COVID passports in Europe spurred people back to hospitality and leisure venues because customers perceived them as safer, a virus expert has said.

Dr Christine Tait-Burkard, a specialist in coronaviruses at Edinburgh's Roslin Institute, told the BBC Sunday Show that passports had been a "good motivator" for vaccine uptake in Scotland among younger age groups when they were applied to nightclubs and other large events in October.

However, Dr Tait-Burkard said the potential expansion of the scheme was about making venues safer overall, as well as increasing vaccination rates.

The Scottish Government is set to outline its plans on Tuesday.

READ MORE: Risks and rewards if Scotland emulates Europe's passport schemes

If implemented, the passports would come into effect from December 6 with venues such as bars, restaurants, cinemas and theatres expected to be among those covered.

As well as proof of vaccination, ministers are considering whether customers should also be able to show evidence of a recent negative test either as an alternative to being double-jagged - or in addition to it.

Business leaders have warned that the scheme would trigger a flurry of cancellations and cause logistical problems for the hospitality sector during the busy Christmas party season.

HeraldScotland: Infections in Scotland are showing signs of decline after a recent surge following schools returning from the October breakInfections in Scotland are showing signs of decline after a recent surge following schools returning from the October break

However Dr Tait-Burkard said the opposite had occurred in countries such as France and Italy, where diners have had to show proof of vaccination, a negative test or recovery from Covid since the summer to enter restaurants.

She said: "What we see from Europe is that they had a very similar reaction to the hospitality sector here, which is opposing it because it could damage trade.

"Especially in urban high vaccinated areas, hospitality businesses [in Europe] have said it actually helped in bringing back people because they believe it's a safe environment.

"That is probably something that we have to look at as well: if people think a place to go is safe because other people are vaccinated, so they transmit less, [and] they themselves may be tested or vaccinated, [then] it is a safer space to go to and an easier decision to go."

HeraldScotland: Source: Public Health EnglandSource: Public Health England

Professor Rowland Kao, chair of veterinary epidemiology and data science, at Edinburgh University said passports would "contribute positively" to curbing infections over winter if applied to a wider range of venues, and compared the measure to speed limits when driving.

Prof Kao said: "There's no evidence that they are the panacea - the question is whether or not they can contribute, so speaking epidemiologically, if what you are doing is reducing the amount of contact of unvaccinated people with others in high risk situations, they will contribute positively.

"Civil liberties are not an absolute: we allow all sorts of restrictions on our behaviour if they have the ability to harm others. We have restrictions on speed, we have restrictions on things like seatbelts, so it's not an either/or.

"We need to do a balance between what the restrictions are doing to individuals and what the application of the measures do in terms of preventing harm to others, and we know that vaccines work."

READ MORE: Evidence for vaccine passports published by Scottish Government 

However, Professor Stephen Reicher, an expert in behavioural psychology at St Andrews University, cautioned that the initiative could entrench resistance among vaccine sceptics and said he would prefer to see more done to improve ventilation in public spaces with support to help more people to work-from-home or self-isolate where necessary.

He added: "The key question isn't whether we want to increase vaccination - it's how do we increase vaccination. The impact of vaccine passports is complicated and different on different sections of the population.

"For those who just haven't got round to it, what you might call the vaccine indifferent - they've got nothing against vaccines but they just haven't done it - then it's true that passports give them a reason to get vaccinated. You saw it in Austria, you saw it in France, when you introduce these things you have an immediate surge.

"But the problem is that for people who are sceptical, for people who think vaccines are about controlling you, then actually they become more negative and so you create a larger pool of people who become defiant and resistant and what's more, you give traction to those arguments of political bodies who are saying vaccines are about controlling you.

"So vaccine passports in many ways are a double-edged sword. I think there are better ways to get the vaccine indifferent vaccinated: things like making it easier, making sure vaccines go to people rather than people having to go and get vaccinated."

Prof Reicher said there was "absolutely no evidence" that vaccine passports increased the rate of take up in Scotland.

He said: "The [vaccination] curves are exactly the same as in England where they didn't have passports."

HeraldScotland: Graphs by @TravellingTabbyGraphs by @TravellingTabby

Currently, 72% of people in Scotland have had two vaccine doses compared to 71% in Wales, 68% in England, and 66% in Northern Ireland.

Among the 18 to 29 age group, 72% in Wales and 69% in Scotland are fully vaccinated, compared to 68% in Northern Ireland and 66% in England.

Wales is the only other part of the UK currently using vaccine passports, which were expanded last week to cover cinemas, theatres, and concert halls as well as nightclubs and other large events.

Unlike Scotland, however, the Welsh scheme allows customers to show proof of a negative test for entry as an alternative to being fully vaccinated.

Scotland, which currently has the highest booster uptake in the UK at 25%, also has the lowest Covid rate in the at 387.6 cases per 100,000 compared to 403.2 in England, 529.7 in Wales, and 571.4 in Northern Ireland.