Epidemiology of the 2009 influenza pandemic in Spain. The Spanish Influenza Surveillance System.

In accordance with European Centre for Disease Prevention and Control recommendations, the Spanish Influenza Surveillance System (SISS) maintained its activity during the summer of 2009, and since July 2009 the pandemic virus activity was monitored by the SISS. In this paper, we describe the epidemiological and virological characteristics of the 2009 pandemic in the Spain through the SISS. Spain experienced a transmission of the new A(H1N1)pdm09 influenza virus during the summer of 2009, which gradually increased, resulting in the pandemic wave in early autumn of that year. The reproductive number R0, estimated during the growth phase of the pandemic wave (1.32; 95% confidence interval [95%CI], 1.29-1.36), showed a transmissibility comparable to preceding pandemics. There was an almost complete replacement of the previous seasonal A(H1N1) influenza virus by the pandemic virus A(H1N1)pdm09. The pandemic virus produced a greater burden of illness than seasonal influenza in children younger than 15 years old, while the incidence in those older than 64 years was lower compared with previous inter-pandemic seasons. Nevertheless, in Spain the 2009 pandemic was characterized as mild, considering the duration of the pandemic period and the influenza detection rate, both in the range of those observed in previous inter-pandemic seasons. Also, the case fatality ratio (CFR) was estimated at 0.58 deaths/1,000 confirmed ILI cases (95%CI, 0.52-0.64), in the range of the two previous pandemics of 1957 and 1968, with the highest CFR observed in the older than 64 years age group. In the 2009 pandemic there was a higher percentage of pandemic confirmed deaths in the younger ages, compared to seasonal influenza, since only 28% of the reported deaths occurred in persons aged 64 years and older.

[Surveillance of influenza pandemic (H1N1)2009 in Spain]. / Vigilancia de la pandemia de gripe (H1N1) 2009 en España.

BACKGROUND: During the summer of 2009, Spain experienced the circulation of the novel influenza (H1N1)2009 virus, beyond the usual period of influenza activity, increasingly evolving up to the presentation in the early autumn of the first wave of the pandemic virus. The objectives of this study are to describe the evolution of the pandemic wave in our country and to assess their impact on morbidity and mortality of the Spanish population. METHOD: From the information obtained from the Spanish Influenza Surveillance System and the Coordinating Centre for Health Alerts and Emergencies within Spanish Ministry of Health and Social Policy have been estimated a number of epidemiological and virological indicators that were used to assess the level of activity and intensity of the pandemic wave, as well as its severity RESULTS: The beginning of the pandemic wave in Spain started in early autumn 2009 reaching the maximum weekly incidence rate of 372.15 cases/100,000 inhabitants. The highest incidence was registered in under 15 years old. Viral detection rate registered during the pandemic period remained at the range of previously recorded (46.4%). We estimated an overall mortality rate of 0.43 deaths per 1,000 pandemic cases. The 64% of deaths from pandemic influenza occurred in young adults and the highest mortality rates were registered in the 45-64 years age group with 9.35 deaths/1,000,000 inhabitants. Mortality associated with seasonal influenza in the period 2001-2008 was highest in those over 64 years (95% of all deaths). CONCLUSIONS: The influenza (H1N1)2009 pandemic wave in Spain showed an early presentation and a medium level of influenza intensity compared to the previous thirteen seasonal influenza waves. Considering lethality or mortality rates, this first pandemic wave was also characterized by a mild severity, although a high percentage of deaths confirmed by the new virus were observed in population under 65 years.

[Excess mortality in Spain during transmission of pandemic influenza in 2009]. / Excesos de mortalidad en España durante la transmisión de gripe pandémica en el año 2009.

BACKGROUND: The Spanish daily mortality monitoring system and the program «European monitoring of excess mortality for public health action¼ found two excesses of mortality in Spain in November and December 2009. METHODS: We analyzed the evolution of mortality in Spain during those months using time-series analysis methods based on historical mortality series and compared it in the time with influenza transmission. RESULTS: Observed mortality for the total population was higher than expected in two periods: weeks 46-47/2009 with 5.75% excess and weeks 51-52/2009 with 7.35% excess. Observed mortality higher than expected, was also observed in children 5-14 years old during weeks 46-48/2009 with 41 deaths vs 21 expected. Exces mortality in November occurred before or was concomitant with highest influenza incidence rates. Excess mortality in December occurred five weeks after the influenza incidence peak and along with dramatic drop in temperatures. RSV and traffic accidents were ruled out as factor associated to these excesses. CONCLUSIONS: While temperatures could explain most of the excess mortality observed in December, no single factor could be associated with observed excess mortality in November.

Epidemiology of tuberculosis in Spain. Results obtained by the National Epidemiological Surveillance Network in 2015. / Epidemiología de la tuberculosis en España. Resultados obtenidos por la Red Nacional de Vigilancia Epidemiológica en el año 2015.

The epidemiological surveillance data for tuberculosis in Spain in 2015 is analysed in this report. This information was gathered through cases reported to the Red Nacional de Vigilancia Epidemiológica [National Epidemiological Surveillance Network]. In addition, the update of the treatment of the cases reported in 2014 is included. The incidence rate of tuberculosis in 2015 was 10.59 cases per 100,000 inhabitants, 10% less than in 2014. This decrease was mainly due to the sustained decreased trend of pulmonary tuberculosis rates, from other locations and in adults, while for cases of tuberculous meningitis and in children the decrease is less marked, with a tendency to stabilization. The percentage of cases born in other countries remains stable (approximately 30% of the total). Information on HIV status is available in 63% of cases, of which 7% were HIV-positive. Regarding the treatment results, 77% of the new lung cases confirmed by culture reported in 2014 had a satisfactory result, 6% died, and 11% did not have this information.

