Have We Learned The Right Lessons To Deal With The Next Pandemic? Disease X Is Coming Sooner Or Later

Some argue that the large-scale conversion of deforested land into agricultural fields raised the chances of bat-human interactions. 

The idea here is that a mutated version of the infection made it easier for the virus to cross the species divide, a process known as zoonotic spillover, as more people came into contact with the winged host. 

Others suggest the disease moved from bats into domestic animals, livestock, or rodents on the new farmland or in local towns, offering even more chances for it to pass onto humans.

In either case, once the infection spread to people it likely underwent another mutation allowing it to infect our cells more easily. From here, it started transmitting through a small population. 

At first, there were only a few isolated cases. The infection presented with flu-like symptoms, so was easily overlooked or misdiagnosed as common respiratory illnesses. But while some people presented with mild symptoms, others developed severe complications requiring hospital care. 

This brought the disease to the medical community’s attention, but even while they became more suspicious, it was still not clear whether they were facing a new pathogen or simply a variation of one they already knew.

This gap was significant. The variation in symptoms made the outbreak difficult to detect and so cases could easily slip by unnoticed. Its major mode of transmission – coughs and sneezes – also allowed it to spread quickly as it moved into increasingly dense communities. 

It helped that there was also a long incubation period between initial infection and the onset of obvious symptoms. This made it a silent danger, passing on to people who could carry it farther and farther away from its forest origins. 

Eventually, the new disease reached a large cosmopolitan city where cars, trains, and planes let it travel from country-to-country and continent-to-continent.

Sure, local authorities attempted to contain the outbreak. They forced infected people to isolate and they traced contacts, but by the time these measures were fully implemented, the infection had already broken beyond the country’s confines. 

It was now a global threat, and because humans have no immunity to this new virus, it experienced little trouble in its new international contexts. In fact, our reliance on fast-paced, extensive transport networks that connect densely populated environments is not just convenient for our modern lives – it's also ideal for propelling the virus onwards.

In these new countries, early case numbers were uncertain, as everyday people in developed nations did not expect to suffer an illness from another part of the world. Cases were underreported and national surveillance systems established to catch this type of outbreak took time to respond. It didn’t help that many of these systems were grossly underfunded. 

Then, as reports of a new disease spread, so too did uncertainty. Information was confusing. Although people were talking about the infection, it was difficult to discern between correct and useful information and distortions or outright disinformation, as what was a biological problem became embroiled in human politics.

And yet the disease spread. 

Hospitals were soon overrun, staff were exhausted, and the supply of oxygen and ventilators quickly ran out. Travel bans were initiated, testing centers were set and a new contact tracing mechanism was installed to track the disease. 

While scientists raced to decode the virus’s genome so they could develop a vaccine, the economy faltered, supply chains stalled, and within a few months hundreds of thousands of people had died across the world.

Does this sound familiar? Although it may look like I just articulated the process whereby COVID-19 emerged onto the world stage, I am not actually describing that disease’s story. 

Instead, this hypothetical narrative explains the emergence of another virus that we have yet to encounter, one that presents itself to the world in similar ways. 

Scientists refer to this hypothetical future infection as Disease X (sometimes Pathogen X). And there’s one important thing we need to understand about this disease: although we don’t know what it will be, we know it is coming. It is just a matter of time.

Gray rhinos

The World Health Organization (WHO) introduced the concept back in 2018 as a way to prepare for a future unknown pathogen that could become an international pandemic. 

Sometimes described as a “gray rhino” event, Disease X represents something people can see coming, recognize as extremely dangerous and yet ultimately ignore until it starts to charge. 

In this instance, Disease X is intimately connected to other slow-moving threats, such as climate change, which promise catastrophic challenges for human health and wellbeing if they’re not taken seriously.

Ultimately, Disease X is meant to ignite the need for long-term planning and pandemic preparedness. It functions as a placeholder for an unknown future pathogen, one that could emerge and pose a serious global threat – be it a novel virus, a lab-based accident, or even a defrosted ancient variant.

For many people, if they have heard of Disease X, it’s likely because of the COVID-19 pandemic, which shut down much of the world in 2020 – but as noted above, the concept predates this event. 

In many ways, COVID-19 can be seen as a proof-of-concept for Disease X: it was a fast-moving variation of a known virus that quickly highlighted how insufficient nations were at detecting, tackling, and responding to it in real time.

