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  • 2015/16 I-MOVE/I-MOVE+ multicentre case control study in Europe: moderate vaccine effectiveness estimates against influenza A(H1N1)pdm09 and low estimates against lineage mismatched influenza B among children
    Publication . Kissling, Esther; Valenciano, Marta; Pozo, Francisco; Vilcu, Ana-Maria; Reuss, Annicka; Rizzo, Caterina; Larrauri, Amparo; Horváth, Judit Krisztina; Brytting, Mia; Domegan, Lisa; Korczyńska, Monika; Meijer, Adam; Machado, Ausenda; Ivanciuc, Alina; Višekruna Vučina, Vesna; van der Werf, Sylvie; Schweiger, Brunhilde; Bella, Antonino; Gherasim, Alin; Ferenczi, Annamária; Zakikhany, Katherina; O Donnell, Joan; Paradowska-Stankiewicz, Iwona; Dijkstra, Frederika; Guiomar, Raquel; Lazar, Mihaela; Kurečić Filipović, Sanja; Johansen, Kari; Moren, Alain; I-MOVE/I-MOVE+ study team
    Background:During the 2015/16 influenza season in Europe, the co-circulating influenza viruses were A(H1N1)pdm09 and B/Victoria, which was antigenically distinct from the B/Yamagata component in the trivalent influenza vaccine. Methods:We used the test negative design in a multicentre case–control study in twelve European countries to measure 2015/16 influenza vaccine effectiveness (VE) against medically-attended influenza-like illness (ILI) laboratory-confirmed as influenza. General practitioners swabbed a systematic sample of consulting ILI patients ainfluenza Vaccinend a random sample of influenza positive swabs were sequenced. We calculated adjusted VE against influenza A(H1N1)pdm09, A(H1N1)pdm09 genetic group 6B.1 and influenza B overall and by age group. Results: We included 11,430 ILI patients, of which 2272 were influenza A(H1N1)pdm09 and 2901 were influenza B cases. Overall VE against influenza A(H1N1)pdm09 was 32.9% (95% CI: 15.5-46.7). Among those aged 0–14, 15–64 and ≥65  years VE against A(H1N1)pdm09 was 31.9% (95% CI: -32.3-65.0), 41.4% (95%CI: 20.5-56.7) and 13.2% (95% CI: -38.0-45.3) respectively. Overall VE against influenza A(H1N1)pdm09 genetic group 6B.1 was 32.8% (95%CI: -4.1-56.7). Among those aged 0–14, 15–64 and ≥65 years VE against influenza B was -47.6% (95%CI: -124.9-3.1), 27.3% (95%CI: -4.6-49.4), and 9.3% (95%CI: -44.1-42.9) respectively. Conclusions: VE against influenza A(H1N1)pdm09 and its genetic group 6B.1 was moderate in children and adults, and low among individuals ≥65  years. VE against influenza B was low and heterogeneous among age groups. More information on effects of previous vaccination and previous infection are needed to understand the VE results against influenza B in the context of a mismatched vaccine.
    2018-06Artigo científico Acesso aberto Ver mais
  • Characteristics of SARS-CoV-2 variants of concern B.1.1.7, B.1.351 or P.1: data from seven EU/EEA countries, weeks 38/2020 to 10/2021
    Publication . Funk, Tjede; Pharris, Anastasia; Spiteri, Gianfranco; Bundle, Nick; Melidou, Angeliki; Carr, Michael; Gonzalez, Gabriel; Garcia-Leon, Alejandro; Crispie, Fiona; O’Connor, Lois; Murphy, Niamh; Mossong, Joël; Vergison, Anne; Wienecke-Baldacchino, Anke K.; Abdelrahman, Tamir; Riccardo, Flavia; Stefanelli, Paola; Di Martino, Angela; Bella, Antonino; Lo Presti, Alessandra; Casaca, Pedro; Moreno, Joana; Borges, Vítor; Isidro, Joana; Ferreira, Rita; Gomes, João Paulo; Dotsenko, Liidia; Suija, Heleene; Epstein, Jevgenia; Sadikova, Olga; Sepp, Hanna; Ikonen, Niina; Savolainen-Kopra, Carita; Blomqvist, Soile; Möttönen, Teemu; Helve, Otto; Gomes-Dias, Joana; Adlhoch, Cornelia
    We compared 19,207 cases of SARS-CoV-2 variant B.1.1.7/S gene target failure (SGTF), 436 B.1.351 and 352 P.1 to non-variant cases reported by seven European countries. COVID-19 cases with these variants had significantly higher adjusted odds ratios for hospitalisation (B.1.1.7/SGTF: 1.7, 95% confidence interval (CI): 1.0-2.9; B.1.351: 3.6, 95% CI: 2.1-6.2; P.1: 2.6, 95% CI: 1.4-4.8) and B.1.1.7/SGTF and P.1 cases also for intensive care admission (B.1.1.7/SGTF: 2.3, 95% CI: 1.4-3.5; P.1: 2.2, 95% CI: 1.7-2.8).
