The forthcoming election of a new leader of the World Health Organization (WHO) has focused attention on the future direction of the United Nations’ public-health agency. Supporters like to repurpose Voltaire’s famous line about God and argue that if the WHO didn’t exist, it would be necessary to invent it. But the organization is far from being omnipotent and all-powerful. In fact, it would benefit from trying to be a little less of both.

Along with an annual salary of just under US$240,000 and a high-profile role as the globe’s doctor-on-call, the new director-general will inherit staff who are being pulled in too many directions at once and whose employer is no longer as central to global health as it once was. The WHO member states are in large part to blame. In 1990, the WHO received$579 million in dues from its members, but this core budget has fallen to around $465 million this year. That’s less than the budget of many public-health agencies or large hospitals in rich countries. In 1990, the WHO and other UN agencies received more than half of the$8.5 billion available for global-health funding, and so had primacy. That funding has since ballooned to almost $40 billion. There is a plethora of new players with much greater financial clout, including the Bill & Melinda Gates Foundation, the Global Fund to Fight AIDS, Tuberculosis and Malaria, and Gavi, the Vaccine Alliance. Together, these new funders have revolutionized health in the world’s poorest countries. The launch earlier this month of a$1-billion initiative to preemptively research, develop and test vaccines against potential epidemic threats is a good example of what can be achieved by coordinating funding and efforts.

The choice of a successor to director-general Margaret Chan from the shortlisted nominees announced last week — Pakistan’s Sania Nishtar, the United Kingdom’s David Nabarro and Ethiopia’s Tedros Adhanom Ghebreyesus — is an important decision. Strong political leadership and foresight are needed to turn around the troubled agency, the reputation of which was tarnished by its initial slow response to the 2014 Ebola epidemic in West Africa. But no one should be under any illusions that a new head will be enough to trigger substantive change when he or she takes office in July.

That must begin with a realistic assessment of what the WHO is and is not — and what it can and cannot be reasonably expected to do. One problem is that the WHO has become dangerously dependent on voluntary contributions, which now make up more than 80% of its overall budget. Most of this money comes with strings attached by the funders to their own priorities, making it next to impossible for the WHO to have much of a say in its own agenda. As a result, the WHO’s programmes have proliferated but thinned.

Making matters worse, the agency is lumbered with a cumbersome and expensive organizational structure comprising a headquarters in Geneva, Switzerland, and six semi-autonomous regional offices. This has resulted in a complex, bureaucratic and ineffective management structure. It is a body that is ripe for root-and-branch reform. The upheaval is worth it because the WHO — at its best — is worth it.

Speak to researchers who work there and, apart from frustration with the often-stifling bureaucracy, the message that emerges is that when the WHO focuses and brings good people to the table, it has a unique and valuable part to play. This ranges from advancing agendas on mental health and getting its members to sign up to a tobacco-control treaty, to expediting clinical trials of an Ebola vaccine on the ground during the trying conditions of the West African epidemic.

The WHO’s coordinating role in developing the Ebola vaccine also highlights one of its unique benefits — no other body has the convening power of this intergovernmental agency, which can rapidly bring together scientists, industry, regulators and national public-health officials when needed.

To respond to crises, the WHO has also launched an emergency programme with a dedicated budget, workforce and command-and-control structure — although it remains to be seen how much funding it will attract and how effective it will be. But the WHO is not a global firefighter, and cannot be expected to be. Rather, it is a facilitator for more-operational organizations — key players such as the medical humanitarian organization Médecins Sans Frontières (also known as Doctors Without Borders) and national public-health authorities.

Tabletop exercises that simulate ways of tackling epidemics and pandemics show that the world remains woefully unprepared for such events. Ultimately, an effective frontline response depends on having functional public-health systems (which are still lacking in many places), preparing contingency plans so that interconnected global supply chains do not break down and planning for large outbreaks in cities, which are at increased risk as a result of rampant urbanization. The WHO has a crucial role in these and many other areas of public health as a facilitator and provider of sound scientific expertise. But it is ultimately down to the countries of the world to do the heavy lifting.