Percorrer por autor "Hansen, Christian Holm"
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- Comparison of two methods for the estimation of COVID-19 vaccine effectiveness of the autumnal booster within the VEBIS-EHR network in 2022/23Publication . Monge, Susana; Humphreys, James; Nicolay, Nathalie; Braeye, Toon; Van Evercooren, Izaak; Hansen, Christian Holm; Emborg, Hanne-Dorthe; Fabiani, Massimo; Sacco, Chiara; Castilla, Jesús; Martínez-Baz, Iván; de Gier, Brechje; Hahné, Susan; Hinta Meijerink; Kristoffersen, Anja Bråthen; Machado, Ausenda; Soares, Patricia; Fontán-Vela, Mario; Nardone, Anthony; Kissling, Esther; Nunes, Baltazar; VEBIS-Lot 4 working groupWithin an infrastructure to monitor vaccine effectiveness (VE) against hospitalization due to COVID-19 and COVID-19 related deaths from November 2022 to July 2023 in seven countries in real-world conditions (VEBIS network), we compared two approaches: (a) estimating VE of the first, second or third COVID-19 booster doses administered during the autumn of 2022, and (b) estimating VE of the autumn vaccination dose regardless of the number of prior doses (autumnal booster approach). Retrospective cohorts were constructed using Electronic Health Records at each participating site. Cox regressions with time-changing vaccination status were fit and site-specific estimates were combined using random-effects meta-analysis. VE estimates with both approaches were mostly similar, particularly shortly after the start of the vaccination campaign, and showed a similar timing of VE waning. However, autumnal booster estimates were more precise and showed a clearer trend, particularly compared to third booster estimates, as calendar time increased after the vaccination campaign and during periods of lower SARS-CoV-2 activity. Moreover, the decrease in protection by increasing calendar time was more clear and precise than when comparing protection by number of doses. Therefore, estimating VE under an autumnal booster framework emerges as a preferred method for future monitoring of COVID-19 vaccination campaigns.
- COVID-19 vaccine effectiveness in the paediatric population aged 5-17 years: a multicentre cohort study using electronic health registries in six European countries, 2021 to 2022Publication . Soares, Patricia; Machado, Ausenda; Nicolay, Nathalie; Monge, Susana; Sacco, Chiara; Hansen, Christian Holm; Meijerink, Hinta; Martínez-Baz, Iván; Schmitz, Susanne; Humphreys, James; Fabiani, Massimo; Echeverria, Aitziber; AlKerwi, Ala'a; Nardone, Anthony; Mateo-Urdiales, Alberto; Castilla, Jesús; Kissling, Esther; Nunes, Baltazar; VEBIS-Lot 4 working groupBackground: During the first year of the COVID-19 pandemic, vaccination programmes targeted children and adolescents to prevent severe outcomes of SARS-CoV-2 infection. Aim: To estimate COVID-19 vaccine effectiveness (VE) against hospitalisation due to COVID-19 in the paediatric population, among those with and without previously documented SARS-CoV-2 infection. Methods: We established a fixed cohort followed for 12 months in Denmark, Norway, Italy, Luxembourg, Navarre (Spain) and Portugal using routine electronic health registries. The study commenced with paediatric COVID-19 vaccination campaign at each site between June 2021 and January 2022. The outcome was hospitalisation with a laboratory-confirmed SARS-CoV-2 infection or COVID-19 as the main diagnosis. Using Cox proportional hazard models, VE was estimated as 1 minus the confounder-adjusted hazard ratio of COVID-19 hospitalisation between vaccinated and unvaccinated. A random-effects meta-analysis was used to pool VE estimates. Results: We included 4,144,667 5-11-year-olds and 3,861,841 12-17-year-olds. In 12-17-year-olds without previous infection, overall VE was 69% (95% CI: 40 to 84). VE declined with time since vaccination from 77% ≤ 3 months to 48% 180-365 days after immunisation. VE was 94% (95% CI: 90 to 96), 56% (95% CI: 3 to 80) and 41% (95% CI: -14 to 69) in the Delta, Omicron BA.1/BA.2 and BA.4/BA.5 periods, respectively. In 12-17-year-olds with previous infection, one dose VE was 80% (95% CI: 18 to 95). VE estimates were similar for 5-11-year-olds but with lower precision. Conclusion: Vaccines recommended for 5-17-year-olds provided protection against COVID-19 hospitalisation, regardless of a previously documented infection of SARS-CoV-2, with high levels of protection in the first 3 months of the vaccination.
