Progress in vaccinating children against a variety of life-threatening diseases has stalled in the past two decades – and even gone backwards in some countries – a new global study suggests.

The situation has been made worse by the Covid pandemic, leaving millions of children unprotected from diseases such as measles, tuberculosis and polio.

The researchers are calling for a concerted effort to provide better and more equal access to vaccines.

Child health experts warn that cuts to international aid budgets that fund vaccination programmes, combined with vaccine scepticism, are creating a “perfect storm”.

The global childhood vaccination programme has been a huge success.

Since 1974, more than four billion children have been vaccinated, preventing an estimated 150 million deaths worldwide.

In nearly half a century until 2023, researchers say vaccine coverage doubled.

But since 2010 progress has stagnated, to the extent that there are now wide variations in vaccine coverage around the world.

A study, published in the medical journal The Lancetsays measles vaccinations have declined in nearly 100 countries.

The Covid-19 pandemic made things even worse, because of disruption to vaccine programmes during lockdowns.

By 2023, there were nearly 16 million children who had not had any childhood vaccinations – most of them in sub-Saharan Africa and south Asia.

Study author Dr Jonathan Mosser, from the Institute for Health Metrics and Evaluation at the University of Washington, in the United States, says large numbers of children remain under-vaccinated and un-vaccinated.

“Routine childhood vaccinations are among the most powerful and cost-effective public health interventions available, but persistent global inequalities, challenges from the Covid pandemic, and the growth of vaccine misinformation and hesitancy have all contributed to faltering immunisation progress,” he said.

Dr Mosser said there was now increased the risk of outbreaks of diseases such as measles, polio and diphtheria.

All children should benefit from life-saving immunisations, he added.

Wide discrepancies remain between vaccination rates in wealthier and lower-income countries.

But the report’s authors warn that vaccination rates have fallen in Europe, the US and other wealthy countries too.

Professor Sir Andrew Pollard, director of the Oxford Vaccine Group, says the findings present a concerning picture.

“More children will be hospitalised, permanently damaged and die from fully preventable diseases if the trend is not reversed.

“Alas, the cuts in global health funding mean that this situation is set to deteriorate,” Prof Pollard said.

Dr David Elliman, from University College London, says many factors have contributed to the current situation.

“Around the world, the increasing number of countries torn apart by civil unrest and wars, combined with the drastic cuts in foreign aid from rich nations, such as USA and UK, makes it difficult to get vaccines to many populations,” he said.

“Where it appears that policy is being made on the basis of ill-informed opinion, rather than science, we have a perfect storm,” Dr Elliman added.

The researchers recommend that all countries try to strengthen primary healthcare systems and combat misinformation around vaccines to prevent parents being hesitant about getting their children vaccinated.

They also call for a concerted effort to provide better and more equal access to vaccines around the world.