December 21, 2010
As of Monday, there were 24 children under five in critical care with confirmed or suspected flu, another 12 aged five to 15, and 243 in the 16 to 64 age group. There were also 23 people aged over 65 in critical care.
The above comments describe the 302 ICU cases in the United Kingdom, which represents a dramatic jump from the 100 cases described last week. The age distribution indicates the vast majority of cases are H1N1, consistent with media reports describing over 40 H1N1 fatalities, which are also up sharply from the 10 deaths cited last week.
This spike in severe and fatal cases has raised concerns that the H1N1 circulating in the UK is more virulent, leading to death clusters, as described for Bury in the Greater Manchester area.
Such changes can be linked to small genetic changes, such as D225G which was linked to severe and fatal H1N1 cases last season. However, D225G positive H1N1 was relatively rare in 2009 and concentrated in the Ukraine and Russia. The UK and much of western Europe had a frequency of cases with D225E, which is a change that was not associated with an increase in severe or fatal cases.
In 2009 Mill Hill characterized a Ukraine isolate, A/Lviv/N6/2009, as a low reactor, raising concerns that H1N1 with a higher frequency of D225G would be more widespread this season. Such an increase could have profound effects on health care delivery, because such cases occupy ICU beds for an extended time period and frequently require ECMO machines, which are in limited quantities. Use of such machines stretch required transport of at least one patient out of the UK for treatment. Media reports this year have already cited shortages and delays in treatment for some patients. These shortages could become life threatening if the number of ICU cases continues to increase at the pace set in the past several days.
The HPA released four sets of H1N1 sequences yesterday, but none were from collections in December or from hard hit areas like the Greater Manchester region.