Immunization

Immunization is one of the most cost-effective public health interventions, averting an estimated 4.4 million deaths yearly^[1]

In 2024, global coverage of the third dose of diphtheria-tetanus-pertussis (DTP3) vaccine – often used as a marker of how well countries are providing routine immunization services to children – stood at 85 per cent, as per the latest WHO and UNICEF estimates of national immunization coverage (WUENIC).

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Despite ongoing efforts towards recovery and strengthening beyond pre-pandemic (2019) levels, a staggering 20 million children remained either unvaccinated or under-vaccinated in 2024. Furthermore, the number of children who did not receive any vaccines, often referred to as zero-dose children, reached 14.3 million – an increase from 12.9 million in 2019. 

Measles, because of its high transmissibility, acts as a ‘canary in the coalmine’, quickly exposing immunity gaps in the population. The coverage of measles-containing vaccine (MCV) is thus often used as a tracer for protection. In 2024, coverage of the first dose of measles-containing-vaccine (MCV1) increased to 84 per cent, with 20.6 million children not receiving the potentially life-saving vaccine. These figures fall short of the 95 per cent coverage needed to prevent outbreaks, reduce deaths, and achieve elimination goals. 

Access to life-saving vaccines to combat diseases is not universal and varies across regions and countries 

The first dose of the diphtheria-tetanus-pertussis vaccine (DTP1) – a proxy indicator for access to immunization services – ranged from 48 percent in Sudan to 99 percent in 39 countries, including 11 non-programme countries and 9 countries in East Asia and the Pacific. Twenty-seven countries had DTP1 coverage below 80 percent, suggesting the need to enhance access to immunization services in these locations. Most of these countries were in West and Central Africa (n=7), Eastern and Southern Africa (n=6) and Latin America and the Caribbean (n=6).  

Globally, more than half (over 50 per cent) of zero-dose children are concentrated in just nine countries: Nigeria, India, Sudan, Democratic Republic of Congo, Ethiopia, Indonesia, Yemen, Afghanistan and Angola. However, it is important to note that some populous countries contribute heavily to global figures, despite high rates of immunization coverage. For instance, in 2024, India accounted for 909,000 (6 per cent) zero-dose children, despite achieving 96 per cent coverage for a cohort of 22.7 million surviving infants. 

In recent years, there has been a significant emphasis on reducing the overall number of zero-dose children, and this focus has yielded positive results, particularly in terms of DTP1 coverage. It is crucial to maintain these efforts and build upon them. However, the latest data from WUENIC emphasizes the need to expand our approach by considering additional metrics that assess the risks and progress of immunization programmes, including vaccine coverage. This approach ensures that no child is left behind, as countries with larger infant populations often overshadow smaller cohort countries with extremely low vaccine coverage. 

111 countries achieved at least 90 per cent coverage of DTP3 vaccine

The percentage of children receiving DTP3 – often used to measure the overall system strength to deliver infant vaccination – has a global target of 90 per cent as set by the Immunization Agenda 2030. In 2024, 111 countries (57 per cent) had achieved at least 90 per cent coverage of DTP3.  This is fewer than in 2019, when 125 countries met the target. 

In 2024, Europe and Central Asia, and South Asia had the highest DTP3 coverage at 92 per cent, whilst West and Central Africa had the lowest coverage at 72 per cent. Europe and Central Asia and South Asia were the only two regions that had achieved at least 90 per cent coverage. 

Notably, South Asia saw DTP3 coverage increase from 90 per cent in 2023 to 92 per cent in 2024, driven by increased coverage in India from 91 per cent in 2023 to 94 per cent in 2024– the country with the largest infant population in the region. West and Central Africa also saw a slight increase in coverage, from 71 per cent in 2022 to 72 per cent in 2023. On the other hand, DTP3 coverage in Middle East and North Africa declined from 81 per cent in 2023 to 79 per cent in 2024, and coverage in Europe and Central Asia fell from 94 per cent in 2023 to 92 percent in 2024. 

Challenges to increasing vaccination coverage are numerous and persist in fragile states and those affected by conflict

Several factors contribute to the disruption of health systems and hinder the sustainable delivery of vaccination services. These factors include conflict, inadequate investment in national immunization programs, shortages of vaccines as well as disease outbreaks. Among the children who remain unvaccinated or under-vaccinated, approximately 10.2 million infants (51 per cent) live in countries with institutional and social fragility or countries affected by conflict.^[2] Children residing in such challenging circumstances are the most vulnerable to disease outbreaks and require urgent attention and support.

