Estimating the influenza vaccine effectiveness in Spain using the test-negative case control study design

Tesis doctoral inédita, leída en Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Medicina Preventiva y Salud Pública y Microbiología. Fecha de lectura: 25/04/2014

[Incidence and risk factors for acute gastroenteritis among pilgrims following the French way to Santiago de Compostela (Spain) in summer 2008].

OBJECTIVES: To determine the incidence of acute gastroenteritis in pilgrims on St. James' Way, as well as associated risk factors and microbiological characteristics. METHODS: Two studies were designed simultaneously: a cross-sectional study through self-completed questionnaires among pilgrims reaching Santiago, and a case-control study of pilgrims traveling along the Way. Multivariate analysis was performed using logistic regression. RESULTS: In the cross-sectional study, the incidence rate was 23.5 episodes of acute gastroenteritis/10³ pilgrims-day (95% CI: 18.9-2.4/10³. In the case-control study, the major risk factors were age <20 years (OR=4.72; 95% CI: 2.16-10.28), traveling in groups (three or more) (OR=1.49; 95% CI: 0.98-2.28), and drinking unbottled water (OR=2.09; 95% CI: 0.91-4.82). The most frequent etiologic agent was norovirus (56%). CONCLUSIONS: Age less than 20 years, traveling in groups and drinking unbottled water were important risk factors for acute gastroenteritis

Estimates of Pandemic Influenza Vaccine Effectiveness in Europe, 2009–2010: Results of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) Multicentre Case-Control Study

Results from a European multicentre case-control study reported by Marta Valenciano and colleagues suggest good protection by the pandemic monovalent H1N1 vaccine against pH1N1 and no effect of the 2009–2010 seasonal influenza vaccine on H1N1

Effect of high-valency pneumococcal conjugate vaccines on invasive pneumococcal disease in children in SpIDnet countries: an observational multicentre study

Background The Streptococcus pneumoniae Invasive Disease network (SpIDnet) actively monitors populations in nine sites in seven European countries for invasive pneumococcal disease. Five sites use 13-valent pneumococcal conjugate vaccine (PCV13) alone and four use the ten-valent PCV (PCV10) and PCV13. Vaccination uptake is greater than 90% in six sites and 67–78% in three sites. We measured the effects of introducing high-valency PCVs on the incidence of invasive pneumococcal disease in children younger than 5 years. Methods We compared the incidence of invasive pneumococcal disease in each of the 4 years after the introduction of PCV13 alone or PCV10 and PCV13 with the average incidence during the preceding period of heptavalent PCV (PCV7) use, overall and by serotype category. We calculated incidence rate ratios (IRRs) and 95% CIs for each year and pooled the values for all sites in a random effects meta-analysis. Findings 4 years after the introduction of PCV13 alone or PCV10 and PCV13, the pooled IRR was 0·53 (95% CI 0·43–0·65) for invasive pneumococcal disease in children younger than 5 years caused by any serotype, 0·16 (0·07–0·40) for disease caused by PCV7 serotypes, 0·17 (0·07–0·42) for disease caused by 1, 5, and 7F serotypes, and 0·41 (0·25–0·69) for that caused by 3, 6A and 19A serotypes. We saw a similar pattern when we restricted the analysis to sites where only PCV13 was used. The pooled IRR for invasive pneumococcal disease caused by non-PCV13 serotypes was 1·62 (1·09–2·42). Interpretation The incidence of invasive pneumococcal disease caused by all serotypes decreased due to a decline in the incidence of vaccine serotypes. By contrast, that of invasive pneumococcal disease caused by non-PCV13 serotypes increased, which suggests serotype replacement. Long-term surveillance will be crucial to monitor the further effects of PCV10 and PCV13 vaccination programmes in young children

I-MOVE Multi-Centre Case Control Study 2010-11: Overall and Stratified Estimates of Influenza Vaccine Effectiveness in Europe

