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Influenza A (H1N1) update
20/08/2009
The latest figures about the incidence of influenza A (H1N1) in Scotland have been published today.
Today's findings are:
- A rate of GP consultations for flu-like illnesses - not necessarily H1N1 - across Scotland of 37.9 per 100,000. This is a slight decrease from last week's figure of 44.4.
- The number of community samples that tested positive for H1N1 has slightly increased from last week's figure of 9.5 per cent to 10.9 per cent.
- These rates suggest that around 1060 people have consulted their GP with H1N1 flu in Scotland over the week-long reporting period. However, taking account of the number of people having H1N1 but not consulting their GP, HPS estimate that around 3,030 people have contracted H1N1 in the past week.
- There have been 114 people with influenza A (H1N1) hospitalised since the start of the outbreak. Twenty people have required hospital admission in the the last week and, as of today, there are nine people in hospital in Scotland.
- There have been five deaths linked to influenza A (H1N1) since the start of the outbreak.
Health Secretary Nicola Sturgeon said:
"Today's figures show a slight decrease in the number of people consulting their GP with flu-like symptoms, and another slight decrease in the number of overall estimated cases. The proportion of samples testing positive for H1N1 has increased slightly.
"Fifty-eight practices are providing surveillance information. Over the coming weeks we will continue to increase the number of spotter practices, which will give us an even clearer picture of how the virus is behaving in Scotland.
"NHS 24 and our GPs are responding very well to the pandemic, as is our Scottish flu response service. The latest NHS 24 figures show that the number of flu related daily calls has fallen significantly to around 960, compared to 1,170 last week.
"Simple hygiene measures like frequent handwashing and using tissues can do a huge amount to help prevent flu spreading.
"In the vast majority of cases, most people have fairly mild symptoms and make a full recovery within a week. But it's important that anyone who is at greater risk gets the help they need as quickly as possible.
"Anyone who is concerned about flu-like symptoms should continue to contact their GP for advice, or NHS 24 on 08454 24 24 24."
Calculations
The following method can be used to calculate the approximate number of new cases of H1N1 per week suggested by the GP consultation figures:
Average rate of consultation per day (e.g. Scotland = 37.9) multiplied by population/100,000 (e.g. Scotland = 51.68) = Total daily GP consultations for all flu-like illness (e.g. Scotland = 1958.67).
Multiply this figure by five (GP practice working days) for total weekly number of GP consultations for all flu-like illness (e.g. Scotland = 9,793.36).
The estimated number of actual cases of influenza A (H1N1) is derived from the percentage suggested by laboratory testing of samples (e.g. Scotland = 10.9 per cent).
Therefore: 10.9 per cent of 9793.36 (total consultations for flu-like illness) = 1,067 new cases. It should be emphasised that this is an approximate figure as indicated by random sampling and based on people consulting a GP. Not all people with H1N1 will consult their GP and estimates of the percentage who will consult range from 20 per cent to 50 per cent. With the mid range estimate of 35 per cent we estimate that the total number of people in Scotland who have contracted H1N1 over the last week is 3,039.
Rates of GP consultation for flu-like illness per 100,000 population in Scottish NHS Boards*:
Ayrshire and Arran - 25
Borders - 26
Dumfries and Galloway - 17
Fife - 20
Forth Valley - 30
Grampian - 51
Greater Glasgow and Clyde -37
Highland - 41
Lanarkshire - 19
Lothian - 38
Orkney- 17
Shetland - 21
Tayside - 96
Western Isles - 3
Scotland - 38
* These figures are based on relatively small sample sizes, particularly in smaller boards, so should be interpreted with caution.
Population figures per board area, mid-year 2008 estimates (GROS).
NHS Board areas Population size
Ayrshire & Arran 367,510
Borders 112,430
Dumfries & Galloway 148,580
Fife 361,815
Forth Valley 290,047
Grampian 539,630
Greater Glasgow & Clyde 1,194,675
Highland 309,900
Lanarkshire 561,174
Lothian 817,727
Orkney 19,890
Shetland 21,980
Tayside 396,942
Western Isles 26,200
Scotland 5,168,500