The Omicron variant of the SARS-CoV-2 virus spread rapidly, even in those who had been vaccinated against it. This study examined the different DNA sequence of this viral variant to determine mutations in the virus from patient blood samples from the ISARIC4C study and the effect these mutations have on the ability for the vaccination to prevent infection or illness. Understanding these alterations can help with future vaccine strategies and prevent more rapidly spreading SARS-CoV-2 variants in the future.