Advance system testing: Vaccine benefit studies using multi-country electronic health data: the example of pertussis vaccination od Tin Tin Htar, M, De Ridder, M, Braeye, T, Correa, A, McGee, C, De Lusignan, S, Duarte-Salles, T, Huerta-Alvares, C, Martín-Merino, E, Tramontan, L, Danieli, G, Picelli, G, Van Der Maas, N, Berencsi, K, Arnheim-Dahlström, L, Heininger, U, Emborg, H, Weibel, D, Bollaerts, K, Sturkenboom, M