FLU cases in Scotland are at their highest level for five years, health officials have said.

Public Health Scotland (PHS) has now raised the incidence of influenza from “high” to “extraordinary” activity level.

Nick Phin, director of public health science at PHS, said: “At this point, we don’t know whether we’ve reached the peak or if it will continue, or we’ll start to see it dip down.”

The latest weekly figures from PHS show there were 1358 influenza cases in Scotland in the week ending December 18.

The hospitalisation rate for influenza has been generally increasing since the middle of the year, PHS added, with this now reaching 7.5 patients per 100,000.

The rate is highest for infants aged under one, at 32.9 per 100,000.

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PHS added that the number of patients in hospital who have tested positive for influenza so far this season is higher than it has been since 2017.

Phin said: “The figures that we are publishing today show that flu detections, positive tests, are at a level probably last seen in 2017-18 season.

“This is the highest they’ve been since that particular time, it’s a fairly sharp increase.

“The figures are the highest in the last five years, the number of notifications we currently usually get precede with an increase in activity in hospitals probably by a week to 10 days, so we expect to see the current activity in hospital to continue at least for the forthcoming week or so.

“There are things that we can do – people should be offered the vaccination. The second thing is we have antivirals and these are available on prescription to certain groups should they develop a flu-like illness. We know if given early these can have an impact to reduce severity of illness some people may get.”

He said the upcoming school Christmas break could slow the spread of the virus, as “children tend to be fairly active spreaders of flu amongst themselves and the community”.

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An estimated 2,475,611 Scots have been vaccinated against flu so far this year, including 1,902,233 adults – of whom 959,719 are aged 65 and over.

Vaccination, together with the use of anti-virals when people have symptoms, can reduce the severity of illness, Phin said.

PHS also found there have been no increase in cases of Group A Strep infections, with the number said to have levelled off.

Cases of this could now decrease next week, PHS added.

While there has been an increase in the number of Covid-19 cases being detected, PHS stressed this will not necessarily lead to a rise in hospitalisations or death – with vaccines and natural immunity meaning experts do not expect the same level of people requiring hospital treatment that there was earlier in the pandemic.