New virus variants of Sars-CoV-2 are constantly emerging. This is a natural process that occurs as the virus spreads: Every time the DNA of the virus is replicated, there is a chance of errors, so called mutations. On average, around two mutations of the SARS-CoV-2 virus occur every month.
These mutations permit scientists to distinguish between different genetic lineages or variants of the virus. While most mutations are of no use to the virus, in rare cases they may prove advantageous. For instance, some variants may be more transmissible. However, the manner in which they infect human cells remains the same.
At the moment, the most widespread virus variants are the lines B.1.617.2 (Delta) and BA.1/BA.2 (Omicron), which were first discovered in India and South Africa. Both of these lines have different changes in their genetic material, some of which occur in the spike protein region.
Initial studies show that the from Moderna and Pfizer/Biontech offer also with the Omicron variant a high level of protection against a severe course of the disease. In contrast, they provide only limited protection against infection with Omicron (asymptomatic or mild course). The efficacy of the different vaccines towards the new variants is currently being further investigated.