    2021-04Artigo científico Acesso aberto Ver mais
  • Effectiveness of influenza vaccine against influenza A in Europe in seasons of different A(H1N1)pdm09 and the same A(H3N2) vaccine components (2016-17 and 2017-18)
    Publication . Kissling, Esther; Pozo, Francisco; Buda, Silke; Vilcu, Ana-Maria; Rizzo, Caterina; Gherasim, Alin; Krisztina Horváth, Judit; Brytting, Mia; Domegan, Lisa; Meijer, Adam; Paradowska-Stankiewicz, Iwona; Machado, Ausenda; Višekruna Vučina, Vesna; Lazar, Mihaela; Johansen, Kari; Dürrwald, Ralf; van der Werf, Sylvie; Bella, Antonino; Larrauri, Amparo; Ferenczi, Annamária; Zakikhany, Katherina; O'Donnell, Joan; Dijkstra, Frederika; Bogusz, Joanna; Guiomar, Raquel; Kurečić Filipović, Sanja; Pitigoi, Daniela; Penttinen, Pasi; Valenciano, Marta; Gomez, Veronica; Kislaya, Irina; Nunes, Baltazar; I-MOVE/I-MOVE+ study team
    Introduction: Influenza A(H3N2) viruses predominated in Europe in 2016–17. In 2017–18 A(H3N2) and A(H1N1)pdm09 viruses co-circulated. The A(H3N2) vaccine component was the same in both seasons; while the A(H1N1)pdm09 component changed in 2017–18. In both seasons, vaccine seed A(H3N2) viruses developed adaptations/alterations during propagation in eggs, impacting antigenicity. Methods: We used the test-negative design in a multicentre primary care case-control study in 12 European countries to measure 2016–17 and 2017–18 influenza vaccine effectiveness (VE) against laboratory-confirmed influenza A(H1N1)pdm09 and A(H3N2) overall and by age group. Results: During the 2017–18 season, the overall VE against influenza A(H1N1)pdm09 was 59% (95% CI: 47–69). Among those aged 0–14, 15–64 and ≥65 years, VE against A(H1N1)pdm09 was 64% (95% CI: 37–79), 50% (95% CI: 28–66) and 66% (95% CI: 42–80), respectively. Overall VE against influenza A(H3N2) was 28% (95% CI: 17–38) in 2016–17 and 13% (95% CI: -15 to 34) in 2017–18. Among 0–14-year-olds VE against A(H3N2) was 28% (95%CI: -10 to 53) and 29% (95% CI: -87 to 73), among 15–64-year-olds 34% (95% CI: 18–46) and 33% (95% CI: -3 to 56) and among those aged ≥65 years 15% (95% CI: -10 to 34) and -9% (95% CI: -74 to 32) in 2016–17 and 2017–18, respectively. Conclusions: Our study suggests the new A(H1N1)pdm09 vaccine component conferred good protection against circulating strains, while VE against A(H3N2) was <35% in 2016–17 and 2017–18. The egg propagation derived antigenic mismatch of the vaccine seed virus with circulating strains may have contributed to this low effectiveness. A(H3N2) seed viruses for vaccines in subsequent seasons may be subject to the same adaptations; in years with lower than expected VE, recommendations of preventive measures other than vaccination should be given in a timely manner.
    2019-09-17Artigo científico Acesso aberto Ver mais
  • Estimates of pandemic influenza vaccine effectiveness in Europe, 2009-2010: results of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) multicentre case-control study
    Publication . Valenciano, Marta; Kissling, Esther; Cohen, Jean-Marie; Oroszi, Beatrix; Barret, Anne-Sophie; Rizzo, Caterina; Nunes, Baltazar; Pitigoi, Daniela; Larrauri Cámara, Amparro; Mosnier, Anne; Horvath, Judith K.; O'Donnell, Joan; Bella, Antonino; Guiomar, Raquel; Lupulescu, Emilia; Savulescu, Camelia; Ciancio, Bruno C.; Kramarz, Piotr; Moren, Alain
    A multicentre case-control study based on sentinel practitioner surveillance networks from seven European countries was undertaken to estimate the effectiveness of 2009-2010 pandemic and seasonal influenza vaccines against medically attended influenza-like illness (ILI) laboratory-confirmed as pandemic influenza A (H1N1) (pH1N1).
