(Reuters) -The U.S. national public health agency said on Tuesday that BA.2 sub-variant of Omicron was estimated to account for more than half the coronavirus variants in the country. A resurgence of COVID-19 cases in parts of Asia and Europe has raised concerns that another wave could follow in the United States, but the country’s health experts believe it is unlikely. Evercore ISI analyst Michael Newshel said the 7-day rolling average for COVID cases bottomed a week ago at just under 29,000 and has stayed at about the same level. “There could be a modest increase in cases in the short term a…