Here we report the occurrence of an amino acid substitution, aspartic acid to glycine in position 222 (D222G) in the HA1 subunit of the viral haemagglutinin, in clinical specimens from 11 out of 61 cases analysed in Norway with severe outcome. Such mutants were not observed in any of 205 mild cases investigated (Table), thus the frequency of this mutation was significantly higher in severe (including fatal) cases (p<0.001, Fisher’s exact test, two-sided) than in mild cases.
The above comments from a recent report on position 225 (222 in H1 numbering) changes in clinical samples from Norway, flatly refute WHO comments indicating the changes were not significant or not even worth mentioning when found in a death cluster involving transmitting H1N1 at Duke Medical Center.