Over the last few weeks, the United Kingdom and South Africa have faced a rapid increase in COVID-19 cases leading to enhanced epidemiological and virological investigations. Analysis of viral genome sequence data identified a sizeable proportion of cases belonging to new phylogenetic clusters. The new SARS-CoV-2 variants are defined by nonsynonymous, several of which are found in the viral spike protein, and still of uncertain functional significance. While it is known that viruses constantly change through mutation, and seldom does it lead to biological changes, the variants now increasingly observed in the UK and South Africa may be associated with increased infectivity.