So, Disease X is not simply about a specific pathogen, but rather the persistent gap between recognizing the possibility of new diseases and establishing dynamic systems to respond to them despite the uncertainties. 

The question is then, are we now in a better place for when the unknown but highly anticipated next infection arrives? Because it will come. This is not an attempt at fear-mongering; the likelihood of another COVID-19-like spillover is actually rising. It is even possible that the next pandemic-causing microorganism is already out there, quietly mutating.

Since the turn of the century, we have already seen the emergence of multiple novel or re-emerging viruses. They include SARS-CoV-1, MERS, and Zika, among others. 

In 2022, researchers observing the long history of infectious diseases found that the chance of another similar pandemic is around 1 in 50 in any year. This basically means that people have a 38 percent chance of experiencing a pandemic across their lifetime. 

But this is based on the current situation. The study warns that this probability may double in the coming decades as climate and environmental change makes the chances of a spillover event more likely.

Lessons learnt

Since the last pandemic, governments, research institutes, and international organizations have launched a range of projects and initiatives designed to prepare for Disease X. 

For instance, in 2015, the WHO created a comprehensive global strategy that centered on its “pathogen priority list”, which concentrated research efforts on pathogens with pandemic potential and where medical countermeasures were limited or missing entirely. 

Then, in 2022, they adopted a new approach where they focused on entire classes of viruses or bacteria, rather than single pathogens.

The benefit of this family-focused approach is that it lets researchers develop vaccines, tests, and treatments for whole classes of disease agents, rather than reacting to them one at a time (which is slow and expensive). 

It also lets them identify representative viruses within a viral family that can function as “pathfinders” for addressing knowledge gaps that could relate to other, more threatening viruses from the same family.

In this sense, the WHO and scientists involved in this approach are trying to create universal tools that can be applied to any threat that appears in a specific family.

Advances in diagnostic technologies and new methodologies are allowing researchers to profile known and unknown pathogens in the wild. This is significant because even though we may know a specific pathogen exists, it is not always easy – or safe – to physically collect them in the field. 

But new non-invasive techniques, such as polymerase chain reaction (PCR) tests (the types of tests we took during the COVID-19 pandemic), can be used directly on animals as well as saliva found on their discarded food. 

At the same time, there have been developments in multiplex serological assays, which can be used to assess whether animals have antibodies for specific pathogens. This type of evidence helps scientists determine whether the animals have already encountered a given disease in the past.

This is particularly important given how Disease X will likely come from another zoonotic spillover event (though researchers are also preparing for potential accidental release from labs). As climate change and human activity continue to change the environment, humans and disease-carrying animals are more likely to interact, and probably in ways that we are not used to. 

As such, another way that scientists are preparing for Disease X is to model how human-animal interactions will likely develop in the future. These models are not limited to human interactions with wild animals, but also their pets.

In 2025, scientists at Washington State University developed machine learning models that can analyze host characteristics and virus genetics to identify potential animal reservoirs, as well as their geographic distribution. 

The model identified Southeast Asia, equatorial Africa, and the Amazon as potential hotspots for spillovers of orthopoxviruses – a genus of viruses that cause raised, bumpy rashes. These regions, the researchers note, have a high concentration of potential virus hosts, but are also in places where smallpox vaccination coverage is low (smallpox was also an orthopoxvirus).

The global surveillance of diseases in wildlife, domestic animals, and pets is a priority for preparing for Disease X. But surveillance is only part of the challenge. If a new disease is detected, we need to know that we have robust healthcare systems ready to deal with any potential widescale spread. 

This is the frontline of defense against pandemics, especially in countries that lack the resources to prevent transmission. Staff need detailed biosecurity training to prepare for future events, while hospitals in dense urban centers need to be equipped with specialized isolation centers for infected individuals.

Fangcang shelters may be one way to achieve this. These novel public health structures were created in China during the last pandemic to temporarily support hospitals. They can be quickly built and at sufficient scale in existing public spaces, such as stadiums or exhibition centers.

In addition to these and other improvements to health systems, we vitally need new ways to rapidly develop vaccines and antiviral drugs. COVID-19 demonstrated just how unprepared we were to develop vaccines quickly under emergency conditions, even though the development of COVID vaccines was itself a fast achievement. But in this instance, scientists already had years of research to draw on.

