Interim 2023/24 influenza A vaccine effectiveness: VEBIS European primary care and hospital multicentre studies, September 2023 to January 2024.

Influenza A viruses circulated in Europe from September 2023 to January 2024, with influenza A(H1N1)pdm09 predominance. We provide interim 2023/24 influenza vaccine effectiveness (IVE) estimates from two European studies, covering 10 countries across primary care (EU-PC) and hospital (EU-H) settings. Interim IVE was higher against A(H1N1)pdm09 than A(H3N2): EU-PC influenza A(H1N1)pdm09 IVE was 53% (95% CI: 41 to 63) and 30% (95% CI: -3 to 54) against influenza A(H3N2). For EU-H, these were 44% (95% CI: 30 to 55) and 14% (95% CI: -32 to 43), respectively.

Acute flaccid paralysis (AFP) surveillance: challenges and opportunities from 18 years' experience, Spain, 1998 to 2015.

Acute flaccid paralysis (AFP) surveillance is key for global polio eradication. It allows detecting poliovirus (PV) reintroductions from endemic countries. This study describes AFP surveillance in Spain from 1998 to 2015. During this time, 678 AFP cases were reported to the Spanish National Surveillance Network. The mean notification rate was 0.58 AFP cases/100,000 population under 15 years old (range: 0.45/100,000-0.78/100,000). Two periods (P) are described: P1 (1998-2006) with the AFP notification rate ranging from 0.66/100,000 to 0.78/100,000, peaking in 2001 (0.84/100,000); and P2 (2007-2015) when the AFP rate ranged from 0.43/100,000 to 0.57/100,000, with the lowest rate in 2009 (0.31/100,000). No poliomyelitis cases were caused by wild PV infections, although two Sabin-like PVs and one imported vaccine-derived PV-2 were detected. Overall, 23 (3.4%) cases met the hot case definition. Most cases were clinically diagnosed with Guillain-Barré syndrome (76.9%; 504/655). The adequate stool collection rate ranged from 33.3% (7/21) to 72.5% (29/40). The annual proportion of AFP cases with non-polio enterovirus findings varied widely across the study period. AFP surveillance with laboratory testing for non-polio enteroviruses must be maintained and enhanced both to monitor polio eradication and to establish sensitive surveillance for prompt detection of other enteroviruses causing serious symptoms.

Estimated Impact of Nirsevimab on the Incidence of Respiratory Syncytial Virus Infections Requiring Hospital Admission in Children < 1 Year, Weeks 40, 2023, to 8, 2024, Spain.

BACKGROUND: Data from the sentinel surveillance system of severe acute respiratory infections in Spain were used to estimate the impact of administration of nirsevimab to children born from 1 April 2023 onwards. METHODS: Estimated RSV hospitalisations in < 1-year-olds during weeks 40, 2023, to 8, 2024, were compared to the number that would be expected after accounting for the background change in RSV circulation in the 2023/24 season, compared to 2022/23. RESULTS: We estimated 9364-9875 RSV hospitalisations less than expected, corresponding to a 74%-75% reduction.

COVID-19 vaccine effectiveness against hospitalization due to SARS-CoV-2: A test-negative design study based on Severe Acute Respiratory Infection (SARI) sentinel surveillance in Spain.

BACKGROUND: With the emergence of SARS-CoV-2, influenza surveillance systems in Spain were transformed into a new syndromic sentinel surveillance system. The Acute Respiratory Infection Surveillance System (SiVIRA in Spanish) is based on a sentinel network for acute respiratory infection (ARI) surveillance in primary care and a network of sentinel hospitals for severe ARI (SARI) surveillance in hospitals. METHODS: Using a test-negative design and data from SARI admissions notified to SiVIRA between January 1 and October 3, 2021, we estimated COVID-19 vaccine effectiveness (VE) against hospitalization, by age group, vaccine type, time since vaccination, and SARS-CoV-2 variant. RESULTS: VE was 89% (95% CI: 83-93) against COVID-19 hospitalization overall in persons aged 20 years and older. VE was higher for mRNA vaccines, and lower for those aged 80 years and older, with a decrease in protection beyond 3 months of completing vaccination, and a further decrease after 5 months. We found no differences between periods with circulation of Alpha or Delta SARS-CoV-2 variants, although variant-specific VE was slightly higher against Alpha. CONCLUSIONS: The SiVIRA sentinel hospital surveillance network in Spain was able to describe clinical and epidemiological characteristics of SARI hospitalizations and provide estimates of COVID-19 VE in the population under surveillance. Our estimates add to evidence of high effectiveness of mRNA vaccines against severe COVID-19 and waning of protection with time since vaccination in those aged 80 or older. No substantial differences were observed between SARS-CoV-2 variants (Alpha vs. Delta).

[Influenza a (H1N1) virus infection in humans: review to 30th October 2009]. / Infección en humanos por virus de la gripe A(H1N1): revisión al 30 de octubre de 2009.

Since human infection by a novel influenza virus A H1N1 of swine origin was reported in April 2009, the virus has spread worldwide causing a pandemic. In the Southern Hemisphere, the first pandemic wave has taken place, coinciding with Austral Winter. In the Northern Hemisphere, transmission has been sustained under the basal level of epidemic until the first weeks of October, when incidence rates have risen up to the pidemic level in some countries, including Spain. This work reviews the differential characteristics of this novel virus in terms of pathogenicity, clinical syndrome and epidemiology, as well as the diagnostic, prophylactic and therapeutic procedures available; information we consider relevant to minimize the impact of this new pandemic in our area.

