Speaking exclusively to The Scotsman, Professor Devi Sridhar made the call a week after warning COP26 could lead to a rise in cases and trigger the need for further restrictions.
The chair of global public health at Edinburgh University said this may not amount to a 2020-style lockdown, but instead “protections” should be put in place.
This should happen sooner rather than later, she argued, as experts expect COP26 to cause a spike in cases around the end of November, when the NHS, already struggling to cope, will be facing the beginning of winter.
“I think what people need to realise is that when they need the NHS in December, it may not be there in the way we want it to be if we don't put in protections,” she said.
The climate conference will lead to more mixing, more Covid cases and more pressure on the health service, she said.
“We know there's not much room to manoeuvre right now within the NHS and so when people ask if we’re going to have restrictions, I say we possibly could, depending on how the NHS looks, and right now it doesn’t look great,” she said.
One mistake during the pandemic has been to think of restrictions as “lockdown or nothing”, Prof Sridhar added.
Instead, the government should think about “protections”, including encouraging vaccine take-up, and a wider vaccine passport scheme.
Existing rules require anyone aged 18 and over to provide evidence of their full vaccination or exemption before entering a nightclub, an unseated indoor event with more than 500 people, an unseated outdoor event with more than 4,000 people or any gathering with more than 10,000 attendees.
Prof Sridhar said: “If we look at New York City, France, Italy, Germany ... they're much stricter on indoor venues.
"If you go to a coffee shop in Germany and you sit outside, they don't ask you for any proof of anything. But if you want to go inside, you need to show proof of a negative test in the past 24 hours or double vaccination.
"This is the way they've kept their indoor settings safer. It's not 100 per cent, but it's good enough and it offers the option that if you do want to still go, you can sit outside and stay out of the riskier settings.”
Prof Sridhar expects this idea to be “controversial”, but likens it to laws meaning customers at indoor venues have to go outside if they want to smoke.
“We use public policy to make it safer for the community, while also getting people to choose the option,” she said.
“If they don't want to be vaccinated, that’s fine, but they they need to sit outside.”
Prof Sridhar added: “The thing I think that is tragic now is we're having people die who probably don't need to die. Our case rates are so much higher and our death rates are so much higher than other countries in Europe.
“If there are things we could do to bring that down, why wouldn’t we?"
Scotland’s vaccine passport scheme is already controversial among opposition MSPs, and an extended system would be certain to draw further criticism.
The Liberal Democrats labelled the existing system an “assault on medical privacy”.
Party leader and health spokesperson Alex Cole-Hamilton said: "The SNP's poorly planned and illiberal Covid ID card scheme is unworkable and only gives people a false sense of security.
"If we were to copy the system EU countries adopted, it would be to introduce the option of providing a negative test result or proof of recent infection as an alternative to vaccine certification.
"It's time to ditch this assault on medical privacy and focus on what actually works – vaccines and an effective contact tracing operation."
Scottish Conservative shadow Covid recovery spokesperson Murdo Fraser said: “The SNP’s vaccine passport scheme has already had a devastating effect on venues that currently fall under the scheme, with nightlife businesses reporting a drop in trade of nearly 50 per cent.
“Extending vaccine passports to even more indoor venues in Scotland would be catastrophic for businesses that are only just beginning to recover from the pandemic.
“The Equality and Human Rights Commission has already raised concerns over the SNP’s shambolic vaccine passport scheme. They should be dropping it, not considering an extension of it.”
According to Prof Sridhar, allowing proof of a negative test as well as vaccination would work, but only if testing was very easy and readily available.
The Scottish Government said it had “no current plans” to extend the vaccine passport scheme.
A spokesperson said: “We will, however, keep this under review to ensure our certification scheme remains necessary, proportionate and targeted.”
Prof Sridhar’s suggestion to expand the vaccine certification scheme comes as national clinical director Professor Jason Leitch said GPs have had to make “difficult choices” about which patients to see during the Covid pandemic.
Professor Leitch insisted it would “not be the right thing to do” to force family doctors back to conduct all appointments on a face-to-face basis.
The Scottish Government’s NHS recovery plan seeks to “fully restore face-to-face consultations in GP surgeries and other primary care services as a priority”.
It comes after GPs and other medical professionals moved to telephone and video consultations after coronavirus hit Scotland.
But more than 18 months after the pandemic began, MSPs on Holyrood’s Covid-19 recovery committee questioned Prof Leitch and Scottish Government minister Graeme Dey on Thursday on the level of access to GPs.
Labour MSP Alex Rowley said: “People out there in communities who are feeling ill are finding it difficult to get a face to face appointment.”
He added: “I know from people who have contacted me, struggling to get a GP appointment, struggling to see anybody in the medical centres.
“They eventually present themselves to the hospital and find out that it is cancer and it has moved on stages.”
Prof Leitch stressed GP practices had been “open throughout” the pandemic, but he added: “They have had to make some difficult choices about who to see and who to see on line and who to do with phone calls.”
He also said face-to-face appointments “never went away,” explaining: “Some people get face to face appointments.
“The decision on who is based on safety and the health of those individuals and that has to be clinical decisions made locally.”
But Mr Rowley argued: “There is a responsibility on government when people feel ill and feel they need to have a face-to-face appointment with a medical person. It is the responsibility of government to ensure those people can access face to face appointments.”
The committee debate came as Scotland recorded 20 coronavirus deaths and 2,153 new cases in the 24 hours to Thursday.
It means the death toll under this daily measure – of people who first tested positive for the virus within the previous 28 days – is 9,119.
The daily test positivity rate was 6.3 per cent, down from 8.9 per cent the previous day, figures published by the Scottish Government show.
There were 932 people in hospital on Wednesday with recently confirmed Covid-19, up seven on the day before, with 58 in intensive care, up one.