What is Disease X? How conspiracy theorists hijacked pandemic preparedness

After three years immersed in COVID-19 pandemic research, scientists worldwide are working to identify what pathogens could spur the next severe global outbreak. But this pandemic preparedness work has also been fodder for online misinformation.

At the center of the confusion is the term "Disease X," a broad phrase scientists use to describe the source of the next potential global pandemic. But conspiracy theorists have given the name a starring role in a baseless narrative.

An Aug. 7 Instagram reel described Disease X as a pandemic and suggested it was planned. Multiple posts on X, formerly Twitter, made similar claims, calling Disease X a "plandemic."

An Aug. 8 TikTok video claimed Disease X is a "money-making scam" to "lock (people) down in their homes."

Another TikTok video from the same day showed a screenshot of an article headlined "UK scientists preparing vaccines for mystery ‘Disease X.’"

"Bulls–t," the video’s caption read. "They know what’s about to be released!"

But Disease X isn’t a specific known disease. And the only thing that is being "planned" is how to respond when a known disease emerges. Efforts to mitigate future public health crises are not evidence that pandemics are planned.

Since 2020, there have been numerous conspiracy theories that the COVID-19 pandemic was planned; these have been repeatedly debunked. Claims about Disease X are similarly off-base.

Disease X refers to any disease that could potentially cause a global epidemic for which there is not yet a vaccine.

Scientists have used this term for years. In 2015, the World Health Organization first developed a list of "priority pathogens" in order to identify and prepare for diseases that could cause global outbreaks or pandemics. Since then, the WHO has continually updated the list.

The WHO’s current priority diseases are:

• COVID-19

• Crimean-Congo haemorrhagic fever

• Ebola virus disease and Marburg virus disease

• Lassa fever

• Middle East respiratory syndrome coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS)

• Nipah and henipaviral diseases

• Rift Valley fever

• Zika

• "Disease X"

According to the World Health Organization, Disease X "represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease."

Online chatter about Disease X persisted throughout the COVID-19 pandemic, but it has recently spiked following the debut of a United Kingdom research facility dedicated to the study of deadly pathogens.

On Aug. 6, the U.K.’s Health Security Agency opened a Vaccine Development and Evaluation Centre in southwest England. The facility’s more than 200 scientists are working to prepare for Disease X by assessing animal viruses that could infect humans and pathogens that do not yet have a vaccine.

The scientists are building upon the response to the COVID-19 pandemic by testing emerging vaccines against new variants. Their research will also identify areas where immunizations could be improved, such as with flu shots or mpox vaccinations.

This work is part of the "100 Days Mission," a global effort initiated by the Center for Epidemic Preparedness Innovations to make safe and effective vaccines against any potential pandemic threat within 100 days of identification. The center was launched in 2017 in Davos, Switzerland, as an international partnership between governmental, private, philanthropic and civil society organizations promoting vaccine development. It funds the 100 Days Mission, which has been backed by 18 countries, including the U.K. and the United States, and several philanthropies.

As part of pandemic preparedness efforts, scientists worldwide are working to develop "prototype vaccines" for known human diseases.

These prototype vaccines will help build a "vaccine library" that scientists can pull from and adapt quickly to create effective inoculations whenever the next Disease X is identified.

There are about 260 known viruses that infect humans, stemming from 25 virus families, the Center for Epidemic Preparedness Innovations reports. 

Within a family, viruses share certain characteristics, such as structural proteins and how they replicate their DNA, said Jane Knisely, pandemic preparedness strategy coordinator for the National Institute for Allergies and Infectious Diseases, which is part of the National Institutes of Health.

"The idea is to select representative members from each of those viral families of concern and to conduct basic research … (on) making effective vaccines for those representative or prototype viruses," Knisely said.

This research gives scientists a foundation of knowledge to draw upon should any pathogen from a virus family emerge as a pandemic threat, Knisely said.

Although it’s impossible to develop vaccines against every single potential virus, the Center for Epidemic Preparedness Innovations said priority is given to researching vaccines to fight diseases that pose the greatest public health risk.

Prototype vaccines have already been put to use. One reason the COVID-19 vaccine was developed faster than previous vaccines was that scientists had already been working on vaccines against MERS-CoV and SARS, which belong to the same virus family as COVID-19.

"If that foundational work had not been done on those viruses, it would have taken much longer to conduct the research needed to make effective vaccines (against COVID-19)," Knisely said.

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