Global vaccination coverage continued to plunge in 2021, according to a new report

Last year, 25 million children missed out on one or more "lifesaving vaccines" according to a new report from the United Nations Children's Fund (UNICEF) and the World Health Organization (WHO).

"This is 2 million more than those who missed out in 2020 and 6 million more than in 2019, highlighting the growing number of children at risk from devastating but preventable diseases," the report notes. Those diseases include tuberculosis, diphtheria, tetanus, pertussis, polio, hepatitis B, measles, rubella, rotavirus, pneumonia, yellow fever and HPV.

The trend represents the largest "continued backslide" in childhood vaccinations in 30 years, says the report.

For example, the global vaccination rate against diphtheria, tetanus and pertussis (known as DTP3) fell from 86% in 2019 to 81% in 2021 – the lowest level since 2008, according to UNICEF. DTP3 is a marker for immunization coverage and is given in three doses. If children miss out on this vaccine, the likelihood is that they're missing out on many childhood vaccinations.

And while that percent slide may seem small, the total numbers are immense. According to the report, 18 million children didn't receive a single dose received of DTP during 2021, with the greatest numbers in India and Nigeria.

That compares to 16 million zero-dose DTP children in 2020 and 13 million in 2019.

The disruption caused by the pandemic is one of many reasons for the decline in childhood vaccination.

Other factors include "an increased number of children living in conflict and fragile settings where immunization access is often challenging" and "increased misinformation" about vaccines, according to the report.

"This is a red alert for child health," said Catherine Russell, UNICEF executive director, in a statement. "We are witnessing the largest sustained drop in childhood immunization in a generation. The consequences will be measured in lives.

"COVID-19 is not an excuse. We need immunization catch-ups for the missing millions or we will inevitably witness more outbreaks, more sick children and greater pressure on already strained health systems."

WHO and UNICEF also noted that this worrisome trend sits atop a mounting crisis of malnutrition, which weakens immune systems — making routine childhood illnesses increasingly fatal.

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