BACKGROUND: In the third season of I-MOVE (Influenza Monitoring Vaccine Effectiveness in Europe), we undertook a multicentre case-control study based on sentinel practitioner surveillance networks in eight European Union (EU) member states to estimate 2010/11 influenza vaccine effectiveness (VE) against medically-attended influenza-like illness (ILI) laboratory-confirmed as influenza. METHODS: Using systematic sampling, practitioners swabbed ILI/ARI patients within seven days of symptom onset. We compared influenza-positive to influenza laboratory-negative patients among those meeting the EU ILI case definition. A valid vaccination corresponded to > 14 days between receiving a dose of vaccine and symptom onset. We used multiple imputation with chained equations to estimate missing values. Using logistic regression with study as fixed effect we calculated influenza VE adjusting for potential confounders. We estimated influenza VE overall, by influenza type, age group and among the target group for vaccination. RESULTS: We included 2019 cases and 2391 controls in the analysis. Adjusted VE was 52% (95% CI 30-67) overall (N = 4410), 55% (95% CI 29-72) against A(H1N1) and 50% (95% CI 14-71) against influenza B. Adjusted VE against all influenza subtypes was 66% (95% CI 15-86), 41% (95% CI -3-66) and 60% (95% CI 17-81) among those aged 0-14, 15-59 and ≥60 respectively. Among target groups for vaccination (N = 1004), VE was 56% (95% CI 34-71) overall, 59% (95% CI 32-75) against A(H1N1) and 63% (95% CI 31-81) against influenza B. CONCLUSIONS: Results suggest moderate protection from 2010-11 trivalent influenza vaccines against medically-attended ILI laboratory-confirmed as influenza across Europe. Adjusted and stratified influenza VE estimates are possible with the large sample size of this multi-centre case-control. I-MOVE shows how a network can provide precise summary VE measures across Europe

Using surveillance data to estimate pandemic vaccine effectiveness against laboratory confirmed influenza A(H1N1)2009 infection : two case-control studies, Spain, season 2009-2010

Background: Physicians of the Spanish Influenza Sentinel Surveillance System report and systematically swab patients attended to their practices for influenza-like illness (ILI). Within the surveillance system, some Spanish regions also participated in an observational study aiming at estimating influenza vaccine effectiveness (cycEVA study). During the season 2009-2010, we estimated pandemic influenza vaccine effectiveness using both the influenza surveillance data and the cycEVA study. Methods: We conducted two case-control studies using the test-negative design, between weeks 48/2009 and 8/2010 of the pandemic season. The surveillance-based study included all swabbed patients in the sentinel surveillance system. The cycEVA study included swabbed patients from seven Spanish regions. Cases were laboratory-confirmed pandemic influenza A(H1N1)2009. Controls were ILI patients testing negative for any type of influenza. Variables collected in both studies included demographic data, vaccination status, laboratory results, chronic conditions, and pregnancy. Additionally, cycEVA questionnaire collected data on previous influenza vaccination, smoking, functional status, hospitalisations, visits to the general practitioners, and obesity. We used logistic regression to calculate adjusted odds ratios (OR), computing pandemic influenza vaccine effectiveness as (1-OR *100. Results: We included 331 cases and 995 controls in the surveillance-based study and 85 cases and 351 controls in the cycEVA study. We detected nine (2.7%) and two (2.4%) vaccine failures in the surveillance-based and cycEVA studies, respectively. Adjusting for variables collected in surveillance database and swabbing month, pandemic influenza vaccine effectiveness was 62% (95% confidence interval (CI): -5; 87). The cycEVA vaccine effectiveness was 64% (95%CI: -225; 96) when adjusting for common variables with the surveillance system and 75% (95%CI: -293; 98) adjusting for all variables collected. Conclusion: Point estimates of the pandemic influenza vaccine effectiveness suggested a protective effect of the pandemic vaccine against laboratory-confirmed influenza A(H1N1)2009 in the season 2009-2010. Both studies were limited by the low vaccine coverage and the late start of the vaccination campaign. Routine influenza surveillance provides reliable estimates and could be used for influenza vaccine effectiveness studies in future seasons taken into account the surveillance system limitations

Incidence and risk factors for acute gastroenteritis among pilgrims following the French way to Santiago de Compostela (Spain) in summer 2008.

