US President Joe Biden’s decision to back the call for waiving intellectual-property protections for Covid-19 vaccines reflects the extent of global pressure for universal vaccine access. Yet the world’s poor suffer from many other preventable and treatable diseases, with dire social and economic consequences.

Neglected tropical diseases—such as elephantiasis, trachoma, river blindness, and intestinal worm infections—are virtually nonexistent in advanced economies. But among people living in extreme poverty, they are the most common infections. About a billion people worldwide—including more than 750 million people living below the World Bank poverty line of $1.90 per day—suffer from NTDs every year.

Their suffering can be extreme. NTDs cause severe pain and long-term disability, often leading to social stigmatisation. Among children, infection interrupts education and causes malnutrition, impairing intellectual and cognitive development and stunting growth. And by interfering with education and employment, NTDs keep people trapped in poverty.

And yet, while nearly 17 million healthy years of life are lost annually to NTDs, these diseases are largely preventable, and many can be treated with a few simple pills. Ensuring broad access to these medications would not only bring obvious health and humanitarian benefits, but also pay remarkably high and sustained social and economic dividends.

Consider intestinal worms, the most prevalent—and among the most treatable—NTDs. Starting in 1998, we studied a public health programme providing treatment for intestinal worms to tens of thousands of primary-school children in Kenya. Using a randomised control trial, we could reliably measure the programme’s causal impact by comparing schools where treatment was provided with otherwise identical schools where it wasn’t.

In the schools that received treatment, we recorded gains in child-health measures and considerably higher school attendance. We then engaged in a two-decade effort to track a representative subsample of thousands of the same children. Roughly every five years, the research team carried out surveys to gather information on these individuals’ earnings and living standards, as well as residential choices and other life outcomes.

The results from this unusual longitudinal data set are stunning. Twenty years later, individuals who had received additional deworming treatment in school—now in their late twenties and early thirties—reported 13 percent higher hourly wages and 14 percent higher spending on consumption goods than those who did not. They had also moved to large urban areas, like Nairobi, in far greater numbers, affording them better economic opportunities.

Considering that an annual deworming treatment costs about $0.50 per child when delivered at scale, the rate of return on this investment in child health is astronomical and pays for itself many times over. Fortunately, governments in India, Kenya, Nigeria, Ethiopia, and Pakistan have recognised this, and are working with NGOs to implement mass deworming programmes that currently reach over 280 million children each year. But there is still much work to be done to reach the nearly 600 million children who remain at risk of parasitic worm infections.

The same is true of NTDs more broadly. Over the last two decades, governments, nonprofit organisations, and bilateral and private donors have made enormous progress in the fight against these diseases, using extremely cheap, cost-effective treatments. As a result, we are closer to beating NTDs than ever. But we aren’t there yet.

With the Covid-19 pandemic pushing even more of the world’s population into poverty—and increasing the risk of debilitating illness—now is the time to redouble our efforts to combat NTDs. But growing demands on government budgets and more competition for funding seem set to halt progress—and even reverse it.

The British government—a global leader in innovative foreign-assistance programmes—recently announced that it would cut 90 percent of its funding for NTDs. As a result of this decision, millions of people will miss out on treatments, and many medicines that are already in-country could expire on the shelf, owing to a lack of funds to distribute them. For the world’s most vulnerable populations, the consequences will be catastrophic.

That is why we urge the British government to reverse its decision, and encourage other governments to fill the gaps in funding. NTD interventions are some of the most cost-effective global health investments countries can make, especially at a time of rising poverty and proliferating disease. To end the scourge of NTDs and protect the world’s poorest people, we must neglect neglected tropical diseases no more.