PRIORIX (Measles, Mumps, and Rubella Vaccine, Live): A Comprehensive Clinical and Regulatory Monograph

Introduction and Regulatory Landscape

The landscape of measles, mumps, and rubella (MMR) prevention in the United States underwent a significant transformation in 2022 with the introduction of a second combination vaccine. For over four decades, a single product, M-M-R II, manufactured by Merck & Co., Inc., was the sole option available to clinicians. The approval of PRIORIX, a live attenuated trivalent vaccine manufactured by GlaxoSmithKline (GSK) Biologicals SA, marked the end of this long-standing monopoly and introduced a new dynamic to public health strategies for controlling these vaccine-preventable diseases.[1] This monograph provides a comprehensive clinical and regulatory analysis of PRIORIX, detailing its virological composition, summarizing the extensive clinical data on its immunogenicity and safety, and providing a direct comparison with the incumbent M-M-R II vaccine.

Overview of PRIORIX: A Global Vaccine with Recent US Approval

While new to the United States market, PRIORIX possesses a long and extensive history of use globally. It is not an experimental or novel biologic but rather a well-established vaccine with a substantial post-marketing record. Since its initial authorization in 1997, PRIORIX has been licensed in more than 100 countries, including all European nations, Canada, Australia, and New Zealand.[1] Over this period, more than 850 million doses have been distributed worldwide, creating a vast repository of real-world evidence on its effectiveness and safety.[3]