In 2024, there were eight countries with DTP3 coverage of 60 per cent or less (Afghanistan, Azerbaijan, Bolivia, Central African Republic, Lebanon, Papua New Guinea, Sudan and Yemen). Six out of eight of these countries have institutional and social fragility or are affected by conflict.^[3]

To elevate global immunization levels, it is essential to prioritize efforts in countries with the highest absolute numbers of unvaccinated children. However, it’s equally important to ensure that countries with low coverage rates, where children are most likely to miss out on immunization, receive the attention they need, particularly in countries with smaller birth cohorts. 

Pneumococcal and rotavirus vaccine coverage continues to expand, particularly in lower middle income countries

Thanks to the collaborative efforts of UNICEF, its partners and countries, vaccines are now safer and more accessible than ever before. The cost of fully immunizing a child in low-income countries has decreased from over US $24 in 2013 to just US $18 per child.^[4]

Despite various challenges, countries have made progress in vaccine introductions. As of 2024, 160 countries (two more than in 2023) included the pneumococcal conjugate vaccine in their immunization programmes, providing protection against pneumonia. Additionally, 127 (three more than in 2023) countries have incorporated the rotavirus vaccine, which helps prevent diarrhoea. 

Immunization throughout the life-course provides significant societal, economic and productivity benefits, highlighting its importance as an essential intervention that should be prioritized by governments and policy makers

Human papillomavirus (HPV) is a common viral infection that can lead to cervical cancer in women. By the end of 2024, the HPV vaccine had been introduced in 147 countries. However, only 31 per cent of girls received the first dose of HPV vaccine, and 28 per cent received the last dose, indicating the need for increased efforts in this area.

Preventing child deaths from preventable causes and ensuring children’s optimal health and well-being is a priority. The cost of a vaccine, often less than US $1, is significantly lower than the expenses associated with treating a sick child or combating disease outbreaks. Investing US $1 in childhood vaccination can potentially yield a return on investment of US $20 in low- and middle-income countries, demonstrating high returns on investment from immunization programmes.^[5]

For more information about the cost and financing of vaccination, you can find additional details here.

In summary, although significant strides have been made in global immunization efforts, we are still not reaching every child with life-saving vaccines. The rise in zero-dose children since the pre-pandemic period, and disparities in access to immunization services underscore the need for targeted interventions in fragile and conflict-affected regions. Despite these obstacles, the introduction of vaccines such as pneumococcal conjugate and rotavirus vaccines showcases potential for substantial improvements. To fully realize the societal, economic, and health benefits of immunization, sustained investment and innovative strategies are essential, especially in countries with the highest numbers of unvaccinated children and countries with the lowest vaccine coverage.

[1] Carter, Austin and Msemburi, William and Sim, So Yoon and A.M. Gaythorpe, Katy and Lindstrand, Ann and Hutubessy, Raymond C.W., Modeling the Impact of Vaccination for the Immunization Agenda 2030: Deaths Averted Due to Vaccination Against 14 Pathogens in 194 Countries from 2021-2030 (April 20, 2021). Available at SSRN: https://ssrn.com/abstract=3830781 or http://dx.doi.org/10.2139/ssrn.3830781

[2] World Bank Fragile and Conflict-affected Situations (FCS), FY25, 1 July 2024: https://www.worldbank.org/en/topic/fragilityconflictviolence/brief/harmonized-list-of-fragile-situations

[3] World Bank Fragile and Conflict-affected Situations (FCS), FY25, 1 July 2024: https://www.worldbank.org/en/topic/fragilityconflictviolence/brief/harmonized-list-of-fragile-situations

[4] Centers for Disease Control and Prevention (CDC), Fast Facts on Global Immunization. https://www.cdc.gov/global-immunization/fast-facts/index.html, Updated: 16 May, 2024.

[5] S.Y. Sim, E. Watts, D. Constenla, L. Brenzel, B.N. Patenaude, Return On Investment From Immunization Against 10 Pathogens In 94 Low- And Middle-Income Countries, 2011–30, 2020.

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