Commentary
Explosion
of H1N1
Cases in South Korea
Recombinomics Commentary
18:47
January 10, 2009
82 viruses were identified as A/H1 type and 13 viruses were identified as A/H3 type
322 influenza viruses were isolated until the 51th week in 2008-2009 season.
296 viruses were identified as A/H1 type and 26 viruses were identified as A/H3 type
815 influenza viruses were isolated until the 52th week in 2008-2009 season.
767 viruses were identified as A/H1 type, 46 viruses were identified as A/H3 type and 2 viruses were identified as B type.
The above comments are from the Korean CDC reports for weeks 50, 51, and 52. The proportion of patients visiting sentinel physicians for influenza like illness rose to 15.39%, which was significantly above the 2.6% baseline. The levels for this season and last season are graphically represented in the week 52 report.
Although the reports do not indicate the frequency of Tamiflu resistance, recent reports from Japan describe influenza forced closing of elementary schools in October and November due to Tamiflu resistant H1N1. A recent WHO report on H274Y frequencies in initial weeks of the influenza season in the northern hemisphere indicated that 13/14 H1N1 in Japan were Tamiflu resistant and all isolates from the school closings were Tamiflu resistant. Three isolates from Sendai, Japan matched each other as well as the dominant sub-clade circulating the United States (HI, TX, PA), and all had H274Y in NA and A193T on HA. In the United States, Tamiflu resistance levels in H1N1 are at 98%, indicating most isolates are from the same sub-clade, as seen in the HA and NA sequences released by the CDC in the United States.
The school closing sin Japan and the explosion of cases in South Korea support an aggressive H1N1 that is resistant to Tamiflu.
More information on resistance and sequences from the isolates in South Korea would be useful.
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