The COVID-19 Delta variant: What is it and why should we worry?

In December 2020, the B.1.617.2 variant, also known as the COVID-19 Delta variant, was first documented in India (1). Originally referred to as the “India variant,” it was given the name Delta after the World Health Organization (WHO) announced a new labelling system for variants of concern on May 31, 2021 (2,3). This system was …