evidence: WHO Health Emergencies Programme [...] It is usual for viruses to change and evolve as they spread between people over time. When these changes become significantly different to a previously detected virus, these new virus types are known as "variants." To identify variants, scientists map the genetic material of viruses (known as sequencing) and then look for differences between them to see if they have changed. Since 2020, SARS-CoV-2, the virus that causes COVID-19, has been spreading and changing globally. These changes have led to the detection of variants in many countries around the world. The more significant of these variants are grouped in three different ways – variants under monitoring, variants of interest and variants of concern.