LONDON — A newly-discovered mutation of the delta variant is being investigated in the U.K. amid worries that it could make the virus even more transmissible and undermine Covid-19 vaccines further.

As the delta variant of coronavirus continues to spread across the world, a relative of the deadly strain is sparking concerns among health officials in South Korea, one of several countries to record ...

The new Omicron variant of coronavirus, with its many mutations and seemingly quick spread in South Africa, is worrying scientists and government officials. But doctors want to remind Americans that ...

Delta deadliest among COVID-19 variants, say CCMB scientists. Five different SARS-CoV-2 variants were chosen and scientists ...