HOUSTON - With COVID-19 vaccination rates slowing down, some experts worry herd immunity is out of reach anytime soon.
But, Dr. James McDeavitt with Baylor College of Medicine says he's more optimistic than others.
"The vaccination story in the US, to date, has been a success. We've vaccinated 243 million people," he told FOX 26.
He says at Baylor College of Medicine they went from 300-400 vaccinations a day to just a couple dozen earlier this week. But, he feels that is expected and happening in other countries with robust vaccination efforts.
He explains he is hopeful because of what is happening in Israel.
"It was right around 50 percent immunity that they saw their numbers drop," Dr. McDeavitt pointed out.
He notes, so far, in Israel, about 63 percent of the population has at least one dose of a COVID-19 vaccine and there are about 7 new cases per million a day.
In the US, about 45 percent of the population has at least one dose and there are 141 new cases per million a day.
For perspective, he says in India about 10 percent have received at least one dose and there are 280 new cases per million a day.
He believes the U.S. is closer to 60 percent immunity. He is taking into account the 32 million cases and, he says, it is reasonable to assume another 32 million were likely infected but were unaware because they were asymptomatic.
"North of 50 percent -- 51, 52 percent of the US population has been vaccinated or infected at this point," Dr. McDeavitt said.
But there is a major concern -- variants. The fewer people are vaccinated, the more opportunity the virus has to mutate.
"It's sort of a matter of time," he warns. "There have been trillions of opportunities for the virus to mutate eventually it's going to produce one that is resistant to vaccines and that creates another spread of the virus and it becomes more problematic. So, it's kind of the reason why there's a sense of urgency to get this behind us and get people vaccinated as quickly as possible."