British Health Secretary Sajid Javid said on Monday that the Omicron variant of COVID-19 is spreading at a "phenomenal rate," so people should get an additional dose of the vaccine because double-jabbed people are also vulnerable.

"What we now know about Omicron is that ... it's spreading at a phenomenal rate, something that we've never seen before, it's doubling every two to three days in infections," Javid told Sky News. "That means we're facing a tidal wave of infection, we're once again in a race between the vaccine and the virus."

He said there had been no deaths yet confirmed in England and just 10 people were hospitalized in England with the variant. Omicron was probably behind around 40 percent of infections in London, he added.

UK reported its first Omicron cases on November 27.

Some scientists around the world have said that Omicron variant is believed to be less severe than Delta variant. 

(With input from Reuters)