Table 2.

Variants of concern.

Variant name	Lineage	Status
Alpha	B.1.1.7	It first appeared in the United Kingdom in December, and it is estimated to be 50% more contagious. Now it is the dominant variant in the US.
Beta	B.1.351	In December, it appeared in South Africa.Some vaccines' effectiveness is reduced.
Gamma	P.1	In late 2020, it appeared in Brazil.These variants’ mutations are comparable to those found in B.1.351.
Delta	B.1.617.2	It is very prevalent in India,Among all other variants, only this variant carries the L452R spike mutation.