The UN warned on July 15 that a “perfect storm” was brewing, with a raging pandemic disrupting access to routine vaccinations, leaving millions of children at risk from measles and other deadly diseases.

A full 23 million children missed out on basic childhood vaccines last year, as routine health services were hit worldwide by restrictions aimed at controlling Covid-19 and many parents shunned the clinics that were open for fear of exposure to the virus.

It marks the highest number in over a decade and 3.7 million more than in 2019, according to data published Thursday by the World Health Organisation (WHO) and the UN’s children’s agency UNICEF.

And the sharp decline in routine vaccinations comes as many countries have begun loosening restrictions even as the pandemic is far from over.

This has the potential of not only driving up Covid transmission, but also of allowing otherwise vaccine-preventable diseases to begin spreading.

That is because the restrictions in many countries have until now also provided a buffer protecting unvaccinated children against exposure to childhood diseases.

“In 2021, we have potentially a perfect storm about to happen,” Kate O’Brien, head of the WHO’s vaccines and immunisation department, told reporters.

“This is the sort of perfect storm we’re ringing the alarm bell about right now,” she said. “We need to act now in order to protect these children.”

The data published on July 15 revealed that rising numbers of children across all regions missed first vital vaccine doses last year while millions more missed later vaccines.

Compared with 2019, 3.5 million more children missed their first doses of the three-dose diphtheria, tetanus and pertussis vaccine (DTP) while three million more children missed their first measles dose, the data showed.

Even more concerning perhaps, as many as 17 million children, mainly living in conflict-affected communities or in under-serviced remote areas or in informal slum settings, likely did not receive a single vaccine last year.

“The Covid-19 pandemic and related disruptions cost us valuable ground we cannot afford to lose,” UNICEF chief Henrietta Fore said in the statement, cautioning that “the consequences will be paid in the lives and wellbeing of the most vulnerable”.

Even before Covid, “there were worrying signs that we were beginning to lose ground in the fight to immunise children against preventable child illness”, she said. “The pandemic has made a bad situation worse.”

Global coverage for all three DTP doses had for instance stalled at 86 per cent over recent years, but then slumped to 83 per cent last year, meaning 22.7 million children missed out.

As for measles, which is highly contagious and requires vaccination uptake of at least 95 per cent to avoid spread, the first-dose vaccination rate slipped from 86 to 84 per cent last year, while only 71 per cent received a second dose.

The situation meanwhile varies greatly, with the data showing a particularly sharp drop in vaccination rates in Southeast Asia.

In India, which has been ravaged by a devastating second Covid wave, the number of children who missed their first DTP dose more than doubled to over three million last year from 1.4 million in 2019.

Coverage for all three DTP doses in the country meanwhile fell from 91 to 85 percent, the data showed.

Pakistan, Indonesia and the Philippines also saw the number of unprotected children rise significantly.

The UN has warned against sacrificing routine childhood vaccines in the rush to roll out Covid jabs.

“Even as countries clamour to get their hands on Covid-19 vaccines, we have gone backwards on other vaccinations, leaving children at risk from devastating but preventable diseases like measles, polio or meningitis,” WHO chief Tedros Adhanom Ghebreyesus warned in the statement.

“Multiple disease outbreaks would be catastrophic for communities and health systems already battling Covid-19, making it more urgent than ever to invest in childhood vaccination and ensure every child is reached.”