Fewer children around the world missed receiving routine vaccinations in 2022 compared to the year before, indicating a rebound in childhood immunizations following the COVID-19 pandemic, according to new statistics released by the World Health Organization and UNICEF.

Last year, 20.5 million children did not get one or more rounds of the DTaP (diphtheria, tetanus and pertussis) vaccine, which is used as a global marker for immunization coverage, according to a joint statement released Tuesday by WHO and UNICEF. That's compared to the 24.4 million children who missed out on one ore more rounds of that vaccinate in 2021.

"These data are encouraging, and a tribute to those who have worked so hard to restore life-saving immunization services after two years of sustained decline in immunization coverage," Dr. Tedros Adhanom Ghebreyesus, WHO director-general, said in the statement. "But global and regional averages don't tell the whole story and mask severe and persistent inequities. When countries and regions lag, children pay the price."

The organizations note that the current numbers remain higher than the 18.4 million children who missed out on the DTaP vaccine in 2019.

A previous report released by UNICEF earlier this year found that 67 million children across the world missed out on some or all routine vaccinations between 2019 and 2021, and 48 million didn't receive any doses over the same period.

The numbers were a reflection of how disruptive the COVID-19 pandemic has been on basic health services, Brian Keeley, editor-in-chief of UNICEF's annual report, State of the World's Children, told NPR this spring.

Families were on lockdown, clinics were closed, travel was difficult and countries had to make difficult choices on how to prioritize resources, Keeley said.

Still, while the apparent rebound is a positive development, the WHO and UNICEF warn that the recovery is not happening equally and is concentrated "in a few countries."

"Progress in well-resourced countries with large infant populations, such as India and Indonesia, masks slower recovery or even continued declines in most low-income countries, especially for measles vaccination," their statement reads.

The groups note that measles vaccination efforts have not recovered as well the other vaccines, "putting an addition 35.2 million children at risk."

"Beneath the positive trend lies a grave warning," UNICEF Executive Director Catherine Russell said. "Until more countries mend the gaps in routine immunization coverage, children everywhere will remain at risk of contracting and dying from diseases we can prevent. Viruses like measles do not recognize borders. Efforts must urgently be strengthened to catch up children who missed their vaccination, while restoring and further improving immunization services from pre-pandemic levels."