U.S. is in a 'race against time' with new coronavirus variants, scientists warn

The United States is in a race against time to vaccinate as many people as possible before other potentially more worrisome variants of the coronavirus emerge, according to experts.

Vaccination efforts in the U.S. have been hamstrung by delivery issues, insufficient supply and hesitancy to get the shots. But to avert another surge of infections, hospitalizations and deaths, scientists say it may be necessary to rethink how the vaccines are rolled out to ramp up the number of shots administered and to protect against new strains of the virus.