However, Dr. Nancy Cox, director of the Influenza Division at the US Centers for Disease Control and Prevention (CDC), said global H1N1 data so far do not show a clear association between the mutation and severe illness.
The above comments are by an agency in denial. The association between D225G and D225N with severe and fatal H1N1 infections is overwhelming. The recent report from Norway indicated that 9/27 (33%) of fatal cases in Norway had D225G or D225N. However, in Ukraine 30/37 (81%) of autopsy lung samples have D225G and/or D225N (11 have both). Similarly, D225G was in 40% of the fatal lung samples from 1918/1919. The data from Ukraine and 1918 are from direct sequencing.
The CDC has tried to limit the number of positives by excluding samples that are positive in culture but negative in the original sample. However, there is little evidence to support CDC’s position that the negative data is true, while the positive data is false. Direct sequencing lacks sensitivity, and both D225G and D225N are frequently detected as mixtures, either with wild type or each other. The failure to find such mixtures is not unexpected, especially if one polymorphism (D225G) is at low levels, as would be expected in mild cases. The low level of D225G would provide a mechanism for transmission, instead of the WHO position that D225G is not transmitted and spontaneously appears again and again.
Much more via CDC In Denial On H1N1 D225G/N Significance.