Highly Contagious Delta Variant​ Could Cause Next COVID-19 Wave: 'This Virus Will Still Find You'

Whether it's airports, NBA games, or concerts, crowds are gathering across the nation as Americans start a return to pre-pandemic life.

But with just 45% of Americans fully vaccinated and only 16 states that have fully vaccinated more than half of their populations, health experts are worried about the spread of the highly contagious Delta variant. It is 60% more contagious than the Alpha variant discovered in the U.K., which was the last variant of major concern, according to infectious disease expert Michael Osterholm.

"In the areas where they have large pockets of unvaccinated people, we can surely expect to see surges in cases, in some situations challenging the health care capacity of that local area," Osterholm told CBS News' David Begnaud.

A hospital dealing with an overfill of patients is Mercy Hospital in Springfield, Missouri. Mercy Hospital President Craig McCoy said the hospital is "holding patients in the ER, waiting on admissions, waiting on discharges on any given day."

In Springfield, only 32% of the surrounding county is vaccinated, and COVID-19 hospitalizations are up more than 210% since June 1. Perhaps most alarming—90% of all COVID samples being sequenced from that county are testing positive for the Delta variant.

McCoy said at his hospital, almost every COVID patient is unvaccinated.

"We've only had two that have come out as in-patients that have been fully vaccinated. The vaccine, from everything we can see, does appear to be effective against the Delta variant," he said.

While there are signs that America is beating back the pandemic with the help of vaccines, there are also indications of a potential new COVID wave.

"The Delta variant is clearly going to be another wave. If you decide not to get vaccinated, this virus will still find you," Osterholm said.

McCoy told Begnaud that while more than 75% of his county's seniors are vaccinated, that number plummets among people aged 21 to 60. He said that percentage is somewhere in the mid-30s, and it's people in that age group that are showing up at his hospital.