An additional 2.7 million children remain un- or under-vaccinated in comparison to pre-pandemic levels, the United Nations has warned.

This stall in immunizations has created dangerous coverage gaps that enable outbreaks of diseases like measles, the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF) reported on Monday. 

The number of children without a single dose of the diphtheria, tetanus and pertussis (DTP) triple vaccination increased from 12.8 million before the pandemic began to 14.5 million last year, the report said.

The share of children receiving the triple shot stood at 84% in 2023, the same as the previous year, and down from the 86% recorded in 2019.

"The latest trends demonstrate that many countries continue to miss far too many children," UNICEF chief Catherine Russell said in a statement.

Why are childhood vaccinations declining?

More than half of the world's unvaccinated children live in 31 countries with fragile, conflict-affected settings. Children from unstable or violent countries are especially vulnerable to contracting preventable diseases, due to lacking access to security, nutrition and health services.

Children in these countries are also much less likely to receive follow-up shots that are necessary for full efficiency.

The number of children who did not receive even a single dose of the DTP vaccine rose to 14.5 million in 2023, up from 13.9 million in 2022 and 12.9 million in 2019.

Monday's report also found that 6.5 million children did not get their third DTP dose.

"We are off track," World Health Organization vaccine chief Kate O'Brien said. "Global immunization coverage has yet to fully recover from the historic backsliding that we saw during the course of the pandemic," she added.

O'Brien said that skepticism over vaccines in wealthier countries — which exploded during the COVID-19 pandemic — also impacts other regions, for example, when people with migration backgrounds based in Europe spread misinformation in their home countries.

Measles outbreaks on the rise

More than 300,000 measles cases were confirmed in 2023 — nearly three times as many as a year earlier, UNICEF Association Director of Immunization Ephrem Lemango said.

Around 103 countries with low vaccination coverage of 80% or lower have suffered measles outbreaks in the past five years. By contrast, 91 countries with strong measles vaccine coverage experienced no outbreaks.

"Alarmingly, nearly three in four infants live in places at the greatest risk of measles outbreaks," Lemango said, pointing out that 10 crisis-ridden countries, including Sudan, Yemen and Afghanistan, account for more than half of children not vaccinated against measles.

WHO chief Tedros Adhanom Ghebreyesus called measles outbreaks the "canary in the coal mine, exposing and exploiting gaps in immunization and hitting the most vulnerable first."

sp/ab (dpa, AFP, epd)