As the new Covid-19 Omicron variant spurs global travel bans, experts say concerns over its impact should prompt millions of unvaccinated Americans to get their shots -- and for those who are eligible, to get their boosters. "I would hope that within the next week or two weeks, so many of those people will take advantage of the vaccine," Dr. William Schaffner, a professor at Vanderbilt University Medical Center, told CNN's Alisyn Camerota Friday. "That will help us in the immediate term. And I would anticipate that, as bad as Omicron might be, our vaccine still will be partially effective."...