SCOTLAND is likely to experience "quite a surge" in Covid infections over the coming weeks, a health expert has said.

Jillian Evans, head of health intelligence at NHS Grampian, said the outlook was uncertain but that the spread of a number of new variants of concern posed a risk in particular to people who had not been infected or vaccinated in the past six months or more.

She backed extending top-up Covid vaccinations to the entire adult population ahead of winter.

READ MORE: Herd immunity and the threat from New York's 'son of BA.2' variant 

Speaking on the BBC Scotland Lunchtime Live programme, Ms Evans said: "For many of us, we're now seven-eight months away from that [first booster] so is our immunity starting to change?...the likelihood is that if you've had a recent booster or you've recently had Covid then you may be fairly well protected.

"But it's the people who are further away from either natural infection or their last jab who are probably most at risk, not just of catching it but the effects of it."

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HeraldScotland: The percentage of the population with Covid in Scotland has begun increasing, in line with a growing share of infections being caused by 'S-gene negative' strains which include BA.1, BA.4 and BA.5The percentage of the population with Covid in Scotland has begun increasing, in line with a growing share of infections being caused by 'S-gene negative' strains which include BA.1, BA.4 and BA.5

She said she "would prefer" to see boosters offered to all in the coming months, adding: "It makes sense for you to be prepared for what is going to be a difficult autumn period.

"I know it's very much focused on the most at risk people at the moment, but if we're likely to experience wave after wave then I think the main thing we can do is to keep up to date with as many protections through vaccination as we can afford."

The call was echoed by Scottish Government Covid adviser, Professor Devi Sridhar, who wrote that the UK "should be planning to roll out boosters to the entire population this autumn, using an age and risk factor priority scheme". 

The Spring boosters have been rationed to people over 75, those in care homes and those with weakened immune systems. 

Prof Sridhar, who is chair of global public health at Edinburgh University, added that supplies of Covid antivirals should also be "put in place in pharmacies and GPs, working towards a 'test to treat' scheme where soon after testing positive, those who are in vulnerable and elderly groups, for whom vaccines might be less effective, can get access to effective treatment early on". 

Currently, anyone eligible for Covid antivirals in the community has to call an NHS helpline with supplies home-delivered if patients meet the criteria.

The latest weekly data from the Office for National Statistics' household surveillance estimates that the prevalence of the virus in Scotland had risen from one in 50 to one in 40 people infected by the week ending June 2 - the highest rate among the UK nations.

Infections had previously been falling steadily since March.

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It comes amid signs that new sublineages of Omicron - BA.4 and BA.5 - are on the rise in the UK.

They have already been implicated in recent Covid waves in South Africa and Portugal, while a third Omicron subvariant - BA.2.12.1 - has rapidly gained ground in North America.

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Ms Evans said: "There are at least three variants of concern that we're looking at that have driven other waves of infection in other countries.

"South Africa is just coming out of a wave of infections, but closer to home Portugal is still experiencing a wave of infection...It becomes difficult for us to learn solely from other countries because are all experiencing waves and different types of waves at different times, so you can't just look abroad and think 'that's what will happen here'."

She added that the increasing dominance of new variants of concern mean that a new wave is likely, cautioning: "How big that wave is is very, very uncertain, but it's likely I think that we will experience quite a surge of infections over the coming weeks."

READ MORE: Two new Covid strains designated variants of concern amid warnings of summer surge 

Ms Evans stressed that there was no cause for "panic", but that clinicians feared the potential impact of a resurgence in other viruses later in the year while Covid rates remain high.

She said: "The worry will be as we get out of the summer season and into autumn, the possibility to of influenza returning at the same time as Covid is one that everyone is nervous about...another good reason for you to keep wearing the masks in indoor spaces when you've got lots of people around you so that it doesn't just protect you from Covid but from all those other viruses as well."

Official data suggests that around one in three people are still using facemasks in Scotland, after the legal requirement lifted in April.

HeraldScotland: Reported facemask use in Scotland (Source: Modelling the Epidemic)Reported facemask use in Scotland (Source: Modelling the Epidemic)

It comes after Health Secretary Humza Yousaf said that Scotland "will probably continue to see some level of rise in cases" over the coming weeks, based on ONS data and wastewater sampling.

Like the original BA.1 strain of Omicron, the BA.4 and BA.5 sublineages have genetic changes which mean a marker known as the S-gene is no longer detectable.

This distinguishes them from the BA.2 strain responsible for the UK-wide Covid wave in March and April, which is S-gene positive and remains dominant.

According to the ONS, between May 2 and May 29 this year 90.7% of all sequenced Covid-19 infections were caused by Omicron BA.2 infections, with 3.8% due to BA.5 infections, 3.4% due to BA.4 infections, and 0.5% by Omicron BA.1 or one of its sublineages, such as BA1.1.

HeraldScotland: Covid rates are tracked by sampling wastewater across Scotland for virus tracesCovid rates are tracked by sampling wastewater across Scotland for virus traces

The latest Modelling the Epidemic report for Scotland states that the prevalence of the virus in wastewater sampling nationally "has remained between 50 and 100 million gene copies per person per day since the start of May, but there is variability in the data and the trend is uncertain".

The number of people in hospital with Covid has climbed slightly from a recent low of 590 on May 29 to 637 by June 5 - substantially higher than the 112 Covid patients in hospital a year prior.

HeraldScotland: Hospital Covid cases remain much higher compared to summer 2021Hospital Covid cases remain much higher compared to summer 2021

Although many are not sick as a result of the infection, it can slow recovery from other ailments, increases the risk of hospital spread, and puts pressure on beds as Covid wards have to be created and closed to non-Covid cases in order to isolate patients with the virus regardless of their symptoms.