LONDON: Rapid urban growth poses a big challenge for efforts to vaccinate the world’s poorest children and increases the risk of rapidly spreading disease outbreaks, the head of immunisation at the U.N. children’s agency said.

A growing number of unvaccinated children live in city slums, where immunisation coverage is limited, said Robin Nandy, principal adviser and chief of immunisation at UNICEF.

“We’re particularly worried about disease outbreaks in urban settings because they have the potential to spread fast and affect a large number of people,” Nandy told the Thomson Reuters Foundation.

By 2030, an estimated 1 in 4 people will live in urban slums and informal settlements, mainly in Africa and Asia, in dire need of clean water, energy, food, sanitation and health services, according to the United Nations.

The 2014 Ebola outbreak in West Africa showed how fast disease outbreaks can spread in cities, said Nandy.

“One of the complexities…was the fact that cities were affected. In urban areas communicable diseases like Ebola spread faster and the outbreak lasted longer than previous (ones) that had been limited to rural settings,” he said.

Another example was the deadly yellow fever outbreak in Angola and the Democratic Republic of Congo last year which spread fast in the capitals of Luanda and Kinshasa, Nandy said.

“One thing that adds to the complexity in cities is that often these megacities have a different administrative structure than rural districts…,” said Nandy, an epidemiologist and public health physician.

Growing numbers of refugees coming to cities add to immunisation challenges, in particular as many of them may not have been vaccinated due to a breakdown of health services in their conflict-ridden home areas.

“They are particularly vulnerable because they may also lack access to water and sanitation and nutrition services and therefore are more likely to die as a result of vaccine preventable disease like measles,” said Nandy.

In famine-threatened Somalia, thousands of children have been infected by measles, UNICEF said this week, as it launched a campaign to vaccinate some 360,000 children in one month.

Many of the children have never been immunised before as they have come to cities such as Baidoa in central Somalia from remote areas health workers often cannot reach due to conflict.


Access to immunisation in the past two decades has led to a dramatic drop in deaths of children under five from vaccine-preventable diseases such as measles and tetanus.

It has also brought the world closer to eradicating polio, with only Nigeria, Pakistan and Afghanistan still affected.

Between 2000 and 2015 under five-year-old deaths from measles dropped 85 percent and those due to neonatal tetanus by 83 percent, according to UNICEF.

But such success has led to complacency, and 1.5 million children still die every year from diseases that could be prevented through vaccination, said Nandy.

“Vaccination programmes have been very successful over the past two decades but complacency has set in among public health practitioners, governments and also donors who feel that immunisation is a done deal because it has reached achieved 85 percent coverage globally,” said Nandy.Around 19.4 million children still miss out on full vaccinations every year, many of them in areas affected by conflict, while weak health systems, poverty and social inequality also mean one in five children under five is still not reached with life-saving vaccines.

The poorest children are nearly twice as likely to die before the age of five than the richest, and in countries where 80 per cent of under-five child deaths occur, over half of the poorest children are not fully vaccinated, according to UNICEF.

Nandy said he was concerned about recent outbreaks of highly-contagious measles both in rich and poor countries.

“If we drop our guard, measles can come back and cause unnecessary illness and deaths among children.”