Many COVID-19 cases are caused by variants of the virus, but not all variants cause serious illness or death. Scientists track these mutations because they may affect how the virus spreads or what happens to people who get it. There are three classes of variants: a variant of concern (VOC), a variant of interest (VOI), and a variant under monitoring (VUM).
The fast-spreading Brazil strain, B.1.1.7 (Alpha), has been linked to more severe disease in some people and more deaths. Its changes could help it evade antibodies (made by the immune system after a previous infection or vaccine) that fight coronavirus infections, but lab tests show the Pfizer-BioNTech COVID-19 vaccine works against this variant.
Mutations in the Delta and Omicron variants, found in India and other countries, have made them up to 50% more transmissible. They also appear to have changed the way the virus infects cells and escapes the body’s immune response, making them more deadly.
The Beta and Gamma variants haven’t been spreading as quickly as Alpha, Delta, or Omicron, but their mutations could still make them a public health concern. They have been linked to more severe disease in some people, and they may not be as easily detected by the diagnostic test used for the COVID-19 pandemic. More research is needed to find out if these variants are more likely to cause infection and whether the vaccines that are currently in use will protect against them.