Influenza activity in Portugal: 2012/2013 season

Guiomar, Raquel; Conde, Patrícia; Cristóvão, Paula; Nunes, Baltazar; Pechirra, Pedro

http://hdl.handle.net/10400.18/3568

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Abstract(s)

Preliminary data (up to W18/2013) suggests that during the 2012/2013 winter season the influenza activity was moderate (max. 70.2 ILI cases/105 inhabitants on week 10/2013, provisory estimate), with an epidemic period of 8 weeks (W4/2013 to W12/2013). Since week 40/2012, 1261 nasopharyngeal swabs were analysed: 268 (22.0%) were Influenza A positives, from which 233 (19.0%) were A(H1)pdm09. Influenza B was detected in 282 (22.2%) specimens, the majority ascribed to B/Yamagata lineage (21.0%). Influenza A(H3) and B/Victoria viruses were sporadically detected. Although the majority of ILI cases (43.2%) were from adults (15-44 years), the highest proportion (61.8%) of influenza cases was observed in children (5-14 years). Information on influenza vaccination with the 2012/2013 trivalent vaccine was available for 89.5% of cases, from those 9.3% was vaccinated and among these 14.5% were influenza positive. The RSV was detected since week 1/2013, with the highest number of positives in week 11/2013. Most of the RSV was detected in the age group ≥ 65 years. Influenza A viruses were antigenic and genetically similar to the vaccine strains. On the other hand the Influenza B viruses show a greater antigenic and genetic variability. The majority of the strains were antigenically similar to B/Massachusetts/2/2012, which will integrate the vaccine next winter, and genetically belonged to clade 2 (B/Estonia/55669/2011). A total of 248 A(H1)pdm09 and 80 B viruses were tested for antiviral susceptibility (PCR (NA)-H275Y and/or MUNANA phenotypic assays for oseltamivir and zanamivir) none of them showed genetic or phenotypic reduced inhibition by antivirals.