    2011-01Artigo científico Acesso aberto Ver mais
  • Exploring the effect of previous inactivated influenza vaccination on seasonal influenza vaccine effectiveness against medically attended influenza: results of the European I-MOVE multicentre test-negative case-control study, 2011/2012-2016/2017
    Publication . Valenciano, Marta; Kissling, Esther; Larrauri, Amparo; Nunes, Baltazar; Pitigoi, Daniela; O'Donnell, Joan; Reuss, Annicka; Horváth, Judit Krisztina; Paradowska-Stankiewicz, Iwona; Rizzo, Caterina; Falchi, Alessandra; Daviaud, Isabelle; Brytting, Mia; Meijer, Adam; Kaic, Bernard; Gherasim, Alin; Machado, Ausenda; Ivanciuc, Alina; Domegan, Lisa; Schweiger, Brunhilde; Ferenczi, Annamária; Korczyńska, Monika; Bella, Antonino; Vilcu, Ana-Maria; Mosnier, Anne; Zakikhany, Katherina; de Lange, Marit; Kurečić Filipovićović, Sanja; Johansen, Kari; Moren, Alain; I-MOVE primary care multicentre case-control team
    BACKGROUND: Results of previous influenza vaccination effects on current season influenza vaccine effectiveness (VE) are inconsistent. OBJECTIVES: To explore previous influenza vaccination effects on current season VE among population targeted for vaccination. METHODS: We used 2011/2012 to 2016/2017 I-MOVE primary care multicentre test-negative data. For each season, we compared current season adjusted VE (aVE) between individuals vaccinated and unvaccinated in previous season. Using unvaccinated in both seasons as a reference, we then compared aVE between vaccinated in both seasons, current only, and previous only. RESULTS: We included 941, 2645 and 959 influenza-like illness patients positive for influenza A(H1N1)pdm09, A(H3N2) and B, respectively, and 5532 controls. In 2011/2012, 2014/2015 and 2016/2017, A(H3N2) aVE point estimates among those vaccinated in previous season were -68%, -21% and -19%, respectively; among unvaccinated in previous season, these were 33%, 48% and 46%, respectively (aVE not computable for influenza A(H1N1)pdm09 and B). Compared to current season vaccination only, VE for both seasons' vaccination was (i) similar in two of four seasons for A(H3N2) (absolute difference [ad] 6% and 8%); (ii) lower in three of four seasons for influenza A(H1N1)pdm09 (ad 18%, 26% and 29%), in two seasons for influenza A(H3N2) (ad 27% and 39%) and in two of three seasons for influenza B (ad 26% and 37%); (iii) higher in one season for influenza A(H1N1)pdm09 (ad 20%) and influenza B (ad 24%). CONCLUSIONS: We did not identify any pattern of previous influenza vaccination effect. Prospective cohort studies documenting influenza infections, vaccinations and vaccine types are needed to understand previous influenza vaccinations' effects.
    2018-09Artigo científico Acesso aberto Ver mais
  • I-MOVE multicentre case-control study 2010/11 to 2014/15: Is there within-season waning of influenza type/subtype vaccine effectiveness with increasing time since vaccination?
    Publication . Kissling, Esther; Nunes, Baltazar; Robertson, Chris; Valenciano, Marta; Reuss, Annicka; Larrauri, Amparo; Cohen, Jean Marie; Oroszi, Beatrix; Rizzo, Caterina; Machado, Ausenda; Pitigoi, Daniela; Domegan, Lisa; Paradowska-Stankiewicz, Iwona; Buchholz, Udo; Gherasim, Alin; Daviaud, Isabelle; Horváth, Judit Krisztina; Bella, Antonino; Lupulescu, Emilia; O Donnell, Joan; Korczyńska, Monika; Moren, Alain; I-MOVE case–control study team
    Since the 2008/9 influenza season, the I-MOVE multicentre case-control study measures influenza vaccine effectiveness (VE) against medically-attended influenza-like-illness (ILI) laboratory confirmed as influenza. In 2011/12, European studies reported a decline in VE against influenza A(H3N2) within the season. Using combined I-MOVE data from 2010/11 to 2014/15 we studied the effects of time since vaccination on influenza type/subtype-specific VE. We modelled influenza type/subtype-specific VE by time since vaccination using a restricted cubic spline, controlling for potential confounders (age, sex, time of onset, chronic conditions). Over 10,000 ILI cases were included in each analysis of influenza A(H3N2), A(H1N1)pdm09 and B; with 4,759, 3,152 and 3,617 influenza positive cases respectively. VE against influenza A(H3N2) reached 50.6% (95% CI: 30.0-65.1) 38 days after vaccination, declined to 0% (95% CI: -18.1-15.2) from 111 days onwards. At day 54 VE against influenza A(H1N1)pdm09 reached 55.3% (95% CI: 37.9-67.9) and remained between this value and 50.3% (95% CI: 34.8-62.1) until season end. VE against influenza B declined from 70.7% (95% CI: 51.3-82.4) 44 days after vaccination to 21.4% (95% CI: -57.4-60.8) at season end. To assess if vaccination campaign strategies need revising more evidence on VE by time since vaccination is urgently needed.