[ES] Conocer la incidencia de gastroenteritis aguda en los peregrinos del Camino de Santiago, los factores de riesgo asociados y su caracterización microbiológica. Se diseñaron dos estudios simultáneos, uno transversal mediante encuestas autocumplimentadas de peregrinos llegados a Santiago y otro de casos y controles a los peregrinos en el camino. Se hizo un análisis multivariado mediante regresión logística. En el estudio transversal la densidad de incidencia fue de 23,5 episodios de gastroenteritis aguda por 1.000 peregrinos-día (intervalo de confianza del 95% [IC95%]: 18,9–29,4/103). En el estudio de casos y controles los factores de mayor riesgo fueron la edad <20 años (odds ratio [OR]=4,72; IC95%: 2,16–10,28), viajar en grupo (tres personas o más) (OR=1,49; IC95%: 0,98–2,28) y consumir agua no embotellada (OR=2,09; IC95%: 0,91–4,82). Norovirus fue el microorganismo aislado con más frecuencia (56%). Ser peregrino menor de 20 años, realizar el camino en grupo y consumir agua no embotellada se asocian con un mayor riesgo de presentar gastroenteritis aguda. [EN] To determine the incidence of acute gastroenteritis in pilgrims on St. James' Way, as well as associated risk factors and microbiological characteristics. Two studies were designed simultaneously: a cross-sectional study through self-completed questionnaires among pilgrims reaching Santiago, and a case-control study of pilgrims traveling along the Way. Multivariate analysis was performed using logistic regression. In the cross-sectional study, the incidence rate was 23.5 episodes of acute gastroenteritis/10³ pilgrims-day (95% CI: 18.9-2.4/10³. In the case-control study, the major risk factors were age <20 years (OR=4.72; 95% CI: 2.16-10.28), traveling in groups (three or more) (OR=1.49; 95% CI: 0.98-2.28), and drinking unbottled water (OR=2.09; 95% CI: 0.91-4.82). The most frequent etiologic agent was norovirus (56%). Age less than 20 years, traveling in groups and drinking unbottled water were important risk factors for acute gastroenteritis.Para desarrollar el trabajo de campo, el Centro Nacional de Epidemiología (Instituto de Salud Carlos III) financió el desplazamiento y las dietas de los miembros del PEAC, la Consellería de Sanidade de Galicia aportó el material técnico necesario y cedió un vehículo para los desplazamientos a lo largo del Camino, y S.A. de Xestion do Xacobeo facilitó el alojamiento de los investigadores de campo.S

Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against Invasive Pneumococcal Disease incidence in European adults aged 65 years and above : results of SpIDnet/I-MOVE+ multicentre study (2012-2016)

Background and Aims: We measured the effectiveness of 23-valent pneumococcal polysaccharidic vaccine(PPV23) against invasive pneumococcal disease (IPD) in 65+ year-olds, pooling surveillance data from seven European sites. PPV23 vaccination is recommended in all sites (8-69% uptake) and PCV13 in high risk groups in two sites (<5%uptake). Methods: We compared the vaccination status of IPD cases caused byPPV23 serotypes (cases) to that of nonPPV23 IPD (controls) notified between2012 and 2016. We defined PPV23 vaccination as at least one dose. PPV23 pooled effectiveness was calculated as (1 –odds ratio of vaccination)*100, adjusted for site, age, sex, underlying conditions and year. We stratified PPV23effectiveness by time since last dose of vaccine: <2, 2-4, 5-9 and 10+years. Results: We included 2011 cases and 878 controls. Compared to controls,cases were younger (p=0.001), less likely to have an underlying condition(p=0.025), more likely to be admitted for intensive care (p=0.038) and to have pneumonia (p=0.005). PPV23 effectiveness was 24% (95%CI: 4; 41) against PPV23-serotypes.By serotype, PPV23 effectiveness ranged between -2% (95%CI: -48; 30) against serotype 3 (n=687) and 55% (95%CI: 15; 76) against serotype 9N IPD (n=540). By years since vaccination, PPV23 effectiveness was 43% (95%CI: 3-66) and 15%(95%CI: -25; 43) for <2 years and 10+ years, respectively. Conclusion: Our findings suggest a low PPV23 effectiveness against IPD caused by PPV23serotypes in the elderly, varying by serotype, and higher in the first two years after vaccination. Despite low effectiveness, PPV23 in the elderly may prevent at least 25% of cases among vaccinated

