Beyond biological threats: A global ecological study of International Health Regulations (2005) core capacities and multi-hazard disaster outcomes, 2015–2023

Every year, the world faces a chaotic mix of crises: earthquakes that shatter cities, floods that drown communities, and storms that tear through coastlines. In the midst of this physical destruction, a second, invisible battle begins. Health systems, already strained, must suddenly care for the injured, prevent outbreaks of disease, and keep hospitals running when roads are blocked and power lines are down. For decades, global health leaders have operated under the assumption that the skills needed to stop a virus are the same skills needed to survive a hurricane. This idea is the foundation of the International Health Regulations, a global agreement signed in 2005 that asks every country to build specific strengths, or "core capacities," to handle public health emergencies. These strengths include things like having a strong network of laboratories to test samples, a workforce of trained health workers, and a system to communicate risks to the public. The regulations were designed to catch biological threats, but their rules are broad enough to cover any kind of disaster.

The big question, however, has remained unanswered: do these health systems actually work when the threat isn't a virus? Do countries that have built strong health defenses against disease also suffer fewer deaths and injuries when nature strikes? A new study set out to find the answer by looking at the last nine years of global history. Researchers gathered data from 196 countries, comparing how well each nation had built its health defenses against the actual number of people who died or got sick during disasters. They looked at two different global databases to ensure their findings were solid, checking whether the countries with the highest scores for health preparedness were the ones that fared best when floods, fires, or earthquakes hit.

The researchers focused on a specific set of nine skills that countries report on every year. These include the ability to coordinate different government agencies, the strength of their surveillance systems to spot problems early, the quality of their laboratories, and the availability of health services. They created a single score for each country based on how well they had developed these nine areas. Then, they matched these scores against the number of deaths and injuries recorded in two major global databases: the Sendai Framework Monitor, which relies on official government reports, and the Emergency Events Database, which compiles information from news reports, the United Nations, and other organizations. The study covered the period from 2015 to 2023, a time that included the global pandemic, allowing the team to see how these systems held up during a period of intense, overlapping crises.

The results revealed a pattern that was significant only in the most recent years of the study. When the researchers looked at the data from 2020 through 2023, they found that countries with stronger health capacities had significantly fewer deaths. Specifically, for every ten-point increase in a country's health preparedness score, the rate of disaster-related deaths dropped by nearly forty percent. This finding held true across both databases for the aggregate model, suggesting that the connection is real and not just a fluke of how one organization counts the data. However, this association was not statistically significant when looking at the full period from 2015 to 2023. The study also found that this benefit was not limited to just one type of skill. In the years when the world was dealing with the pandemic alongside other disasters, having strong laboratory systems was particularly important for saving lives. Countries with better labs, better staffing, and stronger border health checks saw fewer fatalities, though the link between specific skills and lower mortality varied depending on the database and statistical model used.

However, the story was a bit more complicated when looking at the number of people who were injured or fell ill, rather than those who died. While the overall health score was linked to fewer injuries in the government reports from 2015 to 2023, this link disappeared when the researchers looked at the data from 2020 to 2023 or when they used the other database. One specific skill stood out as consistently helpful for reducing injuries: the ability to coordinate different groups during a crisis. Countries that were good at getting their agencies to work together saw fewer people get hurt. But for other skills, the results were mixed. In some cases, countries with better surveillance or more health workers actually reported more injuries. The researchers suggest this might not mean that better health systems cause more harm. Instead, it could mean that countries with stronger systems are simply better at finding and counting the injured, whereas countries with weaker systems might miss many of the people who need help.

The study also highlighted a crucial difference between how different countries report their data. The two databases they used often told very different stories about the same events. For example, one database reported a median of thirty-two injured people per country per year, while the other reported only two. This huge gap suggests that counting injuries is much harder and less consistent than counting deaths. Because of this, the researchers could not be as certain about the link between health skills and injuries as they were about the link to deaths. They noted that their study design, which looked at whole countries rather than individual people, could not prove that the health skills directly caused the lower death rates. It is possible that wealthier countries, which can afford better health systems, also have better roads and buildings that naturally save lives. Yet, even after adjusting for wealth and population density, the link between strong health capacities and fewer deaths remained strong in the later period.

Ultimately, this research provides the first global evidence that the health systems built to fight disease are also vital for surviving natural and technological disasters, particularly during periods of overlapping crises. The findings support the idea that the skills needed to manage a pandemic—like having a coordinated response, a ready workforce, and reliable laboratories—are the same skills needed to handle a flood or an earthquake. The study suggests that when countries invest in these cross-cutting health capacities, they are not just preparing for the next virus; they are building a foundation that saves lives when the ground shakes or the waters rise. The data indicates that a country with a robust health system is a more resilient country, capable of weathering the storm with fewer lives lost. This insight offers a clear path forward for global policy: strengthening health security is not just a medical goal, but a fundamental part of disaster preparedness.