H1N1 (2009) Influenza Update

Current Situation

  • Despite the media reporting – indicative data suggests the peak was probably passed over the Christmas weekend. We will not know this for sure until Thursday 6th January.
  • The number of deaths is small so far, compared to former years, although tragic for families affected. An indication that the H1N1 2009 virus has not mutated and continues to cause a milder illness than seen with previous viruses. Sadly, most deaths would probably not have occurred if influenza vaccination had been sought by those in the at-risk groups – the samples taken across the country show the vaccine to be well matched to the virus.
  • There are a large number of people in the population who were exposed to the virus during the Pandemic (probably only 50% had an influenza-like illness, albeit mild), and will now have immunity, plus 35M who accepted the H1N1 vaccine at the time. Combined this makes a formidable “resistance” population to the spread of the infection.
  • Flu activity this winter is in most respects very similar to that seen in most winters. The exception is that the over 65s have a lower incidence of illness. This seems to be a characteristic of the H1N1 virus, which was a common virus in the 1920s, 30s and 40s and it is presumed that there is a high level of immunity in the over 65 group (this also reflects what happened during the last pandemic).
  • The group that are experiencing serious illness are those younger people with underlying disease. Of the 39 deaths so far reported only 1 had received immunisation, and most had underlying disease. Within the total, 3 cases are Influenza B – which is also in the vaccine.
  • As in most years, children are the major carriers of the virus, but few have serious illness unless very young (<5).
  • Activity levels, although higher than the 2-3 years before the pandemic, are still not at epidemic level – a level well below that of pandemic.
  • Influenza viruses “prefer” cold temperatures and this is likely to be the reason that we have seen a sharp rise in reported infections. With the onset of warmer weather it is thought we will see a decrease in the rate of rise of infections, or even a fall. A further peak is possible if we have another cold snap or, more likely, when the children go back to school, although significant numbers of children were exposed in the pandemic and there may not be enough vulnerable individuals to sustain further extensive transmission.


Despite media hype our advice to clients at this time is no different from other normal winters.

CATCH IT. BIN IT. KILL IT. is a simple way to remember this.

Margaret Murray
Cigna UK Occupational Health Manager 
2nd January 2011

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