Scientists have revealed fears surrounding the next pandemic that is 'already on the way' and believe we got off lightly with COVID-19.

Disease X - as it has been dubbed by the World Health Organisation (WHO) - is a probability rather than a possibility and could hit at any moment.

It could come from a million undiscovered viruses and it could kill 50 million people globally, 20 times more deadly than coronavirus, which caused 2.5million deaths.

The next pandemic could be on a similar scale to the Spanish flu. From 1918 to 1919, the Spanish flu infected an estimated 500 million people globally and killed 10% of those infected.

WHO believes vaccines will need to be created and delivered in a rapid response to combat the disease.

It adds that its devastating effects are likely to far outweigh that of Covid, which the world was dangerously unprepared for when it hit in early 2020.

Kate Bingham, who chaired the UK's Vaccine Taskforce between May and December of that year says we shouldn't be complacent just because Covid-19 is now "largely regarded as a routine illness".

The 57-year-old Dame warned in the Mail: "Let me put it this way: the 1918–19 flu pandemic killed at least 50 million people worldwide, twice as many as were killed in World War I.

"Today, we could expect a similar death toll from one of the many viruses that already exist. Today, there are more viruses busily replicating and mutating than all the other life forms on our planet combined. Not all of them pose a threat to humans, of course - but plenty do."

"In a sense, we got lucky with COVID-19"

She revealed that scientists are currently aware of 25 virus families, which each comprise up to thousands of individual viruses that all have the potential to evolve into a pandemic.

On top of that, it is estimated that there could be around a million more undiscovered viruses lingering out there which could leap from species to species and have the capability of killing millions of human beings.

She continued: "In a sense, we got lucky with COVID-19, despite the fact that it caused 20 million or more deaths across the world.

"The point is that the vast majority of people infected with the virus managed to recover. Imagine Disease X is as infectious as measles with the fatality rate of Ebola [67%]. Somewhere in the world, it’s replicating, and sooner or later, somebody will start feeling sick.

"We need to take the first steps in dealing with the next pandemic right now — and that involves putting money on the table. Yet there’s very little evidence that we’re prepared to spend anything remotely comparable on protecting ourselves from real viruses - the ones that could kill us.

"The monetary cost of inaction is seismic. After all, even Covid-19 - a milder virus than Disease X - managed to leave us holding a bill for $16 trillion in both lost output and public health expenditure."

Kate said it is crucial that we discover a collection of "different prototype vaccines for every threatening virus family" that we know of before the next pandemic begins.

"With that "head start" vaccines could be engineered to "target the very specific features of Disease X", which thankfully is "not impossible at all".