THE INTRODUCTION OF ROUTINE HAEMOPHILUS-INFLUENZAE TYPE-B CONJUGATE VACCINE IN CHILE - A FRAMEWORK FOR EVALUATING NEW VACCINES IN NEWLY INDUSTRIALIZING COUNTRIES

Objective. To determine the burden of Haemophilus influenzae type b (H ib) disease, the safety and immunogenicity of Hib conjugate vaccine, t he practicality of combining Hib conjugate and diphtheria-tetanus-pert ussis vaccines and the effectiveness of routine vaccination. Study des igns. A series of studies were carried out involving infants and child ren in Santiago, Chile. The study designs included retrospective surve illance, cost-benefit analysis, randomized placebo-controlled trials o f safety and immunogenicity and a Phase IV postlicensure evaluation of vaccine effectiveness.Results. The studies included in this stepwise process showed that Hib invasive disease was a significant public heal th problem with a substantial economic burden; that combining Hib conj ugate and diphtheria-tetanus-pertussis vaccines was practical, safe an d elicited a strong immunologic response; and that the combined formul ation afforded a high level of protection against invasive Hib disease (90% effectiveness). Conclusions. In July, 1996, Chile became only th e third newly industrializing country to introduce routine Hib conjuga te vaccination. New vaccines, such as Hib conjugates, will be more exp ensive than existing ones. The stepwise process used in Chile may serv e as an example for the evaluation of new vaccines in nonindustrialize d countries.