Effectiveness of the 23-valent pneumococcal polysaccharide vaccine against vaccine serotype pneumococcal pneumonia in adults: A case-control test-negative design study. oleh Hannah Lawrence, Harry Pick, Vadsala Baskaran, Priya Daniel, Chamira Rodrigo, Deborah Ashton, Rochelle C Edwards-Pritchard, Carmen Sheppard, Seyi D Eletu, David Litt, Norman K Fry, Samuel Rose, Caroline Trotter, Tricia M McKeever, Wei Shen Lim