Measuring the impact of COVID-19 vaccination and immunity waning: a modelling study for Portugal
          Caetano, Constantino P.; Morgado, M. Luísa; et al  
          
          Vaccine,  (2022), 7115-7121  
          https://www.sciencedirect.com/science/article/pii/S0264410X22012555?via%3Dihub  
           
            
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