Tweet
Pharmacoepidemiol Drug Saf
. 2025 Nov;34(11):e70239.
doi: 10.1002/pds.70239. Impact and Effectiveness of COVID-19 mRNA Vaccination Against COVID-19 Hospitalisation in Paediatrics: A Cohort Study Using Two Linked Data Sources in Spain
Belén Castillo-Cano 1 2 , Fabio Riefolo 2 3 , Felipe Villalobos 2 4 , Mar Martín-Pérez 1 2 , Davide Messina 5 , Roel Elbers 6 , Dorieke Brink-Kwakkel 6 , Carlo Alberto Bissacco 4 , Elena Segundo 4 , Luis Carlos Saiz 7 8 , Leire Leache 7 8 , Elisa Barbieri 2 9 , Tiago Vaz 6 , Rosa Gini 2 5 , Olaf Klungel 10 , Elisa Martín-Merino 1 2
Affiliations
Purpose: Despite Spain's > 2 million COVID-19 paediatric cases before 2024, few required hospitalisations (8900). We aimed to estimate the effectiveness of two-dose COVID-19 vaccinations against hospitalisation 'with' and 'for' COVID-19 in paediatrics.
Methods: All individuals aged 5-14 years between January 2021 and February 2022 in two databases in Spain (SIDIAP and BIFAP) vaccinated against COVID-19 (two doses) were matched 1:1 to unvaccinated controls with the same age, sex, region and comorbidities on the dates of vaccination. Individuals with previous SARS-CoV-2 infections were excluded. COVID-19 was identified as the main reason (hospitalisation 'for' COVID-19; SIDIAP) or as one of the reasons (hospitalisation 'with' COVID-19; BIFAP) for hospitalisation with a positive SARS-CoV-2 test ±30 days. Incidence rate differences and vaccine effectiveness (VE; 95% CI; controlled by inverse probability weights) against hospitalisations 'for' and 'with' COVID-19 were calculated.
Results: The cohorts included 75 361 (SIDIAP) and 178 589 (BIFAP) pairs. Among vaccinated individuals (99.99% with mRNA vaccines) and controls, < 5 and 15 hospitalisations 'for' COVID-19 were identified (SIDIAP), whereas 21 and 32 hospitalisations 'with' COVID-19 (BIFAP), all aged 12-14 years old. Vaccination prevented 2.5 hospitalisations 'for' and 0.5 'with' COVID-19 during the Delta period, and 0.8 hospitalisations 'with' COVID-19 during Omicron predominance per 106 person-days. The VE was 94% (95% CI: 52%-99%; SIDIAP) and 53% (95% CI: 18%-74%; BIFAP).
Conclusions: Given the low incidence of hospitalised COVID-19, two-dose series mRNA vaccination showed moderate-high effectiveness with few averted cases. Including hospitalisation 'with' COVID-19 underestimated the effectiveness. If paediatric severe COVID-19 remains rare, larger databases are required to understand precisely the effectiveness and impact of new vaccines.
Trial registration: EU PAS Register number: EUPAS47725.
Keywords: COVID‐19 vaccine effectiveness; children and adolescents; hospital COVID‐19 records; paediatrics; real‐word data; retrospective cohort study.
. 2025 Nov;34(11):e70239.
doi: 10.1002/pds.70239. Impact and Effectiveness of COVID-19 mRNA Vaccination Against COVID-19 Hospitalisation in Paediatrics: A Cohort Study Using Two Linked Data Sources in Spain
Belén Castillo-Cano 1 2 , Fabio Riefolo 2 3 , Felipe Villalobos 2 4 , Mar Martín-Pérez 1 2 , Davide Messina 5 , Roel Elbers 6 , Dorieke Brink-Kwakkel 6 , Carlo Alberto Bissacco 4 , Elena Segundo 4 , Luis Carlos Saiz 7 8 , Leire Leache 7 8 , Elisa Barbieri 2 9 , Tiago Vaz 6 , Rosa Gini 2 5 , Olaf Klungel 10 , Elisa Martín-Merino 1 2
Affiliations
- PMID: 41125425
- DOI: 10.1002/pds.70239
Purpose: Despite Spain's > 2 million COVID-19 paediatric cases before 2024, few required hospitalisations (8900). We aimed to estimate the effectiveness of two-dose COVID-19 vaccinations against hospitalisation 'with' and 'for' COVID-19 in paediatrics.
Methods: All individuals aged 5-14 years between January 2021 and February 2022 in two databases in Spain (SIDIAP and BIFAP) vaccinated against COVID-19 (two doses) were matched 1:1 to unvaccinated controls with the same age, sex, region and comorbidities on the dates of vaccination. Individuals with previous SARS-CoV-2 infections were excluded. COVID-19 was identified as the main reason (hospitalisation 'for' COVID-19; SIDIAP) or as one of the reasons (hospitalisation 'with' COVID-19; BIFAP) for hospitalisation with a positive SARS-CoV-2 test ±30 days. Incidence rate differences and vaccine effectiveness (VE; 95% CI; controlled by inverse probability weights) against hospitalisations 'for' and 'with' COVID-19 were calculated.
Results: The cohorts included 75 361 (SIDIAP) and 178 589 (BIFAP) pairs. Among vaccinated individuals (99.99% with mRNA vaccines) and controls, < 5 and 15 hospitalisations 'for' COVID-19 were identified (SIDIAP), whereas 21 and 32 hospitalisations 'with' COVID-19 (BIFAP), all aged 12-14 years old. Vaccination prevented 2.5 hospitalisations 'for' and 0.5 'with' COVID-19 during the Delta period, and 0.8 hospitalisations 'with' COVID-19 during Omicron predominance per 106 person-days. The VE was 94% (95% CI: 52%-99%; SIDIAP) and 53% (95% CI: 18%-74%; BIFAP).
Conclusions: Given the low incidence of hospitalised COVID-19, two-dose series mRNA vaccination showed moderate-high effectiveness with few averted cases. Including hospitalisation 'with' COVID-19 underestimated the effectiveness. If paediatric severe COVID-19 remains rare, larger databases are required to understand precisely the effectiveness and impact of new vaccines.
Trial registration: EU PAS Register number: EUPAS47725.
Keywords: COVID‐19 vaccine effectiveness; children and adolescents; hospital COVID‐19 records; paediatrics; real‐word data; retrospective cohort study.