High quality research is critical for evidence-based decision making in public health and fundamental to maintain progress and trust in immunization programs in Europe. In 2024 the European Centre for Disease Prevention and Control (ECDC) conducted an update of the 2020 systematic review to capture more recent evidence on of the efficacy, effectiveness of influenza vaccines in individuals aged 18 years and older in the prevention of laboratory-confirmed influenza. While this report was highly anticipated due to the strength of the protocol and processes put in place, during our assessment, we expressed two chief concerns. We are concerned by the grading of the evidence certainty applied and being unable to reproduce some data extracted in the report from the primary sources. While the systematic review benefited of strong methods and processes, the execution of the research protocol warrants revision due to the issues discussed. We encourage the ECDC to work towards an updated review within a reasonable time frame to avoid misinterpretation by decision-making bodies across Europe.

MD DSi Military Medical Academy Str G Sofiiski 3 Bulgaria

MD Family Physician 61 Plough Lane Wokingham RG40 1RQ England UK

MD FESPCH Prof General Practitioner Röntgenstr 2 82152 Martinsried Germany

MD Open Rome 57 rue d'Amsterdam 75008 Paris France

MD PhD Chair of the Dutch Influenza Foundation Paladijnenweg 30 3813 DJ Amersfoort Netherlands

MD PhD Chest Department Hospital Pulido Valente CHULN ULSSM Alameda das Linhas Torres 117 1769 001 Lisbon Portugal

MD PhD Children's Clinical Hospital Faculty of Medicine Transilvania University 56 Nicolae Bălcescu Street Braşov Romania

MD PhD Department for Infectious Diseases University of Zagreb School of Medicine Zagreb Croatia and Department for Acute Respiratory Infections Dr Fran Mihaljevic University Hospital for Infectious Diseases Zagreb Mirogojska 8 10000 Zagreb Croatia

MD PhD Department of Infectious Diseases Epidemiology National Institute of Public Health Srobarova 48 100 00 Prague 10 Prague Czech Republic and Department of Epidemiology and Biostatistics 3rd Faculty of Medicine Charles University Ruska 87 100 00 Prague 10 Prague Czech Republic

MD PhD Department of Pediatrics with Clinical Assessment Unit Medical University of Warsaw Zwirki i Wigury 63A Warszawa 02 091 Poland

MD PhD Emeritus Director and Scientific Advisor of the National Influenza Centre Hospital Clínico Universitario and University of Valladolid C Rondilla Sta Teresa s n 47010 Valladoild Spain

MD PhD Institute of Microbiology and Immunology Faculty of Medicine University of Belgrade Dr Subotica 1 11000 Belgrade Serbia

MD PhD MPH Department of Epidemiology Faculty of Public Health Slovak Medical University Limbová str 14 833 03 Bratislava Slovakia

MD PhD National Public Health Organization 3 5 Agrafon Street Marousi Athens 15123 Greece

MD University of Perugia Italian College of General Practitioner and Primary Care Piazzale Settimio Gambuli 1 06129 Perugia Italy

MD University of Tartu Institute of Clinical Medicine Department of Internal Medicine L Puusepa 8 50406 Tartu Estonia

Zobrazit více v PubMed

European Centre for Disease Prevention and Control. Stockholm: ECDC; 2020. Systematic review of the efficacy, effectiveness and safety of newer and enhanced seasonal influenza vaccines for the prevention of laboratory-confirmed influenza in individuals aged 18 years and over.

European Centre for Disease Prevention and Control. Stockholm: ECDC; 2024. Systematic review of the efficacy, effectiveness and safety of newer and enhanced seasonal influenza vaccines for the prevention of laboratory confirmed influenza in individuals aged 18 years and over.