    2016-04-21Artigo científico Acesso aberto Ver mais
  • National immunization strategies targeting migrants in six European countries
    Publication . Giambi, Cristina; Del Manso, Martina; Dalla Zuanna, Teresa; Riccardo, Flavia; Bella, Antonino; Caporali, Maria Grazia; Baka, Agoritsa; Caks-Jager, Nuska; Melillo, Tanya; Mexia, Ricardo; Petrović, Goranka; Declich, Silvia; Ali, Karam Adel; Dente, Maria Grazia; Iannazzo, Stefania; Kaić, Bernard; Napoli, Christian; Panagiotopoulos, Takis; Pereira, Filipa; CARE working group for the National Immunization Survey
    Over the last three years an unprecedented flow of migrants arrived in Europe. There is evidence that vaccine preventable diseases have caused outbreaks in migrant holding centres. These outbreaks can be favored by a combination of factors including low immunization coverage, bad conditions that migrants face during their exhausting journey and overcrowding within holding facilities. In 2017, we conducted an online survey in Croatia, Greece, Italy, Malta, Portugal and Slovenia to explore the national immunization strategies targeting irregular migrants, refugees and asylum seekers. All countries stated that a national regulation supporting vaccination offer to migrants is available. Croatia, Italy, Portugal and Slovenia offer to migrant children and adolescents all vaccinations included in the National Immunization Plan; Greece and Malta offer only certain vaccinations, including those against diphtheria-tetanus-pertussis, poliomyelitis and measles-mumps-rubella. Croatia, Italy, Malta and Portugal also extend the vaccination offer to adults. All countries deliver vaccinations in holding centres and/or community health services, no one delivers vaccinations at entry site. Operating procedures that guarantee the migrants' access to vaccination at the community level are available only in Portugal. Data on administered vaccines is available at the national level in four countries: individual data in Malta and Croatia, aggregated data in Greece and Portugal. Data on vaccination uptake among migrants is available at national level only in Malta. Concluding, although diversified, strategies for migrant vaccination are in place in all the surveyed countries and generally in line with WHO and ECDC indications. Development of procedures to keep track of migrants' immunization data across countries, development of strategies to facilitate and monitor migrants' access to vaccinations at the community level and collection of data on vaccination uptake among migrants should be promoted to meet existing gaps.
