In COVID-19, variants are emerging coronaviruses with differences in their genetic sequence or observable characteristics (phenotype). Their relative transmissibility, severity, immune escape and impact on diagnostics and vaccines are changing in real time. These changes are driving the need for new working definitions that include and exclude variants on a regular basis.
Variant naming and tracking are important parts of the global surveillance system. The Global Initiative on Sharing Avian Influenza Virus Genome Sequences (GISAID), the Phylogenetic Assignment of Named Global Outbreak Variants (PANGO) and the software-based Lineage Nomenclature Tool (Nextstrain) all make these genomic sequences available for public use.
Using the genetic information from these sequences and observing the phenotype of a virus, scientists can gather data on how the virus spreads, how severe disease is in humans and whether certain groups are at greater risk for developing a serious infection (such as people age 65 or older, pregnant women or those with certain health conditions). These tests help scientists determine how well the current vaccines and other mitigations work.
Recommendations are based on the latest science.