What is Disease X? How a vaccine for an ‘unknown unknown’ virus is being developed at Porton Down

Scientists are preparing for a potential bird flu pandemic in humans, with several pharmaceutical companies already at advanced stages of developing vaccines to protect global populations against a future outbreak.

Experts at the government’s top-secret laboratories in Porton Down are preparing to test the effectiveness of avian influenza jabs for humans developed by AstraZeneca, Moderna and other firms.

Its scientists are also gearing up for a possible outbreak of so-called “Disease X”, the “unknown unknown” of viruses which could emerge from nowhere and for which there is currently no vaccine or treatment.

Here’s what we know about the research to ward off the virus.

What is Disease X?

Disease X is the name given to any as-yet-unknown pathogen which in theory has the potential to cause a global pandemic.

Dr Jenny Harris, the chief executive of the UK Health Security Agency, says scientists “will never know 100 per cent” what Disease X will be, “but we can get ready for some virus families”.

It is likely to be zoonotic, says the WHO, which means it is expected to be transmitted from animals and the pool from which it could originate is “large but limited”.

The WHO estimates there are 631,000 to 827,000 unknown viruses that have the capacity to infect human beings.

What are the chances of an outbreak?

Last week, the government’s new National Risk Register warned there is an up to one in four chance of a new pandemic, caused by any virus or pathogen, emerging in the next five years.

The government said that avian influenza was detected in cat food in South Korea. There have only been a handful of cases since the virus emerged, but scientists said the alarming rise in animals posed a risk.

The chances of a new global pandemic are also growing because of a warmer climate.

“The health effects of climate change are already being felt,” said UK chief scientific officer, Dr Isabel Oliver, adding, “we are already seeing a change in the distribution for example vector-borne viruses, those viruses which are carried by mosquitos and by ticks.”

What are scientists doing to stop Disease X?

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A global team of 300 scientists convened by the WHO is working to come up with protection against Disease X.

Professor Oliver said the UK was “absolutely” better prepared than for Covid, but added: “However, it should not be taken for granted.

“What is difficult to know is the impact they are going to have, because until we are able to characterise and know the severity of the infection or how transmissible they are, it is difficult to know and understand.”

The global “100 days mission”, launched at the UK’s presidency of the G7 in 2021, is designed to create a vaccine ready to go into people’s arms within 100 days of a new pandemic threat being identified.

Scientists said that the development of prototype vaccines at Porton Down would mean that the UK would be better prepared to stop something escalating into a pandemic, even if it were “Disease X”.