Vigilancia de la gripe en España Temporada 2015-2016 (desde la semana 40/2015 hasta la semana 20/2016)

[ES] La actividad gripal en Espana en la temporada 2015-16 fue baja y asociada a una circulacion mayoritaria de virus de la gripe A(H1N1)pdm09, con una creciente contribucion de virus de la gripe B a medida que ha ido avanzando la temporada. La epidemia gripal se inicio de forma tardia, presentando posteriormente una onda epidemica atipica, con una meseta de incidencia de gripe estable durante varias semanas consecutivas y una duracion total en el rango de las 10 temporadas previas. Los menores de 15 anos fueron el grupo de edad mas afectado, con mayores tasas de incidencia acumulada en el grupo de 0-4 anos. Se notificaron 12 brotes confirmados de gripe en siete CCAA. El 92% de los brotes se asocio a virus tipo A (siete A(H1N1)pdm09, 3 ANS y uno A(H3N2)) todos ellos en centros sanitarios, geriatricos o instituciones de larga estancia. De las 2.716 detecciones centinela identificadas a lo largo de la temporada, el 66% fueron virus de la gripe A, 98% de A(H1N1)pdm09, entre los subtipados. A nivel global se puede distinguir una primera onda de circulacion de virus A(H1N1)pdm09 y posteriormente otra con circulacion de virus B. En las redes centinela con picos de intensidad gripal mas tempranos se ha observado una mayor contribucion de virus A(H1N1)pdm09, mientras que en aquellas con periodos epidemicos mas tardios se observo una mayor contribucion de virus B. La caracterizacion genetica de los virus circulantes esta temporada indico que todos aquellos virus A(H1N1) caracterizados eran semejantes a A/SouthAfrica/3626/2013, todos los virus A(H3N2) eran semejantes a A/HongKong/4801/2014 y la practica totalidad (96%) de virus de la gripe B eran semejantes a B/Brisbane/60/2008 (linaje Victoria). Se notificaron 3.101 casos graves hospitalizados confirmados de gripe (CGHCG) en 19 CCAA, de los que 1.071 (35%) fueron admitidos en UCI y 352 (11,4%) fallecieron. La mayor proporcion de casos se concentro en los mayores de 64 anos (40%), seguido del grupo de 45-64 anos (33%). Las mayores tasas de hospitalizacion se observaron en los mayores de 64 anos y en el grupo de 0 a 4 anos. En el 85% de los casos se confirmo el virus de la gripe tipo A, siendo el 98% de los subtipados (H1N1)pdm09. El 75% de los CGHCG presento algun factor de riesgo de complicaciones de gripe. El 64,5% de los pacientes pertenecientes a grupos donde estaba recomendada la vacunacion, no habian recibido la vacuna antigripal de esta temporada. Las defunciones en casos graves hospitalizados confirmados de gripe se concentraron fundamentalmente en los mayores de 64 anos (59%) y el 88% de los casos fatales presento algun factor de riesgo de complicaciones. El 59% de los pacientes recomendados de vacunacion no habian recibido la vacuna antigripal de esta temporada. La letalidad observada en terminos de defunciones entre CGHCG fue inferior a la temporada previa, y similar a las anteriores. El sistema MOMO (Monitorizacion de la mortalidad diaria) estimo un exceso de mortalidad por todas las causas en las semanas 9, 11, 13 y 14/2016 que se concentro en el grupo de 15 a 64 anos. Excesos similares se han informado en varios paises europeos. [EN] Influenza activity in Spain during the 2015-16 season was low and dominated by influenza A(H1N1)pdm09 virus circulation, with an increasing contribution from B virus as the season progressed. Influenza epidemic had a late time presentation, showing an atypical epidemic wave afterwards, with a stable incidence plateau for several consecutive weeks. The total duration was in the range of the previous 10 seasons. Children under 15 years old have been the most affected with higher rates of cumulative incidence in 0-4 age group. Twelve laboratory-confirmed influenza outbreaks were reported in seven autonomous regions (AR), 92% of them associated with type A virus (seven A(H1N1)pdm09, 3 A not subtyped and one A (H3N2), all in health centers, nursing homes or long-stay institutions. Of the 2,716 specimens from sentinel sources tested positive for influenza virus throughout the season, 66% were influenza A virus, with A(H1N1)pdm09 representing 98% of those subtyped. Globally, a first wave associated with A(H1N1)pdm09 can be distinguished, and then another associated with B virus. In those sentinel networks with early intensity peak, a greater contribution of virus A (H1N1) pdm09 has been observed, while those with later epidemic periods where associated with greater contribution of B virus. All A(H1N1)pdm09 virus genetically characterized have been similar to A/ SouthAfrica/3626/2013, all A(H3N2) were similar to A/HongKong/4801/2014 and almost all (96%) of influenza B viruses were similar to B/Brisban /60/2008 (Victoria lineage). A total of 3,101 severe hospitalized laboratory-confirmed influenza cases (SHCIC) were reported in 19 AR, of which 1,071 (35%) were admitted to ICU and 352 (11.4%) died. The highest percentage of SHCIC occurred over 64 years (40%), followed by the 45-64 age group (33%). The highest hospitalization rates were observed over 64 years and in the group of 0-4 years. The 85% of SHCIC were associated with influenza A virus, and the vast majority of the subtyped A viruses (98%) were A(H1N1)pdm09. Seventy-five percent had underlying conditions and 64.5% had not received a seasonal influenza vaccine. Most of the deaths of SHCIC (59%) were in adults over 64 years old. Eighty-eight percent had underlying conditions and 59% of patients with recommended vaccination condition had not received a seasonal influenza vaccine. MOMO system (Monitoring daily mortality) estimated an excess mortality from all causes in weeks 9, 11, 13 and 14/2016 which focused on the group of 15-64 years. Similar excesses have been reported in several European countries