Two-shots of a Covid vaccine may not be enough against the Omicron variant, and a third dose or a booster shot is necessary to prevent the super mutant variant, according to a UK study. The study, released by the UK Health Security Agency (UKHSA), showed that a full two-dose vaccination course was less effective against symptomatic disease with Omicron than with the original strain of Covid-19 or the Delta variant. On the other hand, a moderate to high vaccine effectiveness of 75 per cent is seen in the early period after a booster dose.

"Early estimates of vaccine effectiveness (VE) against symptomatic infection find a significantly lower VE for Omicron infection compared to Delta infection. Nevertheless, a moderate to high vaccine effectiveness of 70 to 75 per cent is seen in the early period after a booster dose," the agency said in a statement. The study comes as another 448 cases of Omicron were confirmed in the UK, taking the number reported so far to 1,265. The total number of Covid cases recorded on Friday was 58,194 -- the highest figure since January 9, the BBC reported. The report analysed data from 581 Omicron cases and thousands of Delta cases to calculate how effective the vaccines were against the new variant.