(NewsNation) — Confidence that vaccines are important for children dropped after the start of the pandemic, including in the United States, where 79% of people profess confidence in the importance of vaccines.

UNICEF’s new State of the World’s Children report highlights what’s at risk when children aren’t immunized from preventable illnesses. Vaccine availability, accessibility and affordability are all challenges facing underserved communities, but the COVID-19 pandemic presented a new challenge: Vaccine confidence in several countries, including the U.S., has waned.

Altogether, the challenges of the past three years have chipped away at more than a decade of progress in routine childhood immunization, UNICEF Executive Director Catherine Russell said.

“While vaccine confidence is far from being the most important determinant of vaccine demand in most communities, the apparent rise in hesitancy cannot be ignored,” Russell wrote.

Between 2019 and 2021, 67 million children missed out entirely or partially on routine immunization, UNICEF estimated. The number who missed out entirely is 48 million.

That represents an overall 5% decline in the share of vaccinated children at a time when childhood immunization already was stagnating, according to the report.

The COVID-19 pandemic is partially responsible for a vaccine disruption that already has created setbacks.

The number of measles outbreaks in 2022, for example, doubled from the previous year. Poliovirus discoveries in places such as Israel, Northern Ireland and the U.S. also served as a “reminder that even remarkable progress … can be put at risk if we fail to vaccinate every child,” the report states.

“Failure to protect children against disease has serious consequences,” Russell wrote. “Put bluntly, children die, and many more suffer lifelong disabilities.”