Scientists scramble to determine if mutant strain of coronavirus will deepen pandemic

The COVID-19 vaccines rolling out across the nation are lifting spirits over the holidays. But there's also budding concern about new strains of the virus that have been discovered in Great Britain, South Africa and possibly in Nigeria. Scientists say they are hopeful, but unsure, that the vaccines will repel the mutants. The variant found in Great Britain may be more contagious than the original virus. And it's unclear if the pathogens will take hold in the U.S., where nearly 19 million people have already been infected. There's lots of uncertainty because things are happening quickly. Resear...