Paramedics are trained to prioritise. Arriving at a traffic accident, they instinctively set about classifying the injured: first help those with the worst injuries, then those with less serious injuries.

Such triage is methodical, ensuring that everyone gets the right kind of help when it’s most needed.

In many ways, this is what we as humanitarians try to do after a disaster or in the midst of a crisis. We assess, prioritise, and respond. Speed matters, but so does completeness. We want to reach everyone who needs us.

So, what should we do when confronted with evidence that we consistently fall short of this goal?

A report released by the International Federation of Red Cross and Red Crescent Societies (IFRC) offers that evidence, stating that millions of people who need humanitarian assistance are being “left behind” in their moments of greatest need. It’s a sobering assessment for those of us at the IFRC and all of us who organise and run humanitarian assistance – donors; affected governments; and international, national, and local humanitarian NGOs and organisations. Early this year, the UN estimated that 134 million people would need humanitarian assistance in 2018.

UN-coordinated humanitarian operations – which also involve non-governmental organisations across the globe – are targeting about 97.4 million people. That leaves out 36.6 million.

Some are being assisted by national governments and members of the Red Cross and Red Crescent, domestic organisations, and faith-based groups. Nevertheless, many of these millions of people are still reached by no one.

And that’s only half the story. Even those who are prioritised to receive assistance are by no means guaranteed to receive it. In major emergencies – such as Afghanistan, Syria, the Democratic Republic of the Congo and Ukraine – the UN itself states that fewer than 60 per cent of the people in need of help actually received it.

Why this gap between ambition and reality? There are many reasons, but here are five major ones.

Money is the first and most often cited. The gap between the funds needed and the funds made available grows every year.

In 2017, only about 60 per cent of the $23.5 billion appealed for in UN donor campaigns was received. At the IFRC we grapple with shortfalls in funding on an almost daily basis.

Even if humanitarian budgets were fully funded, millions of people would still be left behind.

Lack of access is the second key challenge. In many crises, humanitarians cannot physically reach everyone in need. This could be for geographical or political reasons, including conflict and regional insecurity or bureaucratic and legal bottlenecks. We see it every day.

Right now, in the fight against Ebola in the DRC, our teams carrying out safe and dignified burials struggle to reach those who need assistance because of conflict and high levels of distrust within the communities.

Information or, more specifically, the lack of it is the third reason so many people in need are left without aid. It’s impossible to reach people if we can’t identify them or know where they are.

Culprits may include poor or non-existent mapping, particularly in remote areas and fast-growing urban slums.

Fourth is the knowledge gap that often arises from the way in which many humanitarian organisations function.

Groups of people in need are often inadvertently excluded because aid organisations lack the language skills and cultural insight to fully understand the situation. In addition, the assistance we do provide may not be appropriate for specific populations; people with disabilities, for example, or members of marginalised groups.

Finally, the very definition of “humanitarian work” is often a stumbling block. The UN figures I quoted earlier refer largely to people affected by conflicts and natural disasters.

People who have been spared those particular deprivations but who nevertheless live in states of crisis don’t receive help from anyone. They include families in parts of Central America who are caught in the midst of terrible urban violence or the millions of irregular migrants around the world who face death and cruelty on a daily basis.

What can we do? A first step is for the humanitarian sector to invest in confronting the challenge of “leaving no one behind”. The “value for money” quest should be a means and not an end for donors and aid groups. It may cost more to aid those hardest to reach, but reaching them and providing appropriate support is vitally important.

More broadly, as our report today suggests, local organisations hold the keys to helping many of those millions whose needs are unmet by the wider humanitarian community. Let’s place even more trust in local humanitarian organisations and invest more time and resources in their work. If vulnerable and under-supported communities are to be identified, reached, understood, and supported, then we must commit to working with local groups.

Such groups, including national Red Cross and Red Crescent Societies, are uniquely placed to help overcome the chronic gap in delivering aid. They are already present in crisis settings – before, during, and after the crisis.

They speak local languages, understand local customs, and are often best-placed to find and support the most isolated and vulnerable people in ways that are fast, culturally appropriate, and cost effective.

We – aid groups and donor governments – can begin to do this by making meaningful investments in strengthening the capacity of local organisations and by doing a better job of recognising the work they are already doing.

Let’s narrow the gap between our humanitarian ambition and the reality.