Scotland flu rate higher than average for time of year

Only a fraction of cases are ever detected through laboratory testing, but this data is used to estimate the overall prevalence in the community. 

Current estimates put the incidence rate for influenza at 2.4 per 100,000. 

This is considered 'low', but compares to around one per 100,000 at the same time of year for the three years prior to the pandemic: 2017/18, 2018/19, and 2019/20. 

READ MORE: The strange viral consequences of lockdown 

In each those years, cases went on to peak between late December and early February, with flu rates reaching a high of 26 per 100,000 in 2017/18 - the most recent bad flu season.  

It comes amid warnings that the UK could face a 'twindemic' of Covid and flu this winter, following two winters with virtually no influenza at all as a result of measures such as social distancing and masking introduced to curtail the pandemic. 

Flu rates in Scotland currently are low, but above average and on rise (Source: PHS) (Image: PHS)

The number of laboratory-confirmed cases of flu in the most recent two weeks is nearly on a par with the 2021/22 peak (Source: PHS) (Image: PHS)

The number of laboratory confirmed cases in Scotland during weeks 40 and 41 - at 155 in total - compares to around 20 during weeks 40 and 41 last year. 

Influenza ctivity appears to be highest in Lanarkshire currently, where it increased from low to 'moderate' (5.1-14.7 per 100,000) in the most recent week. 

However, regional estimates can be skewed by comparatively small or large numbers compared to the population size. 

NHS Lanarkshire appears to have the highest flu rates currently (Source: PHS) (Image: PHS)

The report from Public Health Scotland indicates that while case numbers are higher than average for the time of year, the number of people in hospital with flu is lower than in pre-pandemic years. 

PHS notes that the number of influenza-related hospital admissions in Scotland has been increasing since June.

By the start of the 'flu season' in week 40, "there were 54 patients in hospital who tested positive for influenza".

Of these, the majority (49) had Influenza Type A, of an "unknown subtype". This is in line with patterns already seen globally during the winter flu season in the southern hemisphere.  

READ MORE: Australia flu surge could be very bad news for the NHS 

The hospitalisation rate for influenza in Scotland was one per 100,000 in week 40, rising to four per 100,000 for patients aged 75 and older.

PHS added: "The number of hospitalised patients who tested positive for influenza reported so far this season is lower than that for the five previous seasons prior to the Covid-19 pandemic."

The number of people hospitalised with influenza in the 2017/18 season peaked at more than 1000, and at 500 in 2019/20. 

However, the number in hospital currently with flu is around five times higher than it was at the same time last year. 

The number of patients in hospital in Scotland with a positive influenza test is around six times higher than it was a year ago (Source: PHS) (Image: PHS)

Compared to the same weeks in pre-pandemic years, the number of flu patients in hospital remains comparatively low (Source: PHS) (Image: PHS)

By October 16, more than 870,000 eligible adults had been vaccinated against flu. 

This included nearly 60% of over-65s and 83% of elderly residents in care homes, who were prioritised for the inoculation. 

Coverage is lower for other groups, ranging from just under 10% for clinically vulnerable 18-64-year-olds and 16% of social care workers, to 36.5% of healthcare workers. 

The majority (94%) of those receiving a Covid winter booster who are also eligible for a flu vaccine have received both vaccines at the same appointment.

The dominant flu strains circulating globally over the past year are a non-subtyped form of Influenza A (dark green) and Influenza A(H3). This is similar to current patterns in Scotland (Source: PHS/WHO) (Image: PHS/WHO)

Meanwhile, the PHS report notes that in Australia - whose flu season is seen as a potential bellweather for the UK - influenza activity is now low after peaking in June.

Australia experienced a steep, early surge in cases from around April onwards, but the infection to mortality ratio was lower than it had been during the 2017 flu season. 

READ MORE: How will Covid affect the NHS this winter? 

In the year to date, Australia's cumulative notification rate for flu nationally is 875.4 per 100,000 population. 

This exceeds levels seen during most of the pre-Covid years. For example, flu rates ranged between 121.8 to 422.3 per 100,000 in the years from 2011 to 2018, with the exception of 2017 which remains a record-breaking year for flu in Australia with a total notification rate of 1021.4 per 100,000 population.