Countries experiencing armed conflict tend to report more measles cases, and the elevated risk persists even a year after the fighting, according to new research published in PLOS Medicine .
The study links armed conflict to measles in two ways: directly through disrupting immunization programs, and—more powerfully—indirectly by eroding a country's economic, educational, and health foundations that protect populations from preventable disease.
Countries experiencing violence are known to have outbreaks of preventable infectious diseases, driven by a number of factors including weakened health systems, missed vaccines, and population displacement. For instance, when families are forced to flee their homes and children no longer have access to routine vaccines, pockets of vulnerability form that can seed new outbreaks.
Past studies of armed conflict and infectious diseases have been limited to single countries or short timeframes, leaving gaps in our understanding of how armed conflict shapes disease outcomes across the globe.
"We get reports from conflict-affected settings of polio outbreaks or measles making a comeback. But it's very hard to marry conflict data and public health data to understand the impact of conflict on health," said Yesim Tozan , associate professor of global health at NYU's School of Global Public Health and the study's senior author. "Whenever an external shock strikes—a natural disaster, a pandemic, or armed conflict—it tests the health system's resilience. During these crises, policymakers need an understanding of how the external shocks may lead to increased infectious disease burden."
To examine these questions from a global perspective, the researchers developed and tested four statistical models linking armed conflict, population displacement, and socioeconomic development to measles cases across 193 countries. Their analyses of longitudinal country-level data—from 2000 to 2023—included battle-related deaths, displacement, economic output, life expectancy, and education. They compared these factors with total measles cases and incidence per million people.
The researchers found that higher levels of armed conflict, measured by battle-related deaths, were associated with more measles cases. On average, for roughly every 3,700 battle-related deaths in a country in a given year, there were about 2,500 additional reported measles cases.
The researchers showed that both direct and indirect factors connected armed conflict with measles, but socioeconomic decline—an indirect influence—was the strongest pathway. Armed conflict and population displacement were each associated with lower socioeconomic development, and that decline was, in turn, strongly associated with a higher measles burden. In some models, the influence of population displacement operated largely through this socioeconomic pathway rather than directly, underscoring the importance of the damage that conflict does to economies, education, and health systems.
"Health system resilience—how well a system can reorganize itself so that service delivery isn't interrupted—is very much connected to a country's socioeconomic development," said Tozan.
Notably, the association did not disappear once the fighting eased, demonstrating that the link between conflict and health outcomes is durable and likely extends beyond the period of active violence.
The findings suggest that mitigating infectious disease risks in volatile settings requires a multi-faceted strategy, including sustaining vaccination programs in conflict-affected areas, extending outreach to displaced populations and including them in immunization programs, and bolstering the broader socioeconomic resilience that protects health over the long term.
"Conflict-affected settings may lose infrastructure, health workers, and people's trust," said Tozan. "From a public health perspective, we need to ensure that critical, life-saving services carry on even while violence is occurring, and recovery requires continued investment so that those systems can bounce back."
