Aid cuts could lead to more than 22 million avoidable deaths by 2030, including 5.4 million children under five, according to the most comprehensive modelling to date.

In the past two decades there have been dramatic falls in the number of young children dying from infectious diseases, driven by aid directed to the developing world, researchers wrote in the Lancet Global Health. But that progress was at risk of reversal because of abrupt budget cuts by donor countries, including the US and the UK.

The researchers looked at the link between how much aid countries received and their death rates between 2002 and 2021, and then used the data to forecast three future scenarios.

One was “business-as-usual”, the second assumed a “mild defunding” where aid fell by a similar amount as it had over the past few years, and the third “severe defunding”, where aid fell to about half its 2025 levels until the end of the decade.

Under severe defunding, about 22.6 million more deaths were forecast by 2030, including 5.4 million among under-fives. Mild defunding would mean 9.4 million excess deaths, of which 2.5 million would be young children.