Influenza Immunization in Low- and Middle-Income Countries: Preparing for Next-Generation Influenza Vaccines.

Influenza vaccines have a long history of safety and demonstrated efficacy; however, they are seldom used in low- and middle-income countries (LMICs). Although reasons for underuse are multifactorial and differ from country to country, the need for up to twice-annual reformulation and yearly vaccination are obstacles to influenza prevention in LMICs. Major efforts are underway to produce next-generation influenza vaccines that provide durable protection against drifted strains, and such vaccines could address these unmet needs. However, additional information is required to influence immunization policies in most LMICs. Better estimates of vaccine impact on important public health outcomes, more affordable vaccines, improved programmatic suitability, and strengthened immunization delivery infrastructures are needed and must be considered early during the development of new vaccines if widespread adoption in LMICs is to be achieved.