Exposure Patterns Driving Ebola Transmission in West Africa:A Retrospective Observational Study

BackgroundThe ongoing West African Ebola epidemic began in December 2013 in Guinea, probably from a single zoonotic introduction. As a result of ineffective initial control efforts, an Ebola outbreak of unprecedented scale emerged. As of 4 May 2015, it had resulted in more than 19,000 probable and confirmed Ebola cases, mainly in Guinea (3,529), Liberia (5,343), and Sierra Leone (10,746). Here, we present analyses of data collected during the outbreak identifying drivers of transmission and highlighting areas where control could be improved.Methods and findingsOver 19,000 confirmed and probable Ebola cases were reported in West Africa by 4 May 2015. Individuals with confirmed or probable Ebola ("cases") were asked if they had exposure to other potential Ebola cases ("potential source contacts") in a funeral or non-funeral context prior to becoming ill. We performed retrospective analyses of a case line-list, collated from national databases of case investigation forms that have been reported to WHO. These analyses were initially performed to assist WHO's response during the epidemic, and have been updated for publication. We analysed data from 3,529 cases in Guinea, 5,343 in Liberia, and 10,746 in Sierra Leone; exposures were reported by 33% of cases. The proportion of cases reporting a funeral exposure decreased over time. We found a positive correlation (r = 0.35, p ConclusionsAchieving elimination of Ebola is challenging, partly because of super-spreading. Safe funeral practices and fast hospitalisation contributed to the containment of this Ebola epidemic. Continued real-time data capture, reporting, and analysis are vital to track transmission patterns, inform resource deployment, and thus hasten and maintain elimination of the virus from the human population

Estudio cycEVA: casos y controles para la estimación de la efectividad de la vacuna antigripal en España, 2008-2013

Fundamentos: Desde 2008-09 la efectividad de la vacuna (EV) antigripal en España se estima con el estudio de casos y controles para la evaluación de la EV antigripal (cycEVA), componente español de la red europea (Influenza-Monitoring Vaccine Effectiveness (I-MOVE). El objetivo es describir la evolución del estudio cycEVA durante las cinco temporadas del período 2008/09– 2012/13. Métodos: Se analizaron los siguientes indicadores: 1) participación de los médicos/pediatras centinela (MP); 2) población y periodo de estudio, 3) calidad de los datos y 4) difusión de los resultados mediantes publicaciones. Se calculó el porcentaje anual de cambio constante de los indicadores analizándose su tendencia mediante el test de Cochran-Armitage. Resultados: El número de MP participantes aumentó de 164 en 2008-09 hasta 246 en ediciones posteriores. El porcentaje de médicos que reclutaron al menos un paciente experimentó un cambio anual significativo (PCA) del 15,33%. El porcentaje de pacientes reclutados incluidos en el análisis aumen- tó del 77% en 2008-09 a más del 95% en las siguientes ediciones (PCA=5,91%). El porcentaje de casos y controles participantes en cycEVA sobre el total de pacientes que contribuyeron al estudio europeo I-MOVE osciló entre el 23% en la edición piloto y 30% en la temporada 2011-12. Los resultados finales se difundieron en revistas científicas con un factor de impacto situado en el cuartil 2 y en 2010-11 y 2011-12 se publicaron resultados preliminares en revistas con un factor de impacto situado en el cuartil 1 (97 citas). Conclusiones: La experiencia del estudio cycEVA se reflejó en una mejora en la oportunidad e impacto de sus resultados, cruciales para orientar las recomendaciones anuales de vacunación antigripal