The most consequential global health challenges are no longer principally about single diseases. They are about systems that cannot meet changing demand, threats that no country can address alone, and the widening gap between what medicine can do and what most of the world's population can actually obtain.
This guide sets out the major challenges, why each is difficult, and where the evidence on responses stands. They are interconnected: workforce shortages limit outbreak response, climate change drives displacement and disease distribution, and financing constraints affect every other item on the list.
The Epidemiological Transition and Non-Communicable Disease
Cardiovascular disease, cancer, chronic respiratory disease, and diabetes now account for the majority of deaths globally. This is not exclusively a high-income phenomenon: the majority of deaths from these conditions occur in low- and middle-income countries, often at younger ages than in wealthier settings.
The difficulty is structural. Health systems in many countries were built around episodic care for acute illness and are poorly configured for conditions requiring lifelong management, continuity, reliable medicine supply, and self-management support. Financing has also lagged: development assistance has historically concentrated on infectious disease, maternal and child health, and immunisation.
Established cost-effective interventions exist — tobacco control, salt reduction, hypertension management with generic medicines, cervical cancer screening and HPV vaccination — but implementation is uneven, and many depend on primary care capacity that is itself constrained. Several NCD risk factors are shaped by commercial determinants including tobacco, alcohol, and ultra-processed food marketing, which places parts of the response in regulatory and trade policy rather than in health services.
Antimicrobial Resistance
Antimicrobial resistance occurs when microorganisms evolve so that treatments previously effective against them no longer work. It threatens not only treatment of infection but the safety of surgery, chemotherapy, transplantation, and neonatal care, all of which depend on the ability to prevent and treat infection.
Drivers include overuse and misuse of antimicrobials in human medicine, extensive use in agriculture and animal production, inadequate infection prevention and control, poor water and sanitation, weak diagnostic capacity leading to empirical prescribing, and availability of antimicrobials without prescription in many settings.
The response is genuinely difficult because it requires action across sectors — the One Health framing linking human, animal, and environmental health — and because the commercial model for antibiotic development is broken: a valuable new antibiotic should be used sparingly and reserved, which conflicts directly with recovering development costs through sales volume. Proposed responses include delinked payment models such as subscription arrangements that pay for access rather than volume, alongside stewardship programmes, improved diagnostics, infection prevention, and surveillance.
Health Workforce Shortage and Maldistribution
WHO has repeatedly identified a substantial global shortfall in health workers, concentrated in low- and lower-middle-income countries and most acute in nursing, midwifery, and primary care.
Distribution compounds absolute shortage. Rural and remote areas are under-served in almost every country. International migration moves health workers from lower- to higher-income countries, benefiting individuals and destination systems while depleting the systems that trained them; the WHO Global Code of Practice sets ethical recruitment principles and identifies countries facing the most pressing shortages. Retention is affected by pay, working conditions, safety, and career progression, and attrition frequently exceeds what recruitment can replace.
Pandemic and Epidemic Preparedness
Outbreak risk is persistent, driven by land-use change, intensive animal production, urbanisation, travel, and climate-driven shifts in vector distribution. The International Health Regulations require states to develop core surveillance and response capacities and to notify events that may constitute a public health emergency of international concern, but assessments have repeatedly found capacity uneven.
Recognised weaknesses include gaps in surveillance and laboratory capacity, delays in detection and reporting, limited surge capacity in health systems, and profound inequity in access to countermeasures — vaccines, therapeutics, diagnostics, and protective equipment — during emergencies. Responses under development include strengthened financing mechanisms, regional manufacturing capacity, technology transfer arrangements, and negotiated instruments addressing information sharing and equitable access.
Climate Change and Environmental Health
Climate change affects health through multiple pathways: heat-related illness and mortality; extreme weather events causing injury, displacement, and infrastructure damage; changing distribution of vector-borne diseases as temperature and rainfall patterns shift; food and water insecurity affecting nutrition; air pollution, which shares major sources with greenhouse gas emissions and is itself a leading environmental risk factor; and mental health effects of displacement and loss.
Health systems face a dual task: adapting to these effects while reducing their own substantial emissions, since healthcare is itself a significant contributor. Effects are distributed inequitably, falling heaviest on populations that contributed least to the underlying emissions.
Mental Health
Mental health conditions contribute substantially to global disability while receiving a small fraction of health spending in most countries. Treatment gaps are among the widest in health, with the majority of people with common mental disorders receiving no treatment in many settings.
Barriers include workforce shortage in mental health specialties, stigma, absence of services outside specialist facilities, inadequate financing, and in some countries continuing reliance on institutional care rather than community-based services. Evidence supports integrating mental health into primary care and task-sharing with trained non-specialist workers, an approach reflected in WHO programmes designed for settings with few specialists.
Access to Medicines, Vaccines, and Diagnostics
Access is constrained by affordability, supply chain reliability, regulatory capacity, and manufacturing concentration. Additional challenges include substandard and falsified medical products circulating where regulatory oversight is weak; limited diagnostic capacity, which drives empirical treatment and contributes to resistance; geographic concentration of manufacturing, creating vulnerability during supply disruption; and limited commercial incentive to develop products for diseases affecting populations with low ability to pay.
Mechanisms addressing these include WHO prequalification, the Essential Medicines and Essential Diagnostics Lists, pooled procurement, voluntary licensing and technology transfer arrangements, and product development partnerships for neglected diseases.
Health Financing and Financial Protection
Many people worldwide face catastrophic health expenditure or are pushed into poverty by health costs, and many forgo needed care because of cost. Out-of-pocket payment at the point of service is the financing mechanism most strongly associated with these harms.
Challenges include limited fiscal space for health in low-income countries, dependence on external financing that may not be sustained, inefficiency in how existing resources are used, and the transition faced by countries as they grow economically and become ineligible for concessional financing before domestic systems can absorb the cost.
Maternal, Newborn, and Child Health
Substantial progress has been made over recent decades, but maternal and newborn mortality remain unacceptably high in several regions and progress has slowed. Deaths are concentrated in settings with limited access to skilled birth attendance, emergency obstetric care, and functioning referral systems. Most maternal deaths are considered preventable with existing knowledge and interventions, making this a health system and access problem rather than a scientific one.
Conflict, Displacement, and Humanitarian Crises
Armed conflict destroys health infrastructure, displaces populations and health workers, interrupts immunisation and treatment programmes, and creates conditions for outbreaks. Attacks on healthcare facilities and personnel are documented in multiple conflicts despite protections under international humanitarian law. Displaced populations face barriers to care in host settings, and protracted displacement creates long-term health needs that emergency response models are not designed to meet.
Health Inequity Within Countries
Differences in health outcomes within countries are frequently as large as differences between them. Life expectancy varies substantially between neighbourhoods in the same city. These gradients follow income, education, occupation, ethnicity, gender, disability, and geography, and they reflect the conditions in which people are born, grow, live, work, and age more than differences in health service quality. Addressing them requires action across sectors — housing, education, income, environment — which sits outside health ministries' direct control.
Sources
- World Health Organization — Global Action Plan on Antimicrobial Resistance; NCD global action plan; Global Strategy on Human Resources for Health; climate change and health guidance; mental health action plan
- United Nations — Sustainable Development Goals
- World Bank — health financing and universal health coverage analysis
- Institute for Health Metrics and Evaluation — Global Burden of Disease study
- WHO — International Health Regulations; Global Code of Practice on International Recruitment of Health Personnel
- Intergovernmental Panel on Climate Change — health impacts assessment
