The new Covid variant does not appear to be more deadly - but urged people to get their booster vaccines.
Professor Calum Semple, who advises the Government as part of the Scientific Advisory Group for Emergencies (SAGE), told BBC Breakfast that the Omicron variant will reach the UK "by hook or by crook".
It has been branded a variant of concern by the World Health Organisation, and is causing alarm among the scientific community.
Prof Semple said he is hopeful Omicron - which was first identified by scientists in South Africa - will not evade vaccines.
He said: "It's very early days, we've only known about this virus for a few weeks.
"The evidence is its not causing more death and that's important.
"The problem this might present is it might evade some of the vaccines but it might not evade the boosters or the two proper doses."
He encouraged people to go and get their coronavirus booster vaccines.
Speaking about the decision to place six countries on the red travel list, Professor Semple added: "If you can slow the virus coming into the country because you're timed for the booster campaign to get ahead of it, and it leaves the scientists to see if there is anything to worry about, which it doesn't seem it.
"The virus will get here by hook or crook, eventually, it will come here as people are asymptomatic, but it doesn't mean we shouldn't try and slow it down."
He said he is an advocate of masks and hand-washing and said: "I feel particularly uncomfortable on public transport.
"I'm pro-mask in the shops and public transport. We still have high levels of coronavirus but the vaccines are working."
Today health officials in Germany and the Czech Republic confirmed cases of the new variant are believed to have been detected.
Kai Klose, social affairs minister in Hesse, home to Frankfurt airport, Germany's biggest hub and one of Europe's busiest airports, tweeted: "Last night several Omicron-typical mutations were found in a traveller returning from South Africa."
