Covid-19 variants pose 'real threat' to vaccine progress, CDC warns March 01, 2021 at 06:53PMhttps://https://ift.tt/3bU4jHZ A top health expert says highly contagious variants of the virus pose a "real threat" to the US.

A top health expert says highly contagious variants of the virus pose a "real threat" to the US.

from BBC News - World https://ift.tt/2Pl7vox