Preventing a pandemic requires action on multiple fronts simultaneously: stopping new diseases from jumping from animals to humans, detecting outbreaks early enough to contain them, and building the infrastructure to respond within days rather than months. An estimated 75% of emerging infectious diseases originate in animals, which means the most effective prevention starts long before a virus reaches its first human host. The good news is that comprehensive prevention would cost roughly $20 billion per year globally, a fraction of the $350 billion minimum in lives lost and $212 billion in direct economic damage that emerging infectious diseases already cause annually.
Stopping Diseases at the Source
Because three out of four emerging infectious diseases jump from animals to humans, the single highest-impact strategy is reducing the opportunities for that jump to happen. This concept drives what public health experts call the One Health approach: treating human health, animal health, and environmental health as a single interconnected system rather than three separate problems. In practice, it means veterinarians, ecologists, disease detectives, and physicians working together at local, national, and global levels to monitor threats before they cross species lines.
Deforestation is one of the biggest accelerators of this risk. When forests are cleared, wildlife communities collapse in ways that favor the species most likely to carry dangerous pathogens. The remaining animals face more stress (which increases their susceptibility to infection), and the patchwork of farmland, secondary forest, and human settlement creates constant contact between wildlife, livestock, and people. Mosaic landscapes and monoculture agriculture are particularly effective at creating the conditions for spillover. Preserving intact ecosystems isn’t just an environmental goal. It’s a direct public health intervention.
Livestock management matters too. Concentrated animal farming operations, live animal markets, and the wildlife trade all create mixing zones where viruses can adapt to new hosts. Stronger regulation of these interfaces, better veterinary surveillance in farming communities, and reducing unnecessary contact between wild and domestic animals are practical steps that lower spillover risk at the source.
Detecting Threats Early
When a new pathogen does emerge, the window between first detection and widespread transmission determines whether it becomes a local outbreak or a global crisis. The World Health Organization’s International Pathogen Surveillance Network (IPSN) was created to close gaps in that window. The network connects countries to share genomic sequencing data, the process of reading a pathogen’s genetic code to understand what it is, how it’s evolving, and how it spreads. This kind of surveillance proved essential during COVID-19, when genomic tracking allowed scientists to identify new variants and predict their behavior.
The vision behind the network is that every country, not just wealthy ones, should have the capacity to sequence pathogen genomes and feed that data into a shared global system. Right now, that capacity is unevenly distributed. Many low- and middle-income countries lack the labs, trained personnel, and funding to participate fully, which creates blind spots in the global surveillance picture. Investing in regional diagnostic networks and training local workforces is one of the most concrete steps toward closing those gaps.
Rapid diagnostic tests are equally critical. During COVID-19, test shortages slowed the response because too few manufacturers were producing them. The goal for future outbreaks is to have accurate, point-of-care diagnostic tests ready to scale within the first 100 days of recognizing a new threat. That requires pre-positioned manufacturing capacity, stockpiled raw materials, and distribution systems that can reach remote areas quickly.
Building Vaccine and Treatment Infrastructure
The development of COVID-19 vaccines in under a year was unprecedented, but it still wasn’t fast enough to prevent millions of deaths. The 100 Days Mission, a framework endorsed by international health leaders, sets the goal of having vaccines authorized and manufactured at scale within 100 days of identifying a pathogen with pandemic potential. Five technical pillars support that timeline:
- Prototype vaccines developed in advance for representative viruses across the major viral families most likely to cause pandemics
- Immune response markers that can quickly tell researchers whether a vaccine candidate is working
- Pathogen characterization capabilities to understand a new virus’s structure and vulnerabilities within days
- Rapid manufacturing platforms that can switch from prototype to full production without starting from scratch
- Pre-built clinical trial networks with sites, protocols, and regulatory agreements already in place, ready to activate immediately
The mRNA vaccine technology used for COVID-19 demonstrated one version of this concept. Because the platform is adaptable, scientists could swap in the genetic sequence of a new virus without redesigning the entire vaccine. Expanding these flexible manufacturing platforms across more regions of the world is essential for ensuring vaccines reach populations equitably and quickly.
Strengthening Global Rules and Cooperation
Pandemics cross borders, so prevention depends on countries agreeing to share information and resources. The International Health Regulations (IHR), the legal framework governing how nations report and respond to health emergencies, were recently amended with significant changes that took effect in 2025. The most notable update introduces a new alert level called a “pandemic emergency,” which sits above the existing “public health emergency of international concern” designation and triggers stronger obligations for international collaboration.
The amendments also require governments to establish dedicated National IHR Authorities to coordinate implementation and include provisions for more equitable access to medical products and financing during emergencies. However, a key limitation remains: the WHO serves as the secretariat for these regulations but has no authority to compel countries to act. Compliance is ultimately voluntary, which means the system works only as well as the political will behind it.
What Travel Restrictions Can and Cannot Do
Border closures and travel bans are often the most visible response when a new disease emerges, but the evidence for their effectiveness is mixed. During COVID-19, targeted restrictions on travelers from Wuhan were temporarily effective at slowing early exportation of the virus but insufficient to stop its global spread. Studies consistently show that earlier implementation leads to higher effectiveness, but most travel restrictions, including those aimed at stopping new variants, did not meaningfully prevent introduction of the virus to new countries.
The practical takeaway is that travel measures can buy time, sometimes a few weeks, for health systems to prepare. They are not a containment strategy on their own. That bought time only matters if it’s used to ramp up testing, secure medical supplies, and activate public health responses.
Laboratory Safety as a Prevention Layer
Research on dangerous pathogens is necessary for developing vaccines and treatments, but it carries inherent risk. Laboratories that work with the most dangerous organisms operate under a tiered biosafety system ranging from BSL-1 (basic precautions for low-risk agents) to BSL-4 (maximum containment for pathogens that cause severe disease with no available treatment). Each level builds on the one below it with progressively stricter controls over lab practices, safety equipment, and facility construction.
At BSL-4, researchers wear fully encapsulating positive-pressure suits designed so that if the suit is punctured, air flows outward rather than inward. These facilities have dedicated air handling systems, chemical showers for decontamination, and multiple layers of physical barriers between the lab and the outside environment. Maintaining rigorous oversight of these facilities, ensuring consistent training, and limiting the number of labs handling the most dangerous pathogens all reduce the probability of an accidental release.
The Economics of Prevention
Perhaps the strongest argument for pandemic prevention is financial. A study led by researchers at the Harvard T.H. Chan School of Public Health, published in Science Advances, found that the annual cost of primary pandemic prevention, roughly $20 billion, is less than 5% of the minimum estimated value of lives lost to emerging infectious diseases every year and less than 10% of the direct economic costs. Those prevention dollars also generate co-benefits: protecting forests reduces carbon emissions, improving livestock management increases food security, and building surveillance capacity strengthens responses to endemic diseases that already kill millions.
The math is stark. The world loses at minimum $350 billion annually in the value of lives cut short by emerging infections, plus $212 billion in economic damage. Spending a small fraction of that on the upstream causes would represent one of the highest-return investments any government could make.