U.S. Coronavirus cases are falling but experts say it's not from the COVID vaccine, yet

Coronavirus cases are falling in the US but experts say it's not from the COVID vaccine, yet Health experts say it's still too early to see any impacts from the COVID-19 vaccine on US case numbers. Adrianna Rodriguez USA TODAY

New coronavirus cases are on the decline in the United States following staggering post-holiday peaks last month, but experts say it's too early for new COVID-19 vaccines to be having an impact. 

The positive trend also is not assured to continue, as new and more transmissible variants threaten to reverse it, according to Centers for Disease Control and Prevention Director Dr. Rochelle Walensky. 

"Although we have seen declines in cases and admissions and a recent slowing of deaths, cases remain extraordinarily high, still twice as high as the peak number of cases over the summer," she said this week. 

The decline in cases is likely due to a natural depression after record travel followed by indoor holiday gatherings triggered a surge in infections, said Dr. Sarita Shah, associate professor at Emory University’s Rollins School of Public Health. ...

According to the Transportation Security Administration, the agency screened 1.9 million travelers the day before Christmas Eve setting a pandemic record.

“We’ve seen these rises and falls in the COVID case counts now a few times and they seem to really track along holidays or people’s movements,” Shah said.

COVID-19 symptoms take between two to 14 days to appear after exposure, and cases peaked exactly two weeks after the Christmas holidays, noted Brittany Baker, undergraduate program coordinator and clinical assistant professor at North Carolina Central University. ...