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Abstract: This study describes the epidemiological impact of meningococcal C conjugate vaccine on age groups targeted by this vaccination programme in Spain, and estimates high short-term vaccine effectiveness values under field conditions in the 4 years following its introduction. Meningococcal C conjugate vaccine has led to a substantial reduction in incidence of meningococcal serogroup C disease in Spain among age groups targeted for intervention nationwide. Disease surveillance in the 4 years since the vaccine was introduced has enabled vaccine effectiveness (VE) to be estimated. The vaccine registered high short-term VE values but there has been some loss of VE with time. Four years after vaccination, vaccine protection levels exceeded 94% in cohorts immunised during the campaign. Among children vaccinated in routine childhood immunisation programmes, however, long-term VE loss was greater. Accordingly, there is a need for ongoing re-evaluation of VE and ascertainment of long-term vaccine protection. The findings reported would allow to decide on the advisability of revising current vaccination guidelines. [Copyright &y& Elsevier]

This study sought to describe influenza vaccination coverages for different Spanish population subgroups, stressing the analysis of vaccination-related factors in subjects aged 50–64 years and estimating the possible beneficial effect of extending universal vaccination to this age group.A total of 6400 surveys, targeting subjects over the age of 16 years and drawn from the 1997 Spanish National Health Survey, were used for study purposes.Influenza coverage was observed to rise significantly with age, and the reason cited by most subjects for seeking vaccination was medical indication. Coverage of the 50–64 age group was 21.6% (95% CI 19.4–23.8) and the variables associated with a greater probability of being vaccination were: residence in towns or cities with <10,000 inhabitants (OR 1.45); monthly income of less than €600 (OR 1.71); and presence of associated chronic disease (OR 3.07.) It is estimated that in Spain, 524,514 (40.7%) persons aged 50–64 years with associated chronic disease receive and 764,218 persons aged 50–64 years with associated chronic disease do not receive influenza vaccine.We conclude that the extremely high number of subjects in the 50–64 age range susceptible to influenza-related complications each year constitutes good grounds for universal vaccination being extended to said age group. [Copyright &y& Elsevier]

Within influenza vaccine effectiveness (VE) studies at primary care level with a laboratory-confirmed outcome, clinical case definitions for recruitment of patients can vary. We used the 2022–23 VEBIS primary care European multicentre study end-of-season data to evaluate whether the clinical case definition affected IVE estimates. We estimated VE using a multicentre test-negative case-control design. We measured VE against any influenza and influenza (sub)types, by age group (0–14, 15–64, ≥65 years) and by influenza vaccine target group, using logistic regression. We estimated IVE among patients meeting the European Union (EU) acute respiratory infection (ARI) case definition and among those meeting the EU influenza-like illness (ILI) case definition, including only sites providing information on specific symptoms and recruiting patients using an ARI case definition (as the EU ILI case definition is a subset of the EU ARI one). We included 24 319 patients meeting the EU ARI case definition, of whom 21 804 patients (90 %) meet the EU ILI case definition, for the overall pooled VE analysis against any influenza. The overall and influenza (sub)type-specific VE varied by ≤2 % between EU ILI and EU ARI populations. Among all analyses, we found similar VE estimates between the EU ILI and EU ARI populations, with few (10%) additional non-ILI ARI patients recruited. These results indicate that VE in the 2022–23 influenza season was not affected by use of a different clinical case definition for recruitment, although we recommend investigating whether this holds true for next seasons. [ABSTRACT FROM AUTHOR]

In Europe, annual influenza vaccination is recommended to elderly. From 2011 to 2014 and in 2015–16, we conducted a multicentre test negative case control study in hospitals of 11 European countries to measure influenza vaccine effectiveness (IVE) against laboratory confirmed hospitalised influenza among people aged ≥65 years. We pooled four seasons data to measure IVE by past exposures to influenza vaccination. We swabbed patients admitted for clinical conditions related to influenza with onset of severe acute respiratory infection ≤7 days before admission. Cases were patients RT-PCR positive for influenza virus and controls those negative for any influenza virus. We documented seasonal vaccination status for the current season and the two previous seasons. We recruited 5295 patients over the four seasons, including 465A(H1N1)pdm09, 642A(H3N2), 278 B case-patients and 3910 controls. Among patients unvaccinated in both previous two seasons, current seasonal IVE (pooled across seasons) was 30% (95%CI: −35 to 64), 8% (95%CI: −94 to 56) and 33% (95%CI: −43 to 68) against influenza A(H1N1)pdm09, A(H3N2) and B respectively. Among patients vaccinated in both previous seasons, current seasonal IVE (pooled across seasons) was −1% (95%CI: −80 to 43), 37% (95%CI: 7–57) and 43% (95%CI: 1–68) against influenza A(H1N1)pdm09, A(H3N2) and B respectively. Our results suggest that, regardless of patients’ recent vaccination history, current seasonal vaccine conferred some protection to vaccinated patients against hospitalisation with influenza A(H3N2) and B. Vaccination of patients already vaccinated in both the past two seasons did not seem to be effective against A(H1N1)pdm09. To better understand the effect of repeated vaccination, engaging in large cohort studies documenting exposures to vaccine and natural infection is needed. [ABSTRACT FROM AUTHOR]

