October 23, 2008 Since 1 September 2008, National Microbiology Laboratory (NML) has antigenically characterized three influenza viruses: one influenza A/Brisbane/59/2007(H1N1)-like and two influenza B/Florida/4/2006 viruses, which are the influenza A(H1N1) and influenza B components recommended for the 2008-09 influenza vaccine.
The testing results showed that the influenza A(H1N1) isolate was sensitive to amantadine, however, it was resistant to oseltamivir due to the H274Y mutation.
The above data from the most recent (week 41) report on seasonal flu in Canada indicates that the first confirmed influenza A cases this season was H1N1 and was Tamiflu resistant. Data had been trickling in for influenza in the northern hemisphere this flu season. Several countries, including the US and Canada had high frequencies of H274Y in H1N1 isolates, but the above report is on the first Canadian isolate in the 2008/2009 season.
In the southern hemisphere, several countries (South Africa, New Zealand, New Caledonia) reported frequencies of 100%, raising concerns that H274Y was becoming fixed in human H1N1.
The early data from Canada supports concerns that the H274Y levels in H1N1 in the northern hemisphere will be close to 100% this season.