Some 67 million children partially or fully missed routine vaccines globally between 2019 and 2021 because of lockdowns and health care disruptions caused by the COVID-19 pandemic, the United Nations (UN) said Wednesday.

"More than a decade of hard-earned gains in routine childhood immunization have been eroded," read a new report from UNICEF, adding that getting back on track "will be challenging."

Of the 67 million children whose vaccinations were "severely disrupted," 48 million missed out on routine vaccines entirely, UNICEF said, flagging concerns about potential polio and measles outbreaks.

Vaccine coverage among children declined in 112 countries and the percentage of children vaccinated worldwide slipped five points to 81 percent – a low not seen since 2008. Africa and South Asia were particularly hard hit.

"Worryingly, the backsliding during the pandemic came at the end of a decade when, in broad terms, growth in childhood immunization had stagnated," the report said.

Vaccines save 4.4 million lives each year, a number the UN figures could jump to 5.8 million by 2030 if its ambitious targets to leave "no one behind" are met.

The report also raised concerns about a drop in people's confidence in vaccines, seen in 52 out of 55 countries surveyed.

"We cannot allow confidence in routine immunizations to become another victim of the pandemic," Catherine Russell, UNICEF's executive director, said in a statement. "Otherwise, the next wave of deaths could be of more children with measles, diphtheria or other preventable diseases."

Vaccine confidence can be "volatile and time specific," the report said, noting that "further analysis will be required to determine if the findings are indicative of a longer-term trend" beyond the pandemic.

Overall, it said that support for vaccines "remains relatively strong."

In about half of the 55 countries surveyed, more than 80 percent of respondents "perceived vaccines as important for children."

(With input from AFP)