Background: The omicron (B.1.1.529) variant of SARS-CoV-2 has increased capacity to elude immunity and cause breakthrough infections. The aim of this study was to estimate the effectiveness of mRNA-based vaccine boosters (third dose) against infection with the omicron variant by age, sex, time since complete vaccination, type of primary vaccine, and type of booster.Methods: In this nationwide cohort study, we linked data from three nationwide population registries in Spain (Vaccination Registry, Laboratory Results Registry, and National Health System registry) to select community-dwelling individuals aged 40 years or older, who completed their primary vaccine schedule at least 3 months before the start of follow-up, and had not tested positive for SARS-CoV-2 since the start of the pandemic. On each day between Jan 3, and Feb 6, 2022, we matched individuals who received a booster mRNA vaccine and controls of the same sex, age group, postal code, type of vaccine, time since primary vaccination, and number of previous tests. We estimated risk of laboratory-confirmed SARS-CoV-2 infection using the Kaplan-Meier method and compared groups using risk ratios (RR) and risk differences. Vaccine effectiveness was calculated as one minus RR.Findings: Between Jan 3, and Feb 6, 2022, 3 111 159 matched pairs were included in our study. Overall, the estimated effectiveness from day 7 to 34 after a booster was 51·3% (95% CI 50·2-52·4). Estimated effectiveness was 52·5% (51·3-53·7) for an mRNA-1273 booster and 46·2% (43·5-48·7) for a BNT162b2 booster. Effectiveness was 58·6% (55·5-61·6) if primary vaccination had been with ChAdOx1 nCoV-19 (Oxford-AstraZeneca), 55·3% (52·3-58·2) with mRNA-1273 (Moderna), 49·7% (48·3-51·1) with BNT162b2 (Pfizer-BioNTech), and 48·0% (42·5-53·7) with Ad26.COV2.S (Janssen). Estimated effectiveness was 43·6% (40·0-47·1) when the booster was administered between 151 days and 180 days after complete vaccination and 52·2% (51·0-53·3) if administered more than 180 days after primary scheduled completion.Interpretation: Booster mRNA vaccine-doses were moderately effective in preventing infection with the omicron variant of SARS-CoV-2 for over a month after administration, which indicates their suitability as a strategy to limit the health effects of COVID-19 in periods of omicron variant domination. Estimated effectiveness was higher for mRNA-1273 compared with BNT162b2 and increased with time between completed primary vaccination and booster.Funding: None. [ABSTRACT FROM AUTHOR]

Introduction The agreement between interim and final influenza vaccine effectiveness (VE) estimates would support the use of interim assessments as a proxy for final VE results to guide health authorities in influenza prevention. We aimed to compare interim/final VE estimates in Spain. Methods We used a test-negative case-control study (cycEVA) for 2010/11–2013/14 seasons. Sensitivity analyses were carried out by type/subtype of influenza virus and by target groups for vaccination. Results In general, interim estimates were higher compared to end-season estimates. Interim and final VE differences were higher for the target groups compared to all population. Subtype-specific interim/final VE estimates showed greater concordance (3–13%) than for any virus (7–24%). Conclusion In Spain, interim influenza VE estimates over 2010–2014 were a good proxy of the final protection of the vaccine. Interim and final estimates showed greater concordance for all population and if performed subtype-specific. [ABSTRACT FROM AUTHOR]

