Federated causal inference based on real-world observational data sources: application to a SARS-CoV-2 vaccine effectiveness assessment. - Meurisse, Marjan; Estupiñán-Romero, Francisco; González-Galindo, Javier; Martínez-Lizaga, Natalia; Royo-Sierra, Santiago; Saldner, Simon; Dolanski-Aghamanoukjan, Lorenz; Degelsegger-Marquez, Alexander; Soiland-Reyes, Stian; Van Goethem, Nina; Bernal-Delgado, Enrique (BMC Medical Research Methodology, 2023)