World Health Organization (WHO) is monitoringOne of these variants, the delta variant — also known as the B.1.617.2 lineage — was first identified in India in December 2020 and quickly became the most common variant in the country.It has demonstrated 40–60% increased transmission, in comparison with the previously dominant alpha variant, and is currently the dominant SARS-CoV-2 variant in the United Kingdom.Meanwhile, researchers recently identified another variant — the delta plus variant, also known as B.1.617.2.1 or AY.1.