RATES of norovirus have rebounded sharply in Scotland after virtually disappearing during the height of the pandemic.

The number of confirmed laboratory cases by mid-April was around 30 per cent higher than normal for the time of year, and had more than doubled in a single week.

Public Health Scotland cautioned that the laboratory-confirmed cases "represent just a small proportion of the true incidence in the community", as most people make a full recovery without being hospitalised.

Young children and elderly people are at higher risk.

The Herald: (Source: Public Health Scotland)(Source: Public Health Scotland)

Norovirus, also known as the 'winter vomiting bug', is highly contagious and causes severe bouts of vomiting and diarrhoea that tend to last around two days.

Billions of microscopic particles can then be spread by an infected person onto surfaces, doorknobs, utensils and onto food during preparation.

It can also be carried by oysters harvested from contaminated water.

Ingesting only a tiny number of these particles is enough to cause infection, making its very difficult to contain outbreaks in households or hospitals.

In March, four wards with a total of 88 beds between them were closed to new admissions at Dr Gray's Hospital in Elgin in a bid to prevent a norovirus outbreak spreading to new patients.

Raigmore Hospital in Inverness was also forced to close two wards to visitors and new admissions last week as a result of patients infected with norovirus.

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The rise in cases comes as hospital capacity is already stretched by high levels of Covid positive patients, who also also have to be isolated in wards which are then closed to non-Covid admissions.

In the week ending April 17, there were nearly 60 laboratory-confirmed cases of norovirus in Scotland, up from around 24 the week prior and fewer than five a week in January.

The pre-pandemic average for mid-April is around 45cases per week.

In total, there have been 245 laboratory-confirmed cases of norovirus in Scotland so far this year, compared to an average of 524 for the same period pre-pandemic.

However, it compares to just 15 in 2021, when the country was in lockdown as a result of the Alpha variant, and almost none from March 2020 onwards as Covid restrictions closed hospitality venues and indoor household mixing was severely curtailed.

The Herald: (Source: Public Health Scotland)(Source: Public Health Scotland)

It comes as the latest Covid figures show a continued decline in virus rates and hospital admissions for patients with the infection.

As of April 21, there were 1,702 people in hospital with Covid - down from a peak of 2,406 on April 2.

Meanwhile, surveillance carried out by the Office for National Statistics shows a decline in infection rates for the fourth week in a row in Scotland.

In the week ending April 16, one in 19 people in Scotland were estimated to have Covid. That compares to a peak of one in 11 in March.

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Professor Adam Kucharski, an expert in infectious disease at the London School of Hygiene and Tropical Medicine, said the fact that infections had peaked and gone into decline "without new control measures of substantial behaviour change" suggested that herd immunity had been reached, but cautioned that this did not mean infections "will continue to decline indefinitely".

The Herald: ONS surveillance shows a steady decline in the prevalence of Covid since mid-March (Source: Office for National Statistics)ONS surveillance shows a steady decline in the prevalence of Covid since mid-March (Source: Office for National Statistics)

Waning immunity and new variants could propel cases upwards again, he said.

PHS figures also show that fewer than 15% of five to 11-year-olds in Scotland have been vaccinated against Covid since the rollout began in mid-March.

Low uptakes have been seen across the UK.

Kit Yates, a professor of mathematical biology at the University of Bath, said: "Even if it weren't for the hugely mixed messaging on the vaccine for five-11-year-olds, part of the reason for the low uptake is undoubtedly because so many kids have has Covid within the last 12 weeks and so are ineligible."