    2018-02-06Artigo científico Acesso restrito Ver mais
  • The epidemiological signature of influenza B virus and its B/Victoria and B/Yamagata lineages in the 21st century
    Publication . Caini, Saverio; Kusznierz, Gabriela; Garate, Verònica Vera; Wangchuk, Sonam; Thapa, Binay; de Paula Júnior, Francisco José; Ferreira de Almeida, Walquiria Aparecida; Njouom, Richard; Fasce, Rodrigo A.; Bustos, Patricia; Feng, Luzhao; Peng, Zhibin; Araya, Jenny Lara; Bruno, Alfredo; de Mora, Doménica; Barahona de Gámez, Mónica Jeannette; Pebody, Richard; Zambon, Maria; Higueros, Rocio; Rivera, Rudevelinda; Kosasih, Herman; Castrucci, Maria Rita; Bella, Antonino; Kadjo, Hervé A.; Daouda, Coulibaly; Makusheva, Ainash; Bessonova, Olga; Chaves, Sandra S.; Emukule, Gideon O.; Heraud, Jean-Michel; Razanajatovo, Norosoa H.; Barakat, Amal; El Falaki, Fatima; Meijer, Adam; Donker, Gé A.; Huang, Q. Sue; Wood, Tim; Balmaseda, Angel; Palekar, Rakhee; Arévalo, Brechla Moreno; Rodrigues, Ana Paula; Guiomar, Raquel; Lee, Vernon Jian Ming; Ang, Li Wei; Cohen, Cheryl; Treurnicht, Florette; Mironenko, Alla; Holubka, Olha; Bresee, Joseph; Brammer, Lynnette; Le, Mai T.Q.; Hoang, Phuong V.M.; El Guerche-Séblain, Clotilde; Paget, John; Global Influenza B Study team
    We describe the epidemiological characteristics, pattern of circulation, and geographical distribution of influenza B viruses and its lineages using data from the Global Influenza B Study. We included over 1.8 million influenza cases occurred in thirty-one countries during 2000-2018. We calculated the proportion of cases caused by influenza B and its lineages; determined the timing of influenza A and B epidemics; compared the age distribution of B/Victoria and B/Yamagata cases; and evaluated the frequency of lineage-level mismatch for the trivalent vaccine. The median proportion of influenza cases caused by influenza B virus was 23.4%, with a tendency (borderline statistical significance, p = 0.060) to be higher in tropical vs. temperate countries. Influenza B was the dominant virus type in about one every seven seasons. In temperate countries, influenza B epidemics occurred on average three weeks later than influenza A epidemics; no consistent pattern emerged in the tropics. The two B lineages caused a comparable proportion of influenza B cases globally, however the B/Yamagata was more frequent in temperate countries, and the B/Victoria in the tropics (p = 0.048). B/Yamagata patients were significantly older than B/Victoria patients in almost all countries. A lineage-level vaccine mismatch was observed in over 40% of seasons in temperate countries and in 30% of seasons in the tropics. The type B virus caused a substantial proportion of influenza infections globally in the 21st century, and its two virus lineages differed in terms of age and geographical distribution of patients. These findings will help inform health policy decisions aiming to reduce disease burden associated with seasonal influenza.
    2019-09-12Artigo científico Acesso aberto Ver mais
  • Vaccine effectiveness against influenza A in older adults and the effect of chronic conditions: results from the I-MOVE and VEBIS multicentre European hospital case-control studies, 2015/16-2023/24
    Publication . Rose, Angela Mary Catherine; Nicolay, Nathalie; Mazagatos, Clara; Martínez-Baz, Iván; Launay, Odile; De Mot, Laurane; Bella, Antonino; Lazar, Mihaela; Machado, Ausenda; Kuliešė, Monika; Abela, Stephen; Vučina, Vesna Višekruna; van Gageldonk-Lafeber, Rianne; Bino, Silvia; Dürrwald, Ralf; Paradowska-Stankiewicz, Iwona; Horváth, Judit Krisztina; Duffy, Róisín; Husa, Petr; McMenamin, Jim; Pozo, Francisco; Howard, Jennifer; Latorre-Millán, Miriam; Castilla, Jesús; Nguyen, Liem Binh Luong; Dauby, Nicolas; Riccardo, Flavia; Ivanciuc, Alina; Gomez, Verónica; Jančorienė, Ligita; Xuereb, Gerd; Petrović, Goranka; Marbus, Sierk; Vasili, Adela; Tolksdorf, Kristin; Bogusz, Joanna; Oroszi, Beatrix; Domegan, Lisa; Součková, Lenka; Marsh, Kimberley; Bacci, Sabrina; Kissling, Esther; I-MOVE & VEBIS Hospital Network teams
