Yes, almost certainly. The question isn’t whether another pandemic will happen but when. A 2021 analysis published in the Proceedings of the National Academy of Sciences estimated that the probability of experiencing a pandemic on the scale of COVID-19 within any person’s lifetime is roughly 38%, and that figure may double in the coming decades as the conditions that spark outbreaks continue to worsen.
That doesn’t mean one is imminent. It means the baseline risk is higher than most people assume, and it’s rising. Here’s what’s driving that risk, what threats scientists are watching most closely, and what the world is doing differently since 2020.
How Often Major Pandemics Occur
Researchers built a dataset of large epidemics spanning from 1600 to the present and found that the probability of extreme outbreaks follows a pattern: they decrease slowly with intensity, meaning very large pandemics are rare but not as rare as you might hope. A Spanish flu-scale event, which killed tens of millions, has a mean recurrence time of about 879 years at today’s rates. But that number is a moving target. The same study found that a tripling of the rate at which new diseases jump from animals to humans, an increase consistent with trends already being observed, would shrink that recurrence interval to roughly 292 years.
For less extreme but still devastating pandemics like COVID-19, the math is more sobering. The yearly probability is already high enough that the chance of living through one is better than a coin flip over a full lifetime, and environmental pressures are pushing those odds higher with each passing decade.
Why the Risk Keeps Growing
Most pandemics begin with a virus jumping from an animal to a human. The rate of these spillover events is accelerating for reasons that are largely tied to how humans are reshaping the planet.
Deforestation removes the habitats where wildlife normally lives, pushing animals into closer contact with people. When forests are cleared, the loss of canopy cover also creates standing water and sunlight conditions that are ideal for mosquito breeding, expanding the range of insect-borne diseases. Urbanization has a similar effect from the other direction: as cities expand into previously wild areas, animals are drawn toward human settlements for food and shelter, creating new opportunities for viruses to cross species.
Wildlife trade compounds the problem. When animals from different species and different continents are packed together in cramped, unsanitary conditions during transport and sale, the chances of cross-species viral transmission rise sharply. Climate change layers on top of all of this by altering the range and activity of disease-carrying insects. Warmer temperatures let mosquitoes and ticks survive in regions that were previously too cold, extending transmission seasons and exposing new populations.
None of these trends are slowing down. That’s the core reason epidemiologists expect the frequency of outbreaks to increase.
The Threats Scientists Watch Most Closely
Influenza remains the single most likely source of a future pandemic. The H5N1 strain of bird flu has been circulating in poultry and wild birds for years and has recently spread into dairy cattle in the United States. The CDC continues to assess the current H5N1 risk to the general public as low, but people who work with or around infected animals face elevated risk, particularly without protective equipment. What concerns virologists is the possibility that H5N1 could acquire mutations allowing efficient human-to-human transmission. If that happens, the virus would have a head start: it’s already widespread in animal populations worldwide.
Coronaviruses are another obvious concern. COVID-19 was the third major coronavirus outbreak in two decades, following SARS in 2003 and MERS in 2012. The family of viruses is large, diverse, and circulates heavily in bat populations, making future spillovers likely.
A less discussed but increasingly serious threat comes from antibiotic-resistant bacteria. The WHO maintains a priority list of 24 bacterial pathogens across 15 families that are developing resistance to existing drugs, including bacteria resistant to last-resort antibiotics. Antimicrobial resistance doesn’t spread the same way a respiratory virus does, but it could turn a manageable outbreak into a far deadlier one by eliminating the ability to treat secondary infections. In that scenario, death rates would revert to what they looked like before antibiotics existed.
How Preparedness Has Changed Since COVID-19
The world learned some expensive lessons from 2020, and several systems are now in place that didn’t exist before.
Wastewater surveillance is one of the most tangible advances. By testing sewage for traces of pathogens, public health agencies can detect rising infection trends an average of four to six days before clinical testing data shows the same changes. That lead time matters enormously for triggering early interventions. The CDC and counterparts in other countries have built national wastewater monitoring networks that now track not just COVID-19 but other pathogens as well.
On the vaccine front, the Coalition for Epidemic Preparedness Innovations (CEPI) launched what it calls the 100 Days Mission: developing and making available a new vaccine against a novel pathogen within 100 days of that threat being recognized. That’s roughly a third of the time it took to deliver the first COVID-19 vaccines. The initiative focuses on three pillars: speeding up the initial development process, building enough manufacturing capacity to eliminate supply bottlenecks, and strengthening health systems so vaccines can be distributed equitably once they exist.
Whether that 100-day target is achievable in practice remains to be tested. But the underlying platform technologies, particularly mRNA vaccines, are genuinely faster to design and produce than traditional approaches. The infrastructure built during COVID-19 gives the world a significant advantage it didn’t have before.
The New International Pandemic Agreement
In May 2025, the World Health Assembly adopted a new international Pandemic Agreement after years of negotiation. The agreement sets out principles for international coordination on prevention, preparedness, and response, with a strong focus on equitable access to vaccines, treatments, and diagnostics.
One of its most concrete provisions involves pharmaceutical manufacturers. Companies participating in the agreement’s access system would commit to making 20% of their real-time production of pandemic-related health products available to the WHO for distribution based on public health need, with priority given to developing countries. The agreement also calls for a new global supply chain network designed to reduce the bottlenecks that left many countries waiting months for vaccines during COVID-19.
The agreement explicitly states that it does not give the WHO authority to direct national policy, mandate vaccinations, or impose lockdowns. Those decisions remain with individual governments. The agreement needs 60 countries to ratify it before it takes effect, a process that will take time as national legislatures review the text.
The Funding Gap
Preparedness costs money, and the world isn’t spending enough. An independent panel estimated that development partners should invest an additional $15 billion annually, while national governments should dedicate an extra 1% of GDP toward health infrastructure, including the surveillance tools needed to catch outbreaks early. Separate estimates put the total need at about $26.4 billion at the national level and $4.7 billion at the global level each year.
Those numbers sound large, but they’re small relative to the cost of an actual pandemic. COVID-19 caused trillions of dollars in economic damage globally. The investment gap in preparedness represents a fraction of what the next pandemic would cost if it catches the world off guard again. Whether governments maintain their commitment to pandemic preparedness as the memory of COVID-19 fades is one of the biggest variables in how the next outbreak plays out.