One Missed Dose, Millions at Risk: The Hidden Crisis in Global Immunisation

Global childhood immunisation improved slightly in 2025, but the gains conceal a deeper vulnerability: millions of children remain entirely unvaccinated, while millions more begin their vaccine schedules without completing them. As measles outbreaks spread and coverage remains below pre-pandemic levels, the central challenge is no longer simply getting vaccines into countries, it is building health systems capable of reaching every child repeatedly and reliably.

According to the World Health Organization (WHO) and UNICEF, 90 per cent of infants worldwide, nearly 116 million children, received at least one dose of the vaccine against diphtheria, tetanus and pertussis in 2025. About 110 million infants, equivalent to 85 per cent of the global total, completed all three recommended doses.

Both figures increased by one percentage point from the previous year. Yet global coverage remained below its 2019 level, showing that the recovery from pandemic-era disruption is still incomplete. The gap is crucial because vaccination coverage does not recover simply when global percentages begin to rise. It recovers when protection becomes consistent across countries, districts and communities. A relatively strong global average can coexist with deep pockets of exclusion where outbreaks remain likely.

WHO and UNICEF estimate that 13.5 million children received no vaccine during their first year of life in 2025. The figure was around 750,000 lower than in 2024, but it still represents millions of children with little or no protection against preventable disease. The data also exposes a second problem that is less visible than the zero-dose crisis. More than 7.3 million infants received their first DTP vaccine but missed their first measles dose. These children were not entirely beyond the reach of health services. They entered the system but did not remain connected to it.

Measles Is Exposing the Weakest Links

Measles coverage offers the clearest warning that modest progress in overall immunisation has not restored population-level protection. WHO and UNICEF reported that 84 per cent of children received a first measles vaccine dose in 2025, while only 77 per cent received the second. Both rates remained far below the 95 per cent threshold needed to prevent widespread transmission.

During the same year, 57 countries reported major or disruptive measles outbreaks. The outbreak figures show why global averages can be misleading. Measles spreads rapidly when immunity falls in particular communities, even when national or international coverage appears relatively high. Small geographic gaps can become major public-health vulnerabilities.

The decline between the first and second measles doses is especially significant. It suggests that the problem is not limited to vaccine supply. Families may struggle to return to health facilities because of distance, transport costs, displacement or insecurity. Clinics may lack workers, reliable records or the capacity to follow up with children who miss appointments.

The difference between starting and completing vaccination thus reveals the strength of the wider health system. Where services are fragmented, children may receive one dose during a campaign but miss the protection that depends on continued care.

Vaccination programmes depend on public confidence as much as clinical availability. When misinformation grows or health institutions lose credibility, even countries with strong infrastructure can experience declining coverage.

Conflict Explains the Crisis, but Not All of It

More than half of the world's zero-dose children live in fragile or conflict-affected countries, according to the report. In these settings, vaccination programmes must operate amid insecurity, political instability and scarce resources. Conflict can interrupt vaccine supply chains, close health facilities, displace workers and make entire communities inaccessible. Children are often missed not because vaccines do not exist, but because the systems required to deliver them have weakened or collapsed.

The contrasting experiences of Syria and Sudan show that outcomes can shift quickly. Syria experienced sharp declines in vaccination coverage during 2025, while Sudan recorded one of the world's largest improvements after access to health services expanded despite continuing conflict. It suggests that instability does not make progress impossible, but it makes progress highly dependent on access. Even in conflict settings, vaccination coverage can improve when health workers and services reach previously excluded communities. The reverse is also true: gains can disappear rapidly when insecurity cuts off access.

Yet the latest figures also show that immunisation weakness is not confined to fragile states. WHO and UNICEF reported declining vaccination rates in several middle- and high-income countries, linking the trend to weakening political commitment, structural barriers and vaccine hesitancy.

South Africa's DTP coverage has fallen significantly since 2019, while Bosnia and Herzegovina recorded a sharp drop in measles vaccination during the past year.

These examples broaden the meaning of the global vaccination crisis. In poorer or conflict-affected countries, children may be excluded because health services cannot reach them. In wealthier settings, vaccines may be physically available but weakened trust, unequal access or declining political attention may prevent their use.

The Next Battle Is Completion, Not First Contact

WHO, UNICEF and Gavi, the Vaccine Alliance, are urging governments to strengthen immunisation services in fragile settings, counter false health information, increase financial support and improve disease surveillance and vaccination data.

The next phase of the global immunisation effort will need to move beyond a narrow focus on first doses. The critical measure will be whether health systems can keep children connected until they complete every recommended dose. It will require more accurate local data, because national averages can hide districts where coverage has collapsed. It will also require stronger surveillance, allowing authorities to identify immunity gaps before they turn into outbreaks.

Governments will need to invest in health workers, clinics, vaccine storage, transport and follow-up systems. Public communication will be equally important in countries where misinformation or distrust is contributing to falling uptake.

The 2025 figures offer evidence of progress, but not yet of a secure recovery. More infants received DTP vaccines, and the number of zero-dose children declined. But measles coverage remains dangerously low, millions are dropping out between doses, and outbreaks are already exposing the consequences.

The global vaccination challenge is no longer defined only by whether vaccines are available, but by whether health systems can deliver them consistently, whether communities trust those systems, and whether governments sustain political and financial commitment after the immediate crisis has passed. Until those conditions are met, modest improvements in global coverage will remain vulnerable to reversal and millions of children will continue to face risks that modern medicine already knows how to prevent.