Severe acute respiratory syndrome coronavirus 2 escape mutants and protective immunity from natural infections or immunizations

Although coronaviruses have lower mutation rates than other respiratory RNA viruses, the scale of the pandemic has brought the importance of viral evolution for coronaviruses to centre stage. It has long been known that coronaviruses can evolve through acquisition of mutations and through recombination, but knowledge in the field is far behind that of some other viruses with global reach. This pandemic has seen an unprecedented amount of genomic sequencing, which is starting to open up an entirely new field of research: real-time tracking of viruses on a global scale, and trying to predict what mutations and deletions may be relevant. During the global dissemination and long chains of transmission, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has diversified with accumulation of mutations. Many of these mutations are neutral, in the sense that they do not affect any of the properties of the virus, some reflect the geographical dispersal of the virus (founder effects), and some have raised concern because they may allow the virus to evade immunity generated in response to previous infection or enhance transmissibility through mechanisms that are as yet undefined [[1]]. Increasing population immunity through natural infections and immunizations will increase the selection pressure on the virus and probably increase the evolution of new escape mutants. This brief review examines virus variants and individual mutations of current concern, including evidence for their importance for transmission and pathogenicity.