Thursday, January 13, 2011

UK: HPA Influenza Report – Week 2

 

 

# 5229

 

 

While some of the media reports of the past week or so would have the casual observer believing that the UK’s flu outbreak continues to escalate, the numbers reported in the latest weekly report suggest that the situation may be stabilizing.

 

These latest numbers, however, could have been influenced by reporting gaps over the recent holidays, and should be interpreted with caution.

 

And there may also be yet another peak in influenza activity later in the year, particularly if the H3N2 virus should pick up steam.

 

The following chart suggests the number of consults for ILIs (influenza-like-illnesses) may have peaked at roughly half the level of the disastrous 1999-2000 flu season  – although once again, this dip could be an artifact of reduced reporting over the holidays.

 

image

It will take another couple of weeks before we can know if these trends are real and sustainable.

 

 

And as always, numbers like the 112 deaths should be taken with a large grain of salt, as not every flu-related death is attributed to the virus. 

 

Some excerpts from this week’s report follow:

 

 

 

HPA National Influenza Report

A full report will be published weekly.  For further information in the surveillance schemes mentioned in this report, please see the Sources of UK Flu Data page.

 

Figures (including all those found in this report) displaying data from these schemes are available to download as a pdf file:

 

HPA Weekly National Influenza Graphs (PDF, 685 KB)

 

PDF versions of previous reports are available on the archive page.

This week's report is available as a pdf:

HPA Weekly National Influenza Report - week 2 (2011) (PDF, 344 KB)

Report published 13 January 2011

Summary

GP and school closures over the Christmas/New Year period will have affected surveillance indicators so all data should be interpreted with caution.  Indeed, several influenza indicators have apparently plateaued.  GP consultation rates remain above baseline levels in all four countries. Influenza A H1N1 (2009) and B are the predominant circulating viruses with few, sporadic A (H3N2) viruses detected.  The H1N1 (2009) virus strain is virologically and epidemiologically similar to that seen during the pandemic.  The virus strains circulating are overall well matched to the current influenza vaccine.

  • In week 1 (ending 9 January), the weekly influenza/influenza-like illness (ILI) consultation rates increased in England (108.4 per 100,000), Scotland (55.8 per 100,000), Wales (92.8 per 100,000) and Northern Ireland (274.4 per 100,000).
  • The weekly national proportions of NHS Direct calls for cold/flu and fever have decreased in week 1.
  • Eleven acute respiratory disease outbreaks were reported in UK in week 1, three in care homes, two in hospitals, five in prisons and one in a primary school.  This brings the total reported this season so far to 146. 
  • Seventy-six of 156 (48.7%) specimens from patients with ILI presenting to sentinel GPs in England in week 1, were reported as positive for influenza.  The proportion of specimens reported to DataMart (England) as positive for influenza decreased to 27.8% (1,104 of 3,968).  The proportion of samples positive for RSV decreased slightly and was low for rhinovirus, parainfluenza, adenovirus and HMPV. 
  • Currently the main circulating influenza strains are influenza A (H1N1) and influenza B.
  • From week 36, 112 deaths associated with influenza infection have been reported. 
  • By week 1, the proportion of people in England aged over 65 years who had received the 2010/11 influenza vaccine was 70.8%. For those in a risk group aged under 65 it was 46.3%.
  • In Europe, several countries are continuing to report increasing influenza activity, primarily associated with influenza A H1N1 (2009).  In the USA influenza activity has decreased slightly but continued to increased in Canada.  In North America influenza A (H3N2) and B viruses have been predominant.