Immunization in Low- and Middle-Income Countries

Immunization prevented an estimated 37 million deaths in low- and middle-income countries (LMICs) from 2000 through 2019. Support from Gavi, the Vaccine Alliance, has catalyzed the introduction of new and underused vaccines in low- and lower middle-income countries. With the addition of vaccines targeted to preadolescents and adolescents, pregnant women and the elderly, as well as additional doses of existing vaccines in the second year of life or later, immunization programs have evolved from primarily targeting infants to targeting individuals across the life course. In 2019, 85% of infants worldwide (116 million) were vaccinated with third dose of diphtheria-tetanus-pertussis vaccine (DTP3). Among the 20 million infants not vaccinated with DTP3, approximately 14 million (70%) did not receive DTP1 (zero-dose children), representing lack of access to vaccination services and likely other health services. Only two countries, Pakistan and Afghanistan, continue to have endemic wild-type poliovirus transmission in 2021, but immunity gaps to type 2 polio virus caused by global inactivated polio vaccine (IPV) shortages and delays in IPV introduction have led to type 2 vaccine-derived poliovirus (cVDPV2) outbreaks. All six WHO regions have established measles elimination goals and five out of six have rubella elimination goals, but measles cases surged reaching a peak in 2019, the largest number of reported cases since 1996. The Immunization Agenda 2030: A Global Strategy to Leave No One Behind (IA2030), was endorsed by all WHO member states through the World Health Assembly (WHA) in August 2020. To realize the vision of the Immunization Agenda 2030, especially in low- and lower middle-income countries, several challenges need to be overcome regarding country ownership and management, financing, human resources, sustainable global supply of vaccines at affordable prices, immunization supply chains, information systems, community demand, and service delivery, including in fragile settings such as with outbreaks, conflicts, and humanitarian emergencies. The COVID-19 pandemic led to disruption of services but also opportunities with the ambitious effort to provide COVID-19 vaccines through the COVAX Global Vaccine Facility. Looking to the future, research and innovation will play a key role to help achieve IA2030 goals and immunization programs will need to catalyze the move towards integration and life course vaccination.