According to WHO there are currently 4 types of COVID -19 strains circulating all around the world since November 2020. It believes that SARS-CoV-2 variant with a mutation of D614G has replaced the original SARS-CoV-2 strains which was first seen in Wuhan. 3rd strains was identified in Denmark & was named “Cluster 5” and only 12 cases was reported of the variant infecting humans till Sept 2020. The 4th strain was reported in UK on dec 14 and named SARS-CoV-2 VOC 202012/01 & has N501Y mutation.