Viruses like SARS-CoV-2 continuously evolve as changes in the genetic code (caused by genetic mutations or viral recombination) occur during replication of the genome. Most changes have little to no impact on the viral properties. However, some changes may affect how easily the virus spreads, the associated disease severity, or the performance of vaccines, therapeutics or diagnostic tools etc. During late 2020, the emergence of SARS-CoV-2 variants that posed an increased risk to global public health prompted the WHO to characterise specific Variants of Interest (VOIs) and Variants of Concern (VOCs). Details on how these variants are designated etc can be found here https://www.who.int/activities/tracking-SARS-CoV-2-variants. To date (Sept. 2022) cases of all five VOCs (B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), B.1.617.2 (Delta) and B.1.1.529 (Omicron)) have been detected in Ireland. Several sublineages of Delta and Omicron variants have also been identified in Ireland.

The interim case definition for variants of concern (VOC) for public health response and an overview of the procedures for the laboratory detection of mutations or variants of concern are available here.