As viruses spread between people they can change, getting better at infecting them or spreading faster. Scientists track these changes in real time by mapping the genetic material of viruses (known as sequencing) and comparing them to previous versions. The more significant changes are known as variants. Viruses that have changed in a way that affects how they spread or make people sick are called variants of concern, variants of interest or variants under monitoring.
Since the start of the pandemic in 2020, many different COVID-19 variants have been detected. The most important ones have been named Alpha, Beta, Gamma, Delta and now Omicron.
Omicron has a higher number of mutations in the spike protein than the other four, and it has demonstrated significantly altered transmissibility and immune escape. This is why it has been classified as a variant of concern by the World Health Organization and national public health agencies.
Vaccines are designed to protect against these shifting variants but they can also be affected by the emergence of new ones. This can weaken the efficacy of vaccines and lead to reduced herd immunity.
During infection, the virus that causes COVID-19 copies itself and then passes on this copy to other people. Occasionally, the virus can change slightly and these changes are picked up in lab tests. If these changes are significant, they can cause people to get seriously ill and can stop antibodies that fight the virus from working effectively. This is why it’s so important that people continue to practice good hygiene, avoid contact with others and vaccinate themselves against COVID-19.
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