Total confirmed cases reported on Saturday barely exceeded 100,000, a sharp downturn from around 800,850 five weeks ago on January 16, according to Johns Hopkins University data.
In New York, the number of cases went down by more than 50 per cent over the last two weeks.
"I think what's influencing the decline, of course, is that Omicron is starting to run out of people to infect," said Thomas Russo, professor and infectious disease chief at the University of Buffalo's Jacobs School of Medicine and Biomedical Sciences.
COVID-19 hospitalisations are down from a national seven-day average of 146,534 on Jan. 20 to 80,185 the week ending in February 13, according to the Centers for Disease Control and Prevention COVID data tracker.
Public health experts say they are feeling hopeful more declines are ahead and the country is shifting from being in a pandemic to an 'endemic' that is more consistent and predictable.
However, many expressed concern that vaccine uptick in the US has still been below expectations, concerns that are exacerbated by the lifting of COVID-19 restrictions.
William Schaffner of Vanderbilt University's School of Medicine said on Sunday that the downturn in case numbers and hospitalisations was encouraging. He agreed that it likely has a lot to do with herd immunity.
"There are two sides to Omicron's coin," he said. "The bad thing is that it can spread to a lot of people and make them mildly ill. The good thing is it can spread to a lot of people and make them mildly ill, because in doing so, it has created a lot of natural immunity."
However, DR Schaffner said it was too early to "raise the banner of mission accomplished. As a public health expert, he said he would be more comfortable if the decline sustained itself for another month or two.
Officials in many states are cutting back on restrictions, saying they are moving away from treating the coronavirus pandemic as a public health crisis and instead shifting to policy focused on prevention.
16°C