ONE of Nicola Sturgeon’s top Covid-19 advisers has indicated that Scotland’s tier system should be permanently binned - as she warned “harsh restrictions” are needed to have any impact on suppressing the virus.

Professor Devi Sridhar, the chairwoman of global public health at Edinburgh University, has praised the First Minister’s announcement that mainland Scotland is set for a three-week lockdown from Boxing Day – but has indicated that the tight measures will continue to be needed in order to tackle the pandemic.

On Saturday, Ms Sturgeon announced all of mainland Scotland will be place in level 4 lockdown restrictions from Boxing Day for a three-week period and prior plans to ease rules for five days over Christmas have been scaled back to just Christmas Day.

The First Minister also announced a travel ban over Christmas, which was originally due to be relaxed to allow festive meet-ups, will be in force between Scotland and the rest of the United Kingdom.

READ MORE: Warning new Covid-19 variant could be 'big trouble' for Scotland

Speaking on Sky News’s Sophy Ridge on Sunday programme, Professor Sridhar warned the new variant of the virus, which can spread 70 per cent more easily than the original strain, means “it’s going to become harder to suppress it with our existing tier system”.

She added: “We just need a broader strategy with what to do with this virus.

“The more that we’ve seen about it, we’ve seen we have to pivot away from a flu model which is accepting this is a seasonal infection which is endemic – towards more of a SARS model where we really try to keep the numbers as low as possible and use testing, vaccines, treatments to keep a handle on it and try to keep our economy and society going.

“I think trying to keep these low-level restrictions for a long period of time is not going to work with this virus – it's too infectious, it looks like it's becoming more infectious.”

Professor Sridhar said politicians were forced into an “impossible situation” over the u-turn over Christmas.

She said: “You’re stuck between what people want to hear, what they want to do, fatigue, as well as what we know scientifically we need to do to suppress this virus.

“Unfortunately with the emergence of this new strain as well as rising prevalence, they were forced into these restrictions.

“As long as this virus is circulating, it is too risky to allow travel across the country as well as indoor mixing.”

The expert said the rest of the UK should follow Scotland’s lead in using a “harsh lockdown” to “really crunch” and eliminate the virus to the lowest level possible.

She added: “If we look at Scotland, Scotland was already running a lower infection rate but to go into quite a harsh lockdown over the holiday period, to extend the school holidays, to really try to get those numbers low, I think, I would hope the rest of the UK would follow that model, which is we have got to really crunch this.

“We have got to eliminate as much as possible to the lowest level of this virus because that is how we will reopen our economy.

“The countries that are keeping a lid on this are doing it by keeping their numbers really low through clear public health guidance and measures.”