Clinical evaluation of new pneumococcal vaccines: the Finnish approach.

Clinical evaluation of a new vaccine should be based on information about the epidemiology and pathogenesis of the infection to be prevented, the protective immunity to this infection, and the immunological properties of the vaccine to be evaluated. In this review we describe one approach to evaluate a new vaccine, using our experience with pneumococcal conjugates as an example. Information on the epidemiology, pathogenesis and host responses was collected mainly during 1987-1992, improvement in diagnostic methods was carried out during 1990-1995, and the immunogenicity of vaccine candidates was tested during 1992-1995. Based on these factors, a randomized, controlled, blinded efficacy trial of two pneumococcal conjugate vaccines against acute otitis media was started in Finland in 1995. Enrolment of 2,497 infants has now been completed by April 1997, and the follow-up phase will continue until 1999.