All variants are different. The Omicron variant has a large number of mutations which may mean the virus acts differently from other variants that are circulating.
As of 1 December 2021, there is limited information about Omicron. Studies are ongoing to determine if there is a change in how easily the virus spreads or the severity of disease it causes, and if there are any impacts on protective measures.
It will likely take time before there will be clear evidence to determine if there is any change in the transmission of Omicron compared to other variants, how the variant responds to existing therapeutics, or whether infection or re-infection with Omicron causes more or less severe disease.
WHO is working with technical partners to understand the potential impact of Omicron on vaccine effectiveness. Currently, the Delta variant is dominant worldwide and COVID-19 vaccines are highly effective at protecting you from serious illness and death, including from infection with Delta. Researchers will assess the performance of current vaccines against Omicron and will communicate these findings as soon as they become available.