HIV VACCINE DEVELOPMENT AND EVALUATION - REALISTIC EXPECTATIONS

As of January 1998, more than 85 vaccines for 24 clinical indications are currently licensed in the United States. From the time of discover y of the etiologic agent to the development of a licensed vaccine, man y years have usually been required. Although many vaccines have been l icensed on the basis of one efficacy trial, multiple vaccine concepts and multiple efficacy trials (both in the United States and internatio nally) have at times been necessary. Over a relatively short period of time, there has been remarkable progress in human immunodeficiency vi rus (HIV) vaccine development, with over 34 different HIV candidate va ccines having been tested in phase 1 trials, and three having been tes ted in phase 2 trials. In spite of our incomplete understanding of HIV pathogenesis and correlates of protection, the first phase 3 efficacy trial has been initiated in the U.S. and tentative plans have been an nounced for three other phase 3 efficacy trials with the most advanced HIV candidate vaccines to begin in the next 3 years. Like many previo us vaccine development efforts, these initial HIV vaccine efficacy tri als could be the first of many large-scale efficacy trials in the futu re, testing various vaccine design concepts among different high-risk populations in both developed and developing countries, The choice of when and how to proceed to phase 3 trials remains a complex decision, but it is likely that only through such trials will further knowledge be gained to advance this important effort and reach our goal of a saf e and effective HIV vaccine.