ACCRA, Ghana – Large outbreaks of diseases that primarily kill children are spreading around the world, a grim legacy of disruptions to health systems during the Covid-19 pandemic that have left more than 60 million children without a single dose of standard childhood vaccines.

By midway through 2023, 47 countries were reporting serious measles outbreaks, compared with 16 countries in June 2020.

Nigeria is currently facing the largest diphtheria outbreak in its history, with more than 17,000 suspected cases and nearly 600 deaths so far. Twelve countries, from Afghanistan to Zimbabwe, are reporting circulating polio virus.

Many of the children who missed their shots have now aged out of routine immunisation programmes.

So-called “zero-dose children” account for nearly half of all child deaths from vaccine-preventable illnesses, according to Gavi, the organisation that helps fund vaccination in low- and middle-income countries.

An additional 85 million children are under-immunised as a result of the Covid-19 pandemic – that is, they received only part of the standard course of several shots required to be fully protected from a particular disease.

The cost of the failure to reach those children is swiftly becoming clear. Deaths from measles rose 43 per cent to 136,200 in 2022, compared with the previous year, according to a new report from the World Health Organisation and the US Centres for Disease Control and Prevention. The figures for 2023 indicate that the total could be twice as high again.

“The decline in vaccination coverage during the Covid-19 pandemic led us directly to this situation of rising diseases and child deaths,” said Dr Ephrem Lemango, associate director of immunisation for United Nations children’s agency Unicef, which supports delivery of vaccines to almost half the world’s children every year.

“With each new outbreak, the toll on vulnerable communities rises. We need to move fast now and make the investment needed to catch up the children that were missed during the pandemic.”

One of the biggest challenges is that the children who missed their first shots between 2020 and 2022 are now older than the age group typically seen routinely at primary healthcare centres and in normal vaccination programmes.

Reaching and protecting them from diseases that can easily turn fatal in countries with the most fragile health systems will require an extra push and new investment.

“If you were born within a certain period of time, you were missed, full stop, and you’re not going to get caught just by restoring normal services,” said Ms Lily Caprani, Unicef’s chief of global advocacy.

Unicef is asking Gavi for US$350 million (S$468.9 million) to purchase vaccines to try to reach those children. Gavi’s governing board will consider the request in December.

Unicef is urging countries to implement a catch-up vaccination blitz, an exceptional, one-time programme to reach all the children between the ages of one and four who were missed.

Many developing countries have some experience of carrying out catch-up campaigns for measles, targeting children between one and five, or even one and 15, in response to outbreaks.

But now those countries also need to deliver other vaccines and train personnel – typically community health workers who are accustomed to vaccinating only babies – and to procure and distribute the actual vaccines.

Dr Lemango said that despite the urgency of the situation, it had been a struggle to get plans for such campaigns in place, and he hoped most of them could come together in 2024.

“Coming out of the pandemic, there was this hangover; no one wanted to do campaigns,” he said. “Everyone wants to return to normality and do regular strengthening of immunisation. But we already had unfinished business.”

The countries with the most zero-dose children include Nigeria, Ethiopia, India, the Democratic Republic of Congo and Pakistan.

Many with the lowest levels of coverage are facing compounding challenges, such as civil conflicts in Syria, Ethiopia and Yemen; the growing population of climate refugees in Chad; and both of those problems in Sudan.

Ghana’s experience is representative of the challenges of many lower-income countries.

Parents could not take their children for routine shots when communities were locked down to protect against Covid-19. When those restrictions were lifted, many parents still stayed away because of fear of infection, said Ms Priscilla Obiri, a community health nurse in charge of vaccinations in low-income fishing communities on the edge of the capital, Accra.

Of the children Ms Obiri sees these days at a typical pop-up vaccination clinic, where she sets up a table and a few chairs in the shade at a crossroads, as many as one-third have incomplete vaccinations or sometimes none at all, she said. She agrees on a plan with their mothers to make up the gap.

But some parents do not or cannot take their children to a clinic. “We must go out to the community and hunt for them,” she said.

As Ms Obiri and her colleagues attempt to regain that lost ground, they face another challenge: Disinformation campaigns and hesitation about Covid-19 vaccines have spilt over and eroded some of the traditional eagerness that parents had to get their children routine immunisations, according to the Vaccine Confidence Project, a long-running research initiative at the London School of Hygiene and Tropical Medicine.

“In 55 countries, there was a precipitous drop between 2015 and 2022 in the number of people who said that routine immunisation is important for children,” said the project’s director, Professor Heidi Larson, whose team collected what she described as “robust global polling data” in more than 100 nationally representative surveys.

Even as people around the world were seeking information about vaccines, there was a surge in misinformation and disinformation, she said, and people with low trust in officials and official guidance were particularly vulnerable to believing alternative sources of information.

In 2015, 95 per cent of Ghanaian parents said they believed vaccines were safe. That figure plunged to 67 per cent of parents in 2022. It had climbed back to 83 per cent by October 2023.

Dr Kwame Amponsah-Achiano, who oversees the childhood immunisation programme in Ghana, said he did not believe that confidence had fallen during the Covid-19 pandemic. Demand remains high and has outstripped the programme’s ability to supply in some areas, he said.

Ms Caprani said Unicef had found that both problems were occurring in parallel.

“You can have demand outstripping not just physical supply but also outstripping access – convenient, affordable, reachable access – and simultaneously see some declining confidence,” she said. “It’s not necessarily the same people.” NYTIMES