The flu rate in Scotland has more than doubled over the past week.
Statistics from Health Protection Scotland showed 107 Scots in every 100,000 of the population were diagnosed with the virus in the week ending 7 January.
That marked a sharp increase from the 46 people per 100,000 with the flu in the last week of 2017.
The flu status has been raised from “normal” seasonal activity to “moderate”.
The figures also showed that a further 30 patients needed intensive care.
The HPS statistics revealed that mortality rates related to the virus were still “low”, with eight out of the total of 53 intensive care cases having died
Last week’s number of cases is four times higher than the figure recorded in the first week of last year when 24.6 people in every 100,000 had the virus.
Health Secretary Shona Robison said the NHS was coming under “significant pressure” as a result of higher flu levels.
She thanked staff for doing “a remarkable job”, adding: “These statistics confirm what we’ve been hearing up and down the country that the complexity of treating flu, including appropriate diagnosis and segregation to avoid cross-contamination, is putting our health system under significant pressure.
“Emergency departments saw the highest level of attendances over the festive period in a number of years. During the two-week festive period attendances were up 10 per cent compared to the previous year, with a 20 per cent rise in the week leading up to Christmas.
“Despite these challenges, over 82 per cent of patients were still seen within the four-hour target in Scotland’s core A&Es throughout December, compared to 77.3 per cent in England.
“Staff up and down the country are doing a remarkable job and I am continuing to visit hospitals around the country to thank them personally for their hard work and dedication during this busy time.”
Deputy Chief Medical Officer Dr Gregor Smith encouraged people eligible for free vaccination, including the elderly, young children, mothers-to-be and health workers, to make sure they were protected from the disease.
He said: “While we’ve still got a couple of months of winter left, this week’s statistics provide further evidence that the vaccine is a good match against the current most common strains. I would encourage anyone in an eligible group to get vaccinated. It is the best defence against flu.
“The best way to stop the spread of flu is to follow simple hygiene practices. Wash your hands often with warm water and soap, use tissues to trap germs when you cough or sneeze, and bin those tissues as quickly as possible.
“It is so important that people are aware of the steps they can take to avoid being struck down by the virus, and know that it’s not too late to be vaccinated.”