In August, 14 of Africa’s poorest countries, alongside international organisations and private companies, pledged over $45mn to the World Health Organisation (WHO)’s new Investment Round, which aims to raise $7.1bn in voluntary contributions to close its current funding gap for the next four years, improve primary care, and build a more robust, better-trained health workforce.Amid climate disruptions, pandemics, and rapid population ageing, the WHO estimates that its fundraising effort could save an additional 40mn lives over the next four years. The African Development Bank has committed $10mn, while countries like Ethiopia and Niger have each pledged $2mn.Earlier this month, countries and partner organisations from the WHO South-East Asia Region – including India, Indonesia, North Korea, and Sri Lanka – pledged $345mn.This raises an important question: if low-income countries like Chad and lower-middle-income countries like Côte d’Ivoire can contribute their fair share, will their wealthier counterparts step up?The WHO, which provides critical aid to roughly 166mn people in conflict zones such as Ukraine, Afghanistan, Yemen, Syria, South Sudan, and the Democratic Republic of the Congo, urgently requires more consistent and predictable funding.Otherwise, its ability to respond to health crises caused by wars, disease outbreaks, famines, droughts, and floods will be severely constrained, denying millions of people the emergency medical assistance they need.The WHO must also sustain its ongoing efforts in impoverished countries, where billions of people lack regular access to healthcare. In response to these evolving needs, the new Investment Round calls for just 0.1% of the $9tn spent annually on healthcare.When the WHO was founded after World War II, member states provided flexible funding that allowed for long-term planning. But nowadays, the organisation can be certain about only 20% of its budget and relies on voluntary, often earmarked, contributions for the rest, limiting its effectiveness. Even with institutional reforms underway, the current Investment Round is vital for securing the flexible funding required to implement the organisation’s strategy over the next four years.If Covid-19 has taught us anything, it is that health emergencies know no borders and that another pandemic is not a question of if, but when. Alarmingly, as global health threats grow more frequent and severe, the number of unvaccinated children is rising for the first time in modern history, exposing them to deadly diseases again. Moreover, communicable diseases have re-emerged as a leading cause of premature deaths.The climate crisis, too, is undeniably an escalating health crisis, with millions more people projected to die from malnutrition, cancer, malaria, air pollution, and extreme weather events. Meanwhile, the silent pandemic of antimicrobial resistance, which contributes to 5mn deaths annually, threatens to reverse a century of medical progress.Against this backdrop, the world is grappling with a profound mental health crisis. As our understanding of mental health disorders has deepened, it is now recognised that they are far more prevalent than previously thought. Notably, more than 700,000 people worldwide die by suicide each year.While health is enshrined as a human right in the constitutions of 140 countries, more than 4bn people lack access to basic care, leaving them so vulnerable that they cannot afford to get sick. Investing in healthcare is thus the best insurance policy to have. The results speak for themselves: every dollar invested in the WHO generates a remarkable $35 return in improved health outcomes. But the organisation’s 194 member states currently contribute just $0.30 per person annually to keep it afloat.Closing the funding gap is crucial for enabling the WHO to respond to the next pandemic swiftly and effectively. Of the $7.1bn it aims to raise, $1.6bn will be used for expanding healthcare in low- and middle-income countries – equivalent to just $0.13 per year from each of the 3bn people in the global middle class.With adequate funding over the next four years, the WHO can address gender-based health disparities, which account for 75mn years of life lost each year, by tackling issues such as post-partum haemorrhage, the leading cause of maternal deaths. These funds will also accelerate the implementation of the global strategy to accelerate the elimination of cervical cancer. And they will help finance the organisation’s Special Initiative for Mental Health, increasing support for the 1bn people living with mental health conditions.Altogether, fully funding the WHO’s programme of work for the next four years could prevent 40mn deaths by 2028, including 7.5mn deaths from climate-related causes, 6.5mn from noncommunicable diseases, and 5mn from infectious diseases.Moreover, it could improve health outcomes for 6bn people and provide access to healthcare for 5bn individuals facing financial hardship as a result of out-of-pocket expenses.The past few decades have shown what international co-operation, spearheaded by the WHO, can achieve. Co-ordinated global efforts have successfully eradicated smallpox, advanced the fight against tuberculosis, and reduced HIV deaths by 70% within 20 years. Over the past five years alone, it is estimated that 25 countries have eliminated at least one tropical disease, allowing the WHO to expand its efforts to eliminate 30 communicable diseases.Just imagine what can be accomplished in the next four years. A fully funded WHO could protect the world from health emergencies, reduce gender-based disparities, eliminate many more diseases, bridge the mental-health treatment gap, combat antimicrobial resistance, and ensure that displaced people worldwide have access to essential medical services.Achieving these goals depends on closing the current funding gap. In the face of what Martin Luther King, Jr, famously called the “fierce urgency of now,” the world cannot afford to wait. - Project Syndicate• Gordon Brown, a former prime minister of the United Kingdom, is UN Special Envoy for Global Education and Chair of Education Cannot Wait.