On this World Health Day, 7 April, the World Health Organization marks its 70th anniversary.

It has notched up some notable achievements such as the efforts to eradicate diseases like smallpox, a convention on tobacco control and a framework to prevent flu pandemics. Alongside this runs coordinating work on global standards and guidelines for essential drugs, diagnosis, treatment and health workers.

World Health Day this year will focus on one of WHO’s founding principles: “The enjoyment of the highest attainable standard of health is one of the fundamental rights of every human being without distinction of race, religion, political belief, economic or social condition.”

This language and the creation of the World Health Organization on 7 April 1948 reflect the post-war times. Leaders, galvanised by the devastation of the years of conflict, were open to building societies afresh, incorporating basic values such as the right to health.

That same year, the UN adopted the Universal Declaration of Human Rights and the UK set up a National Health Service to meet the needs of its population regardless of income or social access, and the country has reaped the social and economic gains ever since.

Since then, WHO’s membership has tripled to 194 member states, with developing countries now in the majority. The organisation relies on the interest of states being met by working together for the greater good, to prevent infectious diseases like Sars from crossing borders, for example, or to tackle common risks like drug resistance. But huge inequities in health provision between richer and poorer countries persist. While Europe and America might prioritise health security, for many developing countries, providing fairer access to quality healthcare must come first.

The challenge of increasing drug resistance highlights the complexities of the WHO’s role. The organisation has warned that too few antibiotics are in the pipeline to tackle the rise of infections that are close to untreatable. While research and development play a part, controlling access to antibiotics is also vital. In poorer states, the health systems aren’t always in place to facilitate that – if the majority of your population don’t have dependable access to a doctor or nurse qualified to prescribe, and would therefore be at risk of dying from an infection for want of a signature, how can you enforce such restrictions?

The election last year of Ethiopian Dr Tedros Adhanom Ghebreyesus as WHO’s director general is part of the slow shift to greater representation for developing countries. Tedros has a fine line to walk for his five-year term if he is to keep donor confidence to raise core funds and maintain the organisation’s independence, while delivering on WHO’s founding remit.

Wealthier countries still use their financial influence. Only 20% of WHO’s activity is untied core funding from member states. The remaining 80%, a combination of government funding, philanthropy and the private sector, is money earmarked for specific projects. Without greater member state contributions, this looks to be the WHO’s reality.

The field of global health has become a more crowded place. The World Bank secured significant funds in the misguided structural adjustment era championing user fees and so was able to sweeten advice with loans and grants. More recently the arrival of the more narrowly defined remits and nimbler decision-making of the Global Fund (to fight Aids, tuberculosis and malaria) and the vaccine alliance Gavi have also attracted significant funds.

The appointment of a health professional, Jim Yong Kim, as president of the World Bank, with invaluable experience of healthcare in resource-strapped settings, was encouraging. Yet the Bank can do more. There is an inherent contradiction if another part of the organisation is advising investment in countries with low tax regimes when public finance has been shown to be key to delivering sustainable health services.

Growth won’t bring countries prosperity without ensuring citizens’ core health needs are met – health has a huge impact on economic and social development. An international body like the WHO can’t deliver universal access alone but must convince national governments to invest in health.

The previous director general, Margaret Chan, found a way to make member states cooperate again but as the Ebola crisis showed, some tensions still need tackling. Tedros has a diplomatic tightrope to walk. Despite an early misstep over the Mugabe appointment, there is still good will for his tenure and he will need to deploy all his political skills to ensure the next 70 years bring us closer to health access for everyone.

For all its imperfections, WHO still has a vital role. We need its convening power as much as we did in 1948. Its failings reflect our current global health inequality and its challenges the politics of redressing this.