Reduction in hospital admissions for pneumonia in non-institutionalised elderly people as a result of influenza vaccination: a case-control study in Spain.

by Puig-Barberà, J, Márquez-Calderón, S, Masoliver-Fores, A, Lloria-Paes, F, Ortega-Dicha, A, Gil-Martín, M, Calero-Martínez, M J
Published 1997