Since 2017, the Coalition for Epidemic Preparedness Innovations (CEPI), an international partnership, has been pushing efforts to develop safe and effective vaccines against novel viral threats to just 100 days. In most cases, this involves solving many of the challenges that slow up vaccine development in advance. 

One way to do this is to develop vaccines against prototypes of viral families – ones that exemplify some or all of the bad traits of a viral family. By eliminating the challenges associated with developing a vaccine for that family, it becomes easier to make a targeted vaccine if a member of that family becomes a threat in the future.

From here, they can create a candidate vaccine library for each viral family. So, when Disease X appears, they can choose the best candidates for rigorous testing, including for their safety and dosing trials for people. 

CEPI are coupling this with the development of better non-pharmaceutical interventions, including testing, contact tracing and social distancing measures – and enhanced surveillance methods to serve as early warning systems for new diseases. 

If successful, when Disease X arrives, we will be able to respond far quicker than we did in 2020, which could save millions of lives and limit economic costs.

Are we ready?

This may all sound inspiring. It may sound like there are answers to the problems we faced during the last pandemic, but is that the case? 

Disease X, as a concept, certainly provides scientists with a way to prepare for another outbreak, but that alone is not enough. Any disease that emerges is only partially a scientific problem. It is also a political one, and without sustained political and societal support, preparations for Disease X will be limited.

Since COVID-19, governments around the world have become more keenly aware of the situation, but this needs to be translated into meaningful support. Many countries are still struggling to provide sustained investment in public health measures or systems designed to limit the impacts of another pandemic. 

As Dr Tedros Adhanom Ghebreyesus, WHO Director-General, explained in March 2025, “Fragile supply chains, inequitable access to life-saving tools and the spread of mis- and dis-information remain serious problems.”

At the same time, the COVID-19 pandemic demonstrated just how connected our world has become, and how we need global solutions for these challenges. 

It is not sufficient that developed countries simply manufacture vaccines for their own populations while those in developing countries are left waiting. The more chances a virus has to spread, the more of a challenge it becomes. 

More recently, Ghebreyesus and Luiz Inácio Lula da Silva, Brazil’s president, urged the G7 nations to solidify their commitments to protect lives by creating a new treaty for sharing information and access to vaccines, tests, and treatments.

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Developing nations worry that future pandemics will present the same problems that COVID revealed. That is, that pharmaceutical companies sidelined some nations that contributed data for new vaccines. 

This was not necessarily a deliberate move, but one that highlighted existing international inequalities whereby developed nations preordered and stocked up on newly manufactured vaccines, forcing developing nations to wait. 

Vaccine nationalism – where wealthy nations secured exclusive bilateral agreements with pharmaceutical companies to gain early access to vaccine – also contributed to this problem.

In response, pharmaceutical representatives have warned that a mandatory requirement to share resources will stifle research and development. This sentiment is not overly valid. A significant share of the foundational basic science that creates new drugs and vaccines comes from government investment and public institutions who absorb much of the early development losses. 

As such, the argument that industry will be stifled doesn’t hold much water.

Nevertheless, overcoming the barriers presented by pharmaceutical agencies remains an important political hurdle facing the development of the WHO’s pandemic treaty. 

Then there’s the need to maintain the political will to prepare for these events. Since coming into office in 2025, the Trump administration has severely undermined years of scientific and institutional efforts to monitor diseases, trace their development, and to generate new vaccines. 

Well over $1 billion in drug and vaccine development investments have been lost, while a similar amount in anticipated funding remains unassigned.

These cuts have effectively disarmed the US’s ability to response to natural outbreaks but also makes them vulnerable to bioweapons if they were to be used by a malicious entity.

But preparations for the next pandemic do not rest with governments alone. Communities at all levels need to be ready to respond when the next infection appears. Throughout COVID-19, mis- and disinformation made it difficult to coordinate effective responses, leading some individuals to reject confinement measures or to avoid vaccines. 

Although trust in science is recovering, there are still gaps where disinformation remains entrenched in people’s minds.

There is also a palpable desire among the public to simply forget the trauma they experienced during the pandemic. This phenomenon, known as “mnemonic silence” has global reach and is a reaction to mass fatigue, feeling overloaded by information, and a desire to protect ourselves from the psychological stress we endured at the time. 

This results in a kind of collective amnesia, but one that risks forgetting the key lessons that were learned.

So, whether we are ready for Disease X remains unclear. We have certainly identified the lessons from previous outbreaks, but it is a question of whether we can act on them in meaningful ways.