    Background: The Influenza - Monitoring Vaccine Effectiveness in Europe (I-MOVE/I-MOVE+) and Vaccine Effectiveness, Burden and Impact Studies (VEBIS) hospital networks have conducted seasonal multicentre, test-negative, case-control studies in Europe to measure influenza vaccine effectiveness (IVE) since 2015/16. We measured the effect of chronic conditions on VE of influenza A subtypes among older adults (≥ 65 years) using pooled-season data (2015/16-2023/24). Methods: Hospital teams swabbed patients with severe acute respiratory infection (SARI) within 7 days of symptom onset. Cases were RT-PCR positive for influenza A(H1N1)pdm09 or A(H3N2); controls negative for any influenza virus. We calculated overall pooled-season IVE against influenza A(H1N1)pdm09 and A(H3N2), adjusted for study site, sex, age and onset date; and stratified by number of and by each chronic condition (diabetes, heart disease, lung disease/asthma, immunosuppression, kidney disease, liver disease, cancer, obesity). We investigated interaction between vaccination and each condition. Results: We included 1805 A(H1N1)pdm09 cases with 16,329 controls; 2590 A(H3N2) cases with 14,920 controls, from 13 study sites (12 countries). Over all seasons, 63-67% cases and 70% controls had ≥ 2 chronic conditions. Against A(H1N1)pdm09, pooled-season IVE was 37% (95%CI: 29-44) overall; 49% (95%CI: 9-72), 30% (95%CI: 12-44) and 38% (95%CI: 29-46) in those with 0, 1, ≥ 2 chronic conditions. Most IVE point estimates were 34-45%, apart from immunosuppression (-7%), kidney disease (17%) and liver disease (54%), but 95% CIs overlapped. Significant interaction was observed for kidney disease (p = 0.02) and immunosuppression (p = 0.01). Against A(H3N2), pooled-season IVE was 17% (95%CI: 8-25) overall; 15% (95%CI: -26-42), 11% (95%CI: -8-27) and 18% (95%CI: 7-28) in those with 0, 1, ≥ 2 chronic conditions. Here, IVE point estimates ranged 13-25%, apart from immunosuppression (5%), kidney disease (6%) and liver disease (31%), although 95% CIs overlapped. There were no significant interactions. Conclusions: Pooled-season results suggest low-moderate VE against influenza A subtypes among older SARI patients; higher against A(H1N1)pdm09 than A(H3N2), with little evidence of chronic condition modifying effect, apart from kidney disease and immunosuppression. We stress the importance of developing improved influenza vaccines for specific populations, and encourage further research into the effect of chronic conditions on IVE in older adults.
    2025-11-03Artigo científico Acesso aberto Ver mais
  • Vaccine effectiveness against influenza A(H3N2) and B among laboratory‐confirmed, hospitalised older adults, Europe, 2017‐18: A season of B lineage mismatched to the trivalent vaccine
    Publication . Rose, Angela M.C.; Kissling, Esther; Gherasim, Alin; Casado, Itziar; Bella, Antonino; Launay, Odile; Lazăr, Mihaela; Marbus, Sierk; Kuliese, Monika; Syrjänen, Ritva; Machado, Ausenda; Kurečić Filipović, Sanja; Larrauri, Amparo; Castilla, Jesús; Alfonsi, Valeria; Galtier, Florence; Ivanciuc, Alina; Meijer, Adam; Mickiene, Aukse; Ikonen, Niina; Gómez, Verónica; Lovrić Makarić, Zvjezdana; Moren, Alain; Valenciano, Marta; I-MOVE Hospital study team
    Background: Influenza A(H3N2), A(H1N1)pdm09 and B viruses co-circulated in Europe in 2017-18, predominated by influenza B. WHO-recommended, trivalent vaccine components were lineage-mismatched for B. The I-MOVE hospital network measured 2017-18 seasonal influenza vaccine effectiveness (IVE) against influenza A(H3N2) and B among hospitalised patients (≥65 years) in Europe. Methods: Following the same generic protocol for test-negative design, hospital teams in nine countries swabbed patients ≥65 years with recent onset (≤7 days) severe acute respiratory infection (SARI), collecting information on demographics, vaccination status and underlying conditions. Cases were RT-PCR positive for influenza A(H3N2) or B; controls: negative for any influenza. "Vaccinated" patients had SARI onset >14 days after vaccination. We measured pooled IVE against influenza, adjusted for study site, age, sex, onset date and chronic conditions. Results: We included 3483 patients: 376 influenza A(H3N2) and 928 B cases, and 2028 controls. Most (>99%) vaccinated patients received the B lineage-mismatched trivalent vaccine. IVE against influenza A(H3N2) was 24% (95% CI: 2 to 40); 35% (95% CI: 6 to 55) in 65- to 79-year-olds and 14% (95% CI: -22 to 39) in ≥80-year-olds. Against influenza B, IVE was 30% (95% CI: 16 to 41); 37% (95% CI: 19 to 51) in 65- to 79-year-olds and 19% (95% CI: -7 to 38) in ≥80-year-olds. Conclusions: IVE against influenza B was similar to A(H3N2) in hospitalised older adults, despite trivalent vaccine and circulating B lineage mismatch, suggesting some cross-protection. IVE was lower in those ≥80 than 65-79 years. We reinforce the importance of influenza vaccination in older adults as, even with a poorly matched vaccine, it still protects one in three to four of this population from severe influenza.
    2020-05Artigo científico Acesso aberto Ver mais