• Seasonal influenza vaccine programmes usually target at-risk and older individuals. • We used an age-structured dynamic-transmission model for eight European settings. • Older people benefit from adjuvanted or high-dose trivalent or quadrivalent vaccines. • Adopting mass paediatric influenza vaccination is also likely to be cost-effective. • Results rest on vaccine costs, willingness to vaccinate and unknown long-term effects. Despite seasonal influenza vaccination programmes in most countries targeting individuals aged ≥ 65 (or ≥ 55) years and high risk-groups, significant disease burden remains. We explored the impact and cost-effectiveness of 27 vaccination programmes targeting the elderly and/or children in eight European settings (n = 205.8 million). We used an age-structured dynamic-transmission model to infer age- and (sub-)type-specific seasonal influenza virus infections calibrated to England, France, Ireland, Navarra, The Netherlands, Portugal, Scotland, and Spain between 2010/11 and 2017/18. The base-case vaccination scenario consisted of non-adjuvanted, non-high dose trivalent vaccines (TV) and no universal paediatric vaccination. We explored i) moving the elderly to "improved" (i.e., adjuvanted or high-dose) trivalent vaccines (iTV) or non-adjuvanted non-high-dose quadrivalent vaccines (QV); ii) adopting mass paediatric vaccination with TV or QV; and iii) combining the elderly and paediatric strategies. We estimated setting-specific costs and quality-adjusted life years (QALYs) gained from the healthcare perspective, and discounted QALYs at 3.0%. In the elderly, the estimated numbers of infection per 100,000 population are reduced by a median of 261.5 (range across settings: 154.4, 475.7) when moving the elderly to iTV and by 150.8 (77.6, 262.3) when moving them to QV. Through indirect protection, adopting mass paediatric programmes with 25% uptake achieves similar reductions in the elderly of 233.6 using TV (range: 58.9, 425.6) or 266.5 using QV (65.7, 477.9), with substantial health gains from averted infections across ages. At €35,000/QALY gained, moving the elderly to iTV plus adopting mass paediatric QV programmes provides the highest mean net benefits and probabilities of being cost-effective in all settings and paediatric coverage levels. Given the direct and indirect protection, and depending on the vaccine prices, model results support a combination of having moved the elderly to an improved vaccine and adopting universal paediatric vaccination programmes across the European settings. [ABSTRACT FROM AUTHOR]

Introduction The 2014/15 influenza season in Spain was dominated by the circulation of drifted A(H3N2) and co-circulation of B viruses. We present the final estimates of influenza vaccine effectiveness (IVE) against confirmed influenza A(H3N2) and B its evolution along the season and with time since vaccination. Methods We used data collected on influenza like illness patients (ILI), systematically swabbed for the presence of influenza viruses within the Spanish Influenza Sentinel Surveillance System (SISS) and a restricted observational study (cycEVA). We used a test negative case–control design to compare influenza confirmed cases with negative controls. We estimated the IVE through a logistic regression model adjusting for potential confounders. The evolution of IVE was studied in early and late stages of the epidemic, and in different time intervals between receiving influenza vaccination and the onset of symptoms. Results At the end of the season we have found low and moderate IVE point estimates against influenza A(H3N2) and B, respectively, in all ages and target groups for vaccination. An IVE decreased from an early value of 37% to a late of −76% against influenza A(H3N2), and similarly, 84% vs −4% against Influenza B. When the onset of symptoms occurred more than three months after vaccination, the decrease of IVE was slower and milder against influenza B than against influenza A(H3N2). No significant change in the percentage of circulating drifted influenza A(H3N2) strains belonging to the 3c.2a and 3c.3a clades could be identified through the season. Conclusions In a season dominated by drifted A(H3N2) circulating virus, the vaccine offered little or no protection against A(H3N2) infection but had a moderate protective effect against influenza B. Efforts should be put in developing influenza vaccines that maintain their protective capabilities throughout the season and could stimulate a potentially broad immune response against diverse influenza strains. [ABSTRACT FROM AUTHOR]

Abstract: Background: Pandemic influenza A (H1N1) 2009 virus appeared in Spain on April 25, 2009 for the first time. This new virus was adamantane-resistant but it was sensitive to neuraminidase (NA) inhibitors oseltamivir and zanamivir. Objectives: To detect oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses by the Spanish Influenza Surveillance System (SISS) and a possible spread of oseltamivir-resistant viruses in Spain since starting of the pandemic situation. Study design: A total of 1229 respiratory samples taken from 413 severe and 766 non-severe patients with confirmed viral detection of pandemic influenza A (H1N1) 2009 viruses from different Spanish regions were analyzed for the specific detection of the H275Y mutation in NA between April 2009 and May 2010. Results: H275Y NA substitution was found in 8 patients infected with pandemic influenza A (H1N1) 2009 viruses collected in November and December 2009 and in January 2010. All oseltamivir-resistant viruses were detected in severe patients (8/413, 1.93%) who previously received treatment with oseltamivir. Six of these patients were immunocompromised. Conclusion: In Spain, the number of oseltamivir-resistant pandemic influenza A (H1N1) 2009 viruses is until now very low. No evidence for any spread of oseltamivir-resistant H1N1 viruses is achieved in our Country. [Copyright &y& Elsevier]

Abstract: We conducted a case–control and screening method studies to estimate influenza vaccine effectiveness (IVE) in the age group ≥65 years, based on the Spanish Influenza Sentinel Surveillance System (SISSS). Cases (influenza laboratory-confirmed) were compared to influenza-negative ILI patients (test-negative) and patients without ILI since the beginning of the season (non-ILI). For the screening method, cases’ vaccination coverage was compared to the vaccination coverage of the GPs’ catchment population. The results suggested a protective effect of the vaccine against laboratory-confirmed influenza in elderly in 2008–2009. The screening method and the test-negative control designs enable estimating IVE using exclusively SISSS data. [Copyright &y& Elsevier]