emergency medicine physician at Brigham & Women’s Hospital, said on Yahoo Finance Live (video above). “Once in a while, one of those mutations does crop up in a way that can hurt us. So what I keep hoping that I won’t wake up and read in the next paper is that now I’ve got one that’s 10 times worse or one that hits kids harder.”

The current 7-day average for hospitalizations in the U.S. is at 5,631, a 1.6% increase from the prior week. The CDC noted that while hospitalizations have declined since their peak in January 2021, they have been steadily increasing since March 22.

“As we move through the population and vaccinate more people, there’s a point there that at some point, if I get a mild case of COVID but I don’t really notice it, then my case doesn’t really matter,” Faust said. “As long as I’m not spreading it to others, who could be harmed? So for me, a really good metric to watch is hospitalizations. Hospitalizations give you a pretty good sense of how people are doing in the community.”

The more people who are not vaccinated, the more infections we have’

Nearly 90 million American adults are fully vaccinated, while roughly 135 million have received at least one dose. For the U.S. to reach herd immunity, an estimated 75-80% needs to be fully vaccinated.

“Herd immunity is going to be a moving target because natural immunity could wane,” Faust said. “We don’t know how long the vaccine immunity will last, although I’m pretty optimistic it will last a while. To me, the way you know you’re at a place where you can return to normal is if our rates of flu-like illnesses and COVID-like illnesses are close to our historical norms — not the norms of the last 15 months. I want to see a sustained low level of hospitalizations.”