Combination Vaccines: Moving Beyond Typhoid.

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 disease, and even less among children aged <5 years. Invasive nontyphoidal disease is the dominant clinical presentation of 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 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 vaccine is attractive for Africa, and a bivalent enteric fever vaccine for Asia, a quadrivalent vaccine covering the 4 main disease-causing serovars of would provide a single vaccine option for global coverage.