We conducted a multicentre test-negative case-control study covering the period from October 2023 to January 2024 among adult patients aged ≥18 years hospitalised with severe acute respiratory infection in Europe. We provide early estimates of the effectiveness of the newly adapted XBB.1.5 COVID-19 vaccines against PCR-confirmed SARS-CoV-2 hospitalisation. Vaccine effectiveness was 48% overall, ranging between 68% at 14–29 days and 40% at 60–105 days post vaccination. The adapted XBB.1.5 COVID-19 vaccines conferred protection against COVID-19 hospitalisation in the first 3.5 months post vaccination, with VE >70% in older adults (≥65 years) up to 1 month post vaccination.

Using a common protocol across seven countries in the European Union/European Economic Area, we estimated XBB.1.5 monovalent vaccine effectiveness (VE) against COVID-19 hospitalisation and death in ≥65-year-olds, during October-November 2023. We linked electronic records to construct retrospective cohorts and used Cox models to estimate adjusted Hazard Ratios and derive VE. VE for COVID-10 hospitalisation and death was, respectively, 67% (95%CI: 60-72) and 68% (95%CI: 44-82) in 65–79-year-olds, and 64% (95%CI: 49-75) and 74% (95%CI: 56-85) in ≥80-year-olds. Results indicate that periodic vaccination of individuals ≥65 years has an ongoing benefit, and support the current vaccination strategies in the EU/EEA.

We conducted a multicentre hospital-based test-negative case–control study to measure vaccine effectiveness (VE) against PCR-confirmed influenza in adult patients with severe acute respiratory infection (SARI) during the 2022/23 influenza season in Europe. Among 5547 SARI patients ≥18 years, 2963 (53%) were vaccinated against influenza. Overall VE against influenza A(H1N1)pdm09 was 11% (95%CI: -23–36); 20% (95%CI: -4–39) against A(H3N2) and 56% (95%CI: 22–75) against B. During the 2022/23 season, while VE against hospitalisation with influenza B was >55%, it was ≤20% for influenza A subtypes. While influenza vaccination should be a priority for the upcoming season, improved vaccines against influenza are needed.

Background: Within the ECDC-VEBIS project, we prospectively monitored vaccine effectiveness (VE) against COVID-19 hospitalisation and COVID-19-related death, using electronic health registries (EHR), between October 2021 and November 2022, in community-dwelling residents aged 65–79 and ≥80-years in six European countries. Methods: EHR linkage was used to construct population cohorts in Belgium, Denmark, Luxembourg, Navarre (Spain), Norway and Portugal. Using a common protocol, for each outcome (hospitalisation and death), VE was estimated monthly over eight-week follow-up periods, allowing one month-lag for data consolidation. Cox proportional-hazards regression models were used to estimate adjusted hazard ratios (aHR) and VE=(1 – aHR) x100. Site-specific estimates were pooled using random-effects meta-analysis. Results: For ≥80-years, VE against COVID-19 hospitalisation decreased from 66.9% (95%CI: 60.1; 72.6) to 36.1% (95%CI: -27.3; 67.9) for the primary vaccination and from 95.6% (95%CI: 88.0; 98.4) to 67.7% (95%CI: 45.9; 80.8) for the first booster. Similar trends were observed for 65-79-years. The second booster VE against hospitalisation ranged between 82.0% (95%CI: 75.9; 87.0) and 83.9% (95%CI: 77.7; 88.4) for the ≥80-years and between 39.3% (95%CI: -3.9; 64.5) and 80.6% (95%CI: 67.2; 88.5) for 65-79-years. The first booster VE against COVID-19-related death declined over time for both age groups, while the second booster VE against death remained above 80% for the ≥80-years. Conclusions: Successive vaccine boosters played a relevant role in maintaining protection against COVID-19 hospitalisation and death, in the context of decreasing VE over time. Multi-country data from EHR facilitate robust near-real-time monitoring of VE in the EU/EEA and supports public health decision-making.

Background: In 2021–22, influenza A viruses dominated in Europe. The I-MOVE primary care network conducted a multicentre test-negative study to measure influenza vaccine effectiveness (VE). Methods: Primary care practitioners collected information on patients presenting with acute respiratory infection. Cases were influenza A(H3N2) or A(H1N1)pdm09 RT-PCR positive and controls were influenza virus negative. We calculated VE using logistic regression, adjusting for study site, age, sex, onset date, and presence of chronic conditions. Results: Between week 40 2021 and week 20 2022, we included over 11,000 patients of whom 253 and 1595 were positive for influenza A(H1N1)pdm09 and A(H3N2), respectively. Overall VE against influenza A(H1N1)pdm09 was 75% (95%CI: 43–89) and 81% (95%CI: 44–93) among those aged 15–64 years. Overall VE against influenza A(H3N2) was 29% (95%CI: 12–42) and 25% (95%CI: -41–61), 33% (95%CI: 14–49) and 26% (95% CI: -22 to 55) among those aged 0–14, 15–64 and over 65 years, respectively. The A(H3N2) VE among the influenza vaccination target group was 20% (95%CI: -6–39). All 53 sequenced A(H1N1)pdm09 viruses belonged to clade 6B.1A.5a.1. Among 410 sequenced influenza A(H3N2) viruses, all but 8 belonged to clade 3C.2a1b.2a.2. Discussion: Despite antigenic mismatch between vaccine and circulating strains for influenza A(H3N2) and A(H1N1)pdm09, 2021–22 VE estimates against circulating influenza A(H1N1)pdm09 were the highest within the I-MOVE network since the 2009 influenza pandemic. VE against A(H3N2) was lower than A(H1N1)pdm09, but at least one in five individuals vaccinated against influenza were protected against presentation to primary care with laboratory-confirmed influenza.