This past November, I met an extraordinary little boy named Fawaz in a hospital in Aden, Yemen. At 18 months old, Fawaz weighed a little more than 4 kg (9 lbs). Severely malnourished, Fawaz had been in the hospital for more than a month, barely able to hold the therapeutic milk he was being given. Yet, he persevered, determined to live. Fawaz's mother, Rokaya, was at his bedside day and night as if in a silent pact with her son to ensure that he prevailed.

Unlike most severely malnourished children, Fawaz did not respond well to the two types of therapeutic milk normally used to treat such children. After weeks of unsuccessful treatment and several blood transfusions, doctors switched to hypoallergenic milk, which is more expensive and had to be paid for by Fawaz's family.

Without this milk, Fawaz would not have recuperated. But his recovery came at a tremendous price for his family. Each milk tin costs about $30. For families who survive on a few dollars a day, this has devastating consequences. Medicine for one child means less food for the family, and one less meal a day means a heightened risk of malnutrition for the other children in the household.

This story does have a happy ending. Fawaz won. He left the hospital on 20 December and has continued to recover.

But millions more Yemenis are facing similarly dire conditions. One aid agency estimates that 85,000 children in Yemen may have lost their fight against starvation since 2015.

Out of a total of 20 million people who need help securing food, nearly 10 million are just a step away from famine. This includes almost 240,000 people who are facing catastrophic levels of hunger and barely surviving.

Only half of the health facilities in the country are fully functioning. Hundreds of thousands of people got sick this past year because of poor sanitation and waterborne diseases. Needs have intensified across all sectors. Millions of Yemenis are hungrier, sicker and more vulnerable today than they were a year ago.

The United Nations and humanitarian partners are doing our best to provide children such as Fawaz with a fighting chance.

Throughout 2018, despite one of the most dangerous and complex operational environments, some 254 international and national partners actively coordinated to provide even more people in Yemen with life-saving support. Together, we assist about 8 million people every month across the country - the largest aid operation in the world. In December alone, we reached a record number of more than 10 million people with food assistance.

But much more needs to be done. We know we can save millions of more lives this year. But we are running out of time. And we are running out of money.

That's why on 26 February, the United Nations will convene a high-level pledging conference in Geneva, co-hosted by the Governments of Sweden and Switzerland. Just over $4 billion is needed for the humanitarian response in Yemen this year, representing a 33 per cent increase since last year to provide not only food, but treatment for malnourished children such as Fawaz, health care, clean water and so much more.

The amount of money needed may sound large, but it will help reach 15 million Yemenis - about half of the population - by rolling back cholera, protecting children against deadly diseases, tackling malnutrition and improving living conditions for the most vulnerable people. Without additional funding, this simply cannot happen.

Donor countries have continued to give generously to the Yemen Humanitarian Response and we urge them to do so again this year. It is in all of our interests to prevent the humanitarian tragedy unfolding in Yemen from deteriorating further. I have every hope that our collective action in Geneva will save more lives and bolster the political process towards a peaceful solution.

We owe it to Yemen's children and their families.