<i>Salmonella</i> Combination Vaccines: Moving Beyond Typhoid

Abstract

There is now a robust pipeline of licensed and World Health Organization (WHO)-prequalified typhoid conjugate vaccines with a steady progression of national introductions. However, typhoid fever is responsible for less than half the total global burden of <i>Salmonella</i> disease, and even less among children aged <5 years. Invasive nontyphoidal <i>Salmonella</i> disease is the dominant clinical presentation of <i>Salmonella</i> in Africa, and over a quarter of enteric fever in Asia is due to paratyphoid A. In this article, we explore the case for combination <i>Salmonella</i> vaccines, review the current pipeline of these vaccines, and discuss key considerations for their development, including geographies of use, age of administration, and pathways to licensure. While a trivalent typhoid/nontyphoidal <i>Salmonella</i> vaccine is attractive for Africa, and a bivalent enteric fever vaccine for Asia, a quadrivalent vaccine covering the 4 main disease-causing serovars of <i>Salmonella enterica</i> would provide a single vaccine option for global <i>Salmonella</i> coverage.