[cycEVA study: case control study measuring influenza vaccine effectiveness in Spain, 2008-2013]. / Estudio cycEVA: casos y controles para la estimación de la efectividad de la vacuna antigripal en España, 2008-2013.

BACKGROUND: In Spain, influenza vaccine effectiveness (EV) is estimated since 2008-09 season through the cycEVA case-control study, the Spanish component of the European I-MOVE (Monitoring Influenza Vaccine Effectiveness in the EU/EEA) network. We aimed at describing cycEVA performance in its five consolidated editions 2008/09 -; 2012/13. METHODS: During the study period the following indicators were analysed: 1) the participation of sentinel general practitioners and pediatricians (MP), 2) the population studied and the study period, 3) the data quality and 4) the dissemination of the cycEVA results. Trend analysis of the indicators was done using the Cochran-Armitage test to compute the Annual Percentage Change (PCA). RESULTS: The number of participating MP increased from 164 in 2008-09 to 246 in the following editions. The percentage of MP recruiting at least one patient increased significantly annually (PCA = 15.33%). The percentage of recruited patients included into the analysis increased (PCA=5.91%) from 77% in 2008-09 to more than 95% in the following editions. The percentage of cycEVA patients contributing to the I-MOVE study ranged between 23% and 30% in the pilot and 2011-12 editions respectively.. Final results were disseminated in quartile 2 peer-reviewed journals and 2010-11 and 2011-12 preliminary EV estimates were published in quartile 1 journals. cycEVA publications received 97 citations. CONCLUSION: cycEVA study achieved more quality information, timely EV estimates and a higher impact of the results.

[Premature mortality excess related to influenza in Spain during an interpandemic period]. / Exceso de mortalidad precoz relacionado con la gripe en España durante un período interpandémico.

BACKGROUND: The indicator of Potential Years of Life Lost (PYLL) has been frequently used to analysis of premature mortality and recently has been used to estimate the impact of the last influenza A(H1N1)pdm09 pandemic. The aim of this study was to estimate the excess deaths from pneumonia and influenza (P&I) in Spain and the PYLL during the period 1980-2008, measuring the mortality attributable to influenza regarding the type/subtype of influenza dominant in each season. METHODS: Monthly excess deaths were calculated with cyclical regression models. The PYLL calculation was performed as the product of the number of excess deaths and the difference between life expectancy at birth and years lived for each age group. The analysis of the variation between P&I excess deaths and PYLL, depending on the predominant influenza virus type/subtype was carried out with a Poisson regression analysis. RESULTS: In seasons dominated by influenza virus A(H3) the average P&I excess deaths was estimated at 1,348, and for PYLL in 5.297, while in seasons dominated by A(H1) or B the average P&I excess deaths was 648, and for PYLL 2.885. The adjusted rate ratios of excess (2.11, CI-95%=2.05-2.16) and PYLL (1.86, CI-95%=1.83-1.88) indicate that the relative frequencies for both indicators are significantly larger in seasons dominated by influenza virus A(H3). CONCLUSIONS: Excess deaths and PYLL doubled when comparing seasons predominantly subtype A(H3) and other influenza viruses.

[Transmissibility and severity of the pandemic influenza A (H1N1) 2009 virus in Spain]. / Transmisibilidad y gravedad de la pandemia de gripe A(H1N1)2009 en España.

OBJECTIVES: To estimate the value of the basic reproduction number for the pandemic wave of influenza A (H1N1) 2009 in Spain and to assess its impact on morbidity and mortality in the Spanish population compared with those in the previous influenza season. METHODS: Data on the incidence of influenza and viral detections were obtained from the Spanish Influenza Surveillance System. Deaths from pandemic influenza were obtained from the Coordinating Center for Health Alerts and Emergencies of the Spanish Ministry of Health and Social Policy, and deaths from seasonal influenza during the period 2003-2008 were obtained from the National Statistics Institute. The reproduction number was estimated by two methods: firstly, by using the growth rate of the cumulative incidence of influenza during the exponential growth phase of the pandemic wave, and secondly (maximum likelihood estimation), through analysis the dates of onset of symptoms observed in pairs of cases based on generation time distribution. We calculated the fatality rate and mortality from influenza by comparing potential years of life lost in the pandemic season with those in previous interpandemic seasons. RESULTS: The start of the pandemic wave occurred in Spain earlier in week 40/2009 (from 4 to 10 October), with an absolute predominance of the new strain in the pattern of circulating viruses. The value of R(0) in the growth phase of the wave was 1.29 (95% CI: 1.25-1.33), estimated with the first method, and was 1.01 (95% CI: 0.99-1.03) with the second method. During the pandemic season, there were 318 deaths from pandemic influenza, affecting younger age groups than in previous interpandemic seasons. Consequently, the number of potential years of life lost in the pandemic season (11,612) was estimated at six times the adjusted annual average of the interpandemic influenza seasons for comparison (1,802). CONCLUSIONS: The estimates of R(0) for the growth phase of the pandemic wave were in the lower range of estimates of this parameter in previous pandemics. Mortality indicators calculated in the pandemic period showed an increase in deaths compared with previous interpandemic seasons, which was most pronounced in young patients.