A study using data from over 20 million participants in Norway shows that COVID-19 vaccines effectively prevent long COVID symptoms. Meta-analytic subdistribution hazard ratios (SHRs) ranged from 0.48 to 0.71 across different datasets. Vaccination also reduced the risk of post-acute complications such as heart failure, venous thromboembolism, and arterial thrombosis. The study used federated analytics across three European countries, including Norway, using the Observational Medical Outcomes Partnership (OMOP) common data model. In Norway, data from six registries covering 5.4 million people were mapped to the OMOP CDM. The study included 2.36 million vaccinated and 1.53 million unvaccinated individuals. Vaccination reduced the risk of long COVID symptoms in all cohorts, with SHRs ranging from 0.55 to 0.64. Post-acute complications were also reduced, with the exception of certain groups. The study highlights the real-world effectiveness of vaccines in preventing long COVID and post-COVID complications, consistent with findings from other countries. The use of federated analytics across national borders to analyze linked real-world data mapped to the OMOP CDM is demonstrated. The study confirms the generalizability and reproducibility of recent publications. Funding and potential conflicts of interest are noted. The study was conducted by researchers from the University of Oslo, the University of Oxford, and the Erasmus Medical Center. The findings support the effectiveness of COVID-19 vaccines in preventing long-term symptoms and complications.A study using data from over 20 million participants in Norway shows that COVID-19 vaccines effectively prevent long COVID symptoms. Meta-analytic subdistribution hazard ratios (SHRs) ranged from 0.48 to 0.71 across different datasets. Vaccination also reduced the risk of post-acute complications such as heart failure, venous thromboembolism, and arterial thrombosis. The study used federated analytics across three European countries, including Norway, using the Observational Medical Outcomes Partnership (OMOP) common data model. In Norway, data from six registries covering 5.4 million people were mapped to the OMOP CDM. The study included 2.36 million vaccinated and 1.53 million unvaccinated individuals. Vaccination reduced the risk of long COVID symptoms in all cohorts, with SHRs ranging from 0.55 to 0.64. Post-acute complications were also reduced, with the exception of certain groups. The study highlights the real-world effectiveness of vaccines in preventing long COVID and post-COVID complications, consistent with findings from other countries. The use of federated analytics across national borders to analyze linked real-world data mapped to the OMOP CDM is demonstrated. The study confirms the generalizability and reproducibility of recent publications. Funding and potential conflicts of interest are noted. The study was conducted by researchers from the University of Oslo, the University of Oxford, and the Erasmus Medical Center. The findings support the effectiveness of COVID-19 vaccines in preventing long-term symptoms and complications.