Influenza Virus Activity During Pandemic And Seasonal Influenza In Central Greece

In central Greece, during the influenza seasons from 2009-2012, type A influenza A (H1N1) viruses were the dominant subtype to circulate in the population. This viral subtype was detected in 100% of the positive samples assayed, during the 2009-10 and 2010-11 seasons, respectively. This finding coincides with the emergence of pandemic influenza A (H1N1) viruses, globally. The A (H1N1) viruses detected were identified as antigenically similar to the vaccine A (H1N1) pdm 09 viral strains of the respective periods. Overall, with the exemption of the 2011-12 season, where only influenza A (H3N2) and influenza B viruses were detected, in 61% and 39% of the samples assayed by real-time RT-PCR, respectively, A (H1N1) pdm 09 viral strains were isolated from 94% of the positive by real-time RT-PCR samples. These findings support the importance of continuous influenza laboratory surveillance and influenza vaccine formulation according to the antigenic profile of circulating viral strains.