Domnich A, Panatto D, Pariani E, et al. Relative effectiveness of the adjuvanted vs non-adjuvanted seasonal influenza vaccines against severe laboratory-confirmed influenza among hospitalized Italian older adults. Int J Infect Dis. 2022;125:164–9. doi: 10.1016/j.ijid.2022.10.041. PubMed DOI

Nealon J, Biering-Sørensen T, Crépey P, Harris R, Schaberg T, Chit A. Int J Infect Dis. 2024;145:107103. doi: 10.1016/j.ijid.2024.107103. PubMed DOI

Domnich A. Re: Influenza vaccine effectiveness in older adults: study methods, transparency and impacts on public health. Int J Infect Dis. 2024;145:107104. doi: 10.1016/j.ijid.2024.107104. PubMed DOI

DiazGranados CA, Dunning A, Kimmel M, et al. Efficacy of high-dose versus standard-dose influenza vaccine in older adults. N Engl J Med. 2014;371:635–45. doi: 10.1056/NEJMoa1315727. PubMed DOI

Dunkle M, Izikson R, Patriarca P, et al. Efficacy of recombinant influenza vaccine in adults 50 years of age or older. N Engl J Med. 2017;376:2427–36. doi: 10.1056/NEJMoa1608862. PubMed DOI

Mira-Iglesias A, López-Labrador FX, Baselga-Moreno V, et al. Influenza vaccine effectiveness against laboratory-confirmed influenza in hospitalised adults aged 60 years or older, Valencia Region, Spain, 2017/18 influenza season. Euro Surveill. 2019;24:1800461. doi: 10.2807/1560-7917.ES.2019.24.31.1800461. PubMed DOI PMC

Pebody R, Whitaker H, Zhao H, et al. Protection provided by influenza vaccine against influenza-related hospitalisation in ≥65-year-olds: early experience of introduction of a newly licensed adjuvanted vaccine in England in 2018/19. Vaccine. 2020;38:173–9. doi: 10.1016/j.vaccine.2019.10.032. PubMed DOI

Rondy M, Larrauri A, Casado I, et al. 2015/16 seasonal vaccine effectiveness against hospitalisation with influenza a(H1N1) pdm09 and B among elderly people in Europe: results from the I-MOVE+ project. Euro Surveill. 2017;22:30580. doi: 10.2807/1560-7917.ES.2017.22.30.30580. PubMed DOI PMC

Bellino S, Bella A, Puzelli S, et al. Moderate influenza vaccine effectiveness against A(H1N1) pdm09 virus, and low effectiveness against A(H3N2) subtype, 2018/19 season in Italy. Expert Rev Vaccines. 2019;18:1201–9. doi: 10.1080/14760584.2019.1688151. PubMed DOI

Pebody RG, Whitaker H, Ellis J, et al. End of season influenza vaccine effectiveness in primary care in adults and children in the United Kingdom in 2018/19. Vaccine. 2020;22:17–00306. doi: 10.2807/1560-7917.ES.2017.22.44.17-00306. PubMed DOI

Zimmerman RK, Patricia Nowalk M, Dauer K, Clarke L, Raviotta JM, Balasubramani GK. Vaccine effectiveness of recombinant and standard dose influenza vaccines against influenza related hospitalization using a retrospective test negative design. Vaccine. 2023;19:2177461. doi: 10.1080/21645515.2023.2177461. PubMed DOI PMC

Beran J, Reynales H, Poder A, et al. Prevention of influenza during mismatched seasons in older adults with an MF59-adjuvanted quadrivalent influenza vaccine: a randomised, controlled, multicentre, phase 3 efficacy study. Lancet Infect Dis. 2021;21:1027–37. doi: 10.1016/S1473-3099(20)30694-0. PubMed DOI

Johansen ND, Modin D, Nealon J, et al. NEJM Evid. 2023;2:EVIDoa2200206. doi: 10.1056/EVIDoa2200206. PubMed DOI

Health Information and Quality Authority. Draft Health Technology Assessment of use of an enhanced inactivated influenza vaccine for those aged 65 years and older in the Seasonal Influenza Vaccination Programme. [Accessed on: 30 May 2024]. Available at: https://www.hiqa.ie/sites/default/files/2024-05/Public-consultation-enhanced-flu-vaccines-for-65s.pdf.

Conseil Supérieur de la Santé. Bruxelles: CSS; 2024. Vaccination contre la grippe saisonnière - Saison hivernale 2024 - 2025. Avis n° 9831.