[Infection by the pandemic virus (H1N1) 2009 in Andalusia]. / Infección por virus pandémico (H1N1) 2009 en Andalucía.

In April 2009, in response to the WHO's alert due to the existence of human infection cases with a new AH1N1 influenza virus, known as swine flu, Andalusian Health Authorities trigger an specific action plan. The surveillance actions developped provided us with appropriate clinical, epidemiological and virological characteristics of the disease. During the first few days, contingency plans were set up based on epidemiological surveillance and outbreak control measures were adopted through early alert and rapid response systems. After phase 6 was declared, influenza sentinel and severe cases surveillance were used in order to plan healthcare services, to reduce transmission and to identify and protect the most vulnerable population groups. Behaviour of pandemic influenza in Andalusia was similar to that observed in the rest of the world. Atack rate was similar to a seasonal flu and the peak was reached at the 46th/2009 week. Most of them were mild cases and affected particularly to young people. The average age of hospitalised patients was 32. Prior pulmonary disease, smoking and morbid obesity (BMI > 40) were the most common pathologies and risk factors in severe cases. An impact scenario of pandemic wave in Andalusia, with an expected attack rate from 2 to 5%, was prepared considering watt observed in the southern hemisphere. Characteristics of the epidemic concerning its extent, severity and mortality rate were adjusted to this scenario.

[Changes in Hepatitis A epidemiological pattern in Andalucía: 2007-2017]. / Cambios en el patrón epidemiológico de la Hepatitis A en Andalucía: 2007-2017.

OBJECTIVE: Sexual transmission of hepatitis A (HAV) is documented, mainly by risk behaviors in men who have sex with men (MSM). There have been HAV outbreaks in MSM in countries of the European Union in the last years. The aim of this work was to study HAV epidemiology in Andalusia in the last 10 years (2007-2017) and the outbreaks among MSM in this period. METHODS: Retrospective descriptive study of HAV cases reported in the Andalusia Epidemiological Surveillance System between January 2007 and May 2017. We calculated the annual incidence rate per 100000 habitants. We studied case distribution for gender and age. We used the male-female ratio as an indirect marker for MSM. RESULTS: The mean annual incidence rate in the study period was 4.09 cases per 100000 habitants, with a difference by sex: 4.7 per 100000 men and 2.53 per 100000 women. Two large outbreaks were detected in this period: one in 2008-2009 and another in 2016-2017. The epidemiological characteristics of these outbreaks differ from the classical pattern of the disease, affecting young MSM with associated sexual risk behaviors. CONCLUSIONS: MSM play a fundamental role in recent outbreaks of HAV. For disease control we must carry out a different strategy, assessing the introduction of systematic vaccination.

OBJETIVO: La trasmisión sexual de la hepatitis A (VHA) está documentada, principalmente en conduc- tas de riesgo en hombres que tienen sexo con hombres (HSH). En los últimos años están apareciendo brotes de VHA en HSH en países de la Unión Europea. El objetivo del trabajo fue estudiar la epidemiología del VHA en Andalucía en los últimos 10 años (2007-2017) y la de los brotes ocurridos en HSH en dicho periodo. METODOS: Estudio descriptivo retrospectivo de los casos de VHA declarados en el Sistema de Vigilancia Epidemiológica de Andalucía (SVEA) entre enero de 2007 y mayo de 2017. Se calculó la tasa de incidencia anual por 100.000 habitantes. Se estudió la distribución de los casos por grupo de edad y sexo. Se usó la razón hombre-mujer, como marcador indirecto de los HSH. RESULTADOS: La tasa de incidencia media anual en el periodo de estudio fue 4,09 casos por 100.000 habitantes, con una diferencia según sexo: 4,7 por 100.000 hombres y 2,53 por 100.000 mujeres. Aparecieron dos grandes brotes en este periodo: uno en 2008-2009 y otro en 2016-2017. Las características epidemiológicas de estos brotes difirieron del patrón clásico de la enfermedad, afectando a HSH jóvenes, colectivo que se asocia con conductas sexuales de riesgo. CONCLUSIONES: Los HSH tienen un papel fundamental en los brotes de VHA aparecidos recientemente. Para el control de la enfermedad debemos realizar una estrategia diferente, valorando la introducción de la vacunación sistemática.

[Outbreaks of Measles in Andalusia, Spain, during the Period 2010-2015]. / Brotes epidémicos de sarampión en Andalucía durante el período 2010-2015.

The Andalusian Surveillance Epidemiological System (SVEA) controls and investigates any notification of measles or any other communicable disease. The aim of this article is to describe the epidemiological characteristics of measles outbreaks occurred in Andalusia in the last five years (2010-2015) and their control measures. In this period three outbreaks were reported: the first one started in Granada in 2010 in a community of objectors to vaccination. Control measures of measles protocol of SVEA were adopted (case isolation, identification and contacts immunization), including judicial measures among the group who refused the vaccination. The second outbreak started in Seville in 2011 in an "area in need of social transformation" and it spread throughout the region. The routine vaccination coverage review was introduced within the surveillance system after those outbreaks, identifying the most vulnerable people. During the first six months of 2015, a small outbreak, of 15 cases, occurred in Granada. The outbreak was controlled mainly due to the early intervention, the health measures adopted in the schools and health centres involved and the high vaccination coverage achieved in the population.

[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.