Epidemiology of pandemic influenza A/H1N1 virus during 2009-2010 in Taiwan.
Outbreak of swine-origin influenza A/H1N1 virus (pdmH1N1) occurred in 2009. Taiwanese authorities implemented nationwide vaccinations with pdmH1N1-specific inactivated vaccine as of November 2009. This study evaluates prevalence, HA phylogenetic relationship, and transmission dynamic of influenza A and B viruses in Taiwan in 2009-2010. Respiratory tract specimens were analyzed for influenza A and B viruses. The pdmH1N1 peaked in November 2009, was predominant from August 2009 to January 2010, then sharply dropped in February 2010. Significant prevalence peaks of influenza B in April-June of 2010 and H3N2 virus in July and August were observed. Highest percentage of pdmH1N1- and H3N2-positive cases appeared among 11-15-year-olds; influenza B-positive cases were dominant among those 6-10 years old. Maximum likelihood phylogenetic trees showed 11 unique clusters of pdmH1N1, seasonal H3N2 influenza A and B viruses, as well as transmission clusters and mixed infections of influenza strains in Taiwan. The 2009 pdmH1N1 virus was predominant in Taiwan from August 2009 to January 2010; seasonal H3N2 influenza A and B viruses exhibited small prevalence peaks after nationwide vaccinations. Phylogenetic evidence indicated transmission clusters and multiple independent clades of co-circulating influenza A and B strains in Taiwan.
['Lan|Yu-Ching|YC|', 'Su|Mei-Chi|MC|', 'Chen|Chao-Hsien|CH|', 'Huang|Su-Hua|SH|', 'Chen|Wan-Li|WL|', 'Tien|Ni|N|', 'Lin|Cheng-Wen|CW|']
D000293:Adolescent D000328:Adult D017677:Age Distribution D000368:Aged D000369:Aged, 80 and over D002648:Child D002675:Child, Preschool D005260:Female D006801:Humans D007223:Infant D053118:Influenza A Virus, H1N1 Subtype D053122:Influenza A Virus, H3N2 Subtype D009980:Influenza A virus D009981:Influenza B virus D007251:Influenza, Human D008297:Male D008875:Middle Aged D008969:Molecular Sequence Data D058873:Pandemics D010802:Phylogeny D012621:Seasons D013624:Taiwan D055815:Young Adult
Pandemic influenza Mixed infection HA subtyping Phylogenetic analysis Surveillance