The United Nations kicked off a campaign to reverse dangerous declines in routine childhood vaccination as disruptions caused by the COVID-19 pandemic left some 67 million children fully or partially without vaccines, sparking rising outbreaks of diseases like measles and polio.
The World Health Organization (WHO) and the U.N. children's agency UNICEF, along with Gavi, the Gates Foundation and other partners launched "The Big Catch-up," to boost child vaccination worldwide.
"Millions of children and adolescents, particularly in lower-income countries, have missed out on life-saving vaccinations, while outbreaks of these deadly diseases have risen," WHO chief Tedros Adhanom Ghebreyesus said.
"Catching up is a top priority. No child should die of a vaccine-preventable disease."
The effort comes after essential immunization levels decreased in more than 100 countries as the COVID-19 pandemic raged, leading to overburdened health services, closed clinics, and disrupted imports and exports of medical supplies.
Communities also experienced lockdowns that restricted travel and access to services.
In 2021, more than 25 million children missed at least one vaccination, the WHO said, with 18 million of those missing out on routine vaccines entirely.
As a result, "outbreaks of preventable diseases, including measles, diphtheria, polio and yellow fever are already becoming more prevalent and severe," it said.
WHO said the campaign would focus in particular on 20 countries where three-quarters of all children who missed vaccines in 2021 live.
They are Afghanistan, Angola, Brazil, Cameroon, Chad, North Korea, the Democratic Republic of Congo, Ethiopia, India, Indonesia, Nigeria, Pakistan, Philippines, Somalia, Madagascar, Mexico, Mozambique, Myanmar, Tanzania and Vietnam.
WHO vaccines chief Kate O'Brien cautioned that the "sharp decline" in vaccination seen during the pandemic "follows almost a decade of stalled progress."
This, she told reporters, shows the need to "not only address the pandemic-related disruptions but also the systemic immunization challenges."
She said that the five-percent reduction in immunization seen from the pandemic backsliding had led to "at least a five-percent increase in mortality among children."
And that comes on top of the mortality that already exists due to existing gaps in vaccine coverage, with the deaths likely to multiply until immunization programs recover.
O'Brien said it was important to drive up vaccination rates against a number of diseases, highlighting in particular measles, which is a highly infectious and potentially deadly disease.
When immunization levels drop, "it leads to explosive outbreaks," she warned.
UNICEF chief Catherine Russell cautioned that the impact went beyond the threat from vaccine-preventable diseases.
"Routine vaccines are typically a child's first entry into their health system and so children who miss out on their early vaccines are at added risk of being cut out of health care in the long run," she said in the statement.
"The longer we wait to reach and vaccinate these children, the more vulnerable they become and the greater the risk of more deadly disease outbreaks."
