Vaccine effectiveness against COVID-19 hospitalisation in adults (≥ 20 years) during Alpha- and Delta-dominant circulation: I-MOVE-COVID-19 and VEBIS SARI VE networks, Europe, 2021

Angela Rose, Nathalie Nicolay, Virginia Sandonis Martín, Clara Mazagatos, Goranka Petrović, Annabel F. Niessen, Ausenda Machado, Odile Launay, Sarah Denayer, Lucie Seyler, Joaquin Baruch, Cristina Burgui, Isabela I Loghin, Lisa Domegan, Roberta Vaikutyte, Petr Husa, George Panagiotakopoulos, Nassera Aouali, Ralf Dürrwald, Jennifer Howard Francisco Pozo, Bartolomé Sastre-Palou, Diana Nonković, Mirjam J Knol, Irina Kislaya, Liem binh Luong Nguyen, Nathalie Bossuyt, Thomas Demuyser, Aušra Džiugytė, Iván Martínez-Baz, Corneliu Popescu, Róisín Duffy, Monika Kuliešė, Lenka Součková, Stella Michelaki, Marc Simon, Janine Reiche, María Teresa Otero-Barrós, Zvjezdana Lovrić Makarić, Patricia CJL Bruijning-Verhagen, Verónica Gomez, Zineb Lesieur, Cyril Barbezange, Els Van Nedervelde, Maria-Louise Borg, Jesús Castilla, Mihaela Lazar, Joan O’Donnell, Indrė Jonikaite, Regina Demlová, Marina Amerali, Gil Wirtz, Kristin Tolksdorf, Marta Valenciano, Sabrina Bacci, Esther Kissling

Research output: Contribution to journalArticlepeer-review


Introduction: Two large multicentre European hospital networks have estimated vaccine effectiveness (VE) against COVID-19 since 2021. Aim: We aimed to measure VE against PCR-confirmed SARS-CoV-2 in hospitalised severe acute respiratory illness (SARI) patients≥20 years, combining data from these networks during Alpha (March–June)- and Delta (June–December)dominant periods, 2021. Methods: Forty-six participating hospitals across 14 countries follow a similar generic protocol using the test-negative case–control design. We defined complete primary series vaccination (PSV) as two doses of a two-dose or one of a single-dose vaccine≥14 days before onset. Results: We included 1,087 cases (538 controls) and 1,669 cases (1,442 controls) in the Alpha- and Delta-dominant periods, respectively. During the Alpha period, VE against hospitalisation with SARSCoV2 for complete Comirnaty PSV was 85% (95% CI: 69–92) overall and 75% (95% CI: 42–90) in those aged≥80 years. During the Delta period, among SARI patients≥20 years with symptom onset≥150 days from last PSV dose, VE for complete Comirnaty PSV was 54% (95% CI: 18–74). Among those receiving Comirnaty PSV and mRNA booster (any product)≥150 days after last PSV dose, VE was 91% (95% CI: 57–98). In time-since-vaccination analysis, complete all-product PSV VE was > 90% in those with their last dose < 90 days before onset; ≥ 70% in those 90–179 days before onset. Conclusions: Our results from this EU multi-country hospital setting showed that VE for complete PSV alone was higher in the Alpha-than the Delta-dominant period, and addition of a first booster dose during the latter period increased VE to over 90%.

Original languageEnglish
Article number2300186
Number of pages16
Issue number47
Publication statusPublished - 23 Nov 2023

Bibliographical note

Funding Information:
Study teams are very grateful to all patients, physicians, laboratory teams, and national or regional epidemiologists who have contributed to the study. The Spanish team thanks all the participants in the SiVIRA Group for Surveillance and vaccine effectiveness in Spain, including everyone involved in data collection and notification at the sentinel hospitals, laboratories, and public health units of all participating Autonomous Regions. Participating laboratories submitted their sequences to GISAID ( for easy sharing with the central laboratory in Madrid.

Publisher Copyright:
© 2023 European Centre for Disease Prevention and Control (ECDC). All rights reserved.


  • SARS-CoV-2
  • Alpha
  • Delta
  • Hospital
  • Vaccine effectivness
  • Europe


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