- Effectiveness of JN.1 monovalent COVID-19 vaccination in EU/EEA countries between October 2024 and January 2025: a VEBIS electronic health record network studyPublication . Humphreys, James; Blake, Alexandre; Nicolay, Nathalie; Braeye, Toon; Van Evercooren, Izaak; Hansen, Christian Holm; Moustsen-Helms, Ida Rask; Sacco, Chiara; Mateo-Urdiales, Alberto; Castilla, Jesús; Martínez-Baz, Iván; Machado, Ausenda; Brito, André; Ljung, Rickard; Pihlstrom, Nicklas; Mansiaux, Yohann; Monge, Susana; Bacci, Sabrina; Nunes, Baltazar; VEBIS-Lot 4 working groupWe estimated vaccine effectiveness (VE) of Omicron JN.1-adapted COVID-19 vaccines administered during the 2024 autumnal vaccination campaign against COVID-19 hospitalisation and death among eligible individuals aged ≥65 years. The study period was October 2024-January 2025. Using a common protocol across six EU/EEA study sites, we linked electronic health records to construct retrospective cohorts and applied Cox modelling to estimate VE via confounder-adjusted hazard ratios. The majority of vaccines administered during the study period were Omicron JN.1-adapted COVID-19 vaccines (99 %). VE against hospitalisation was 60 % (95 % Confidence Interval: 48-70 %) and against COVID-19-related death was 78 % (95 %CI: 64-87 %) among individuals aged 65-79 years; 58 % (95 %CI: 48-66 %) and 62 % (95 %CI: 32-79 %) among those aged ≥80 years. These results indicate high effectiveness in the initial months of the campaign. Continued monitoring is necessary to confirm these results, including estimates of VE in those with longer time since vaccination and during different variant predominance periods.
- Effectiveness of the 2023 Autumn XBB.1.5 COVID-19 Booster During Summer 2024 in the EU/EEA: A VEBIS Electronic Health Record Network StudyPublication . Humphreys, James; Nicolay, Nathalie; Braeye, Toon; Van Evercooren, Izaak; Hansen, Christian Holm; Moustsen-Helms, Ida Rask; Sacco, Chiara; Fabiani, Massimo; Castilla, Jesús; Martinez-Baz, Ivan; Machado, Ausenda; Soares, Patricia; Ljung, Rickard; Pihlstrom, Nicklas; Kissling, Esther; Nardone, Anthony; Monge, Susana; Bacci, Sabrina; Nunes, Baltazar; VEBIS-EHR Working GroupBackground: After a period of low SARS- CoV-2 activity, viral circulation increased in Europe from May 2024, driven byimmune-evasive KP sublineages of the JN.1 variant. We estimated vaccine effectiveness (VE) of the XBB.1.5 dose administeredin autumn 2023 against COVID-19-related hospitalisations and deaths in individuals 65 years of age or older during this period. Methods: We conducted a multi-country cohort study across six EU nations in the VEBIS-EHR network using linked electronichealth records. VE against COVID-19-related hospitalisation and death during June–August 2024 was estimated using Cox re-gression in a two-stage analysis, adjusting for demographics, comorbidities and prior vaccination history. Results: Among individuals 65–79 and ≥ 80 years old, respectively, VE of the XBB.1.5 dose ≥ 6 months post administration was13% (95% CI: −12% to 33%) and 7% (95% CI: −7% to 19%) against hospitalisation and 39% (95% CI: −7% to 65%) and 3% (95% CI:−23% to 23%) against deaths. Conclusions: XBB.1.5 vaccination provided minimal residual protection against severe COVID-19 outcomes among adults aged≥ 65 years more than 6 months after vaccination, during the summer 2024 period of increased SARS- CoV-2 activity.
- Monitoring COVID‐19 vaccine effectiveness against COVID‐19 hospitalisation and death using electronic health registries in ≥65 years old population in six European countries, October 2021 to November 2022Publication . Kislaya, Irina; Sentís, Alexis; Starrfelt, Jostein; Nunes, Baltazar; Martínez‐Baz, Iván; Nielsen, Katrine Finderup; AlKerwi, Ala'a; Braeye, Toon; Fontán‐Vela, Mario; Bacci, Sabrina; Meijerink, Hinta; Castilla, Jesús; Emborg, Hanne‐Dorthe; Hansen, Christian Holm; Schmitz, Susanne; Van Evercooren, Izaak; Valenciano, Marta; Nardone, Anthony; Nicolay, Nathalie; Monge, Susana; VEBIS‐Lot4 working groupBackground: 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, VE was estimated monthly over 8-week follow-up periods, allowing 1 month-lag for data consolidation. Cox proportional-hazards models were used to estimate adjusted hazard ratios (aHR) and VE = (1 - aHR) × 100%. Site-specific estimates were pooled using random-effects meta-analysis. Results: For ≥80 years, considering unvaccinated as the reference, 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. Multicountry data from EHR facilitate robust near-real-time VE monitoring in the EU/EEA and support public health decision-making.