THE NEXT DEVASTATING PLAGUE, PLAGUE X OR “DISEASE X” IS ON ITS WAY AND IT COULD BE FAR WORSE THAN THE CORONAVIRUS PLAGUE KILLING MORE PEOPLE according to the World Health Organization and other scientists and doctors.

Let me remind you of the state we were in by May 2020. The outlook was unremittingly bleak: infections and deaths were mounting inexorably and hospitals were at breaking-point. The pandemic had ruptured economic activity more than any recession.

Mass vaccination was the only credible solution, but no human coronavirus vaccine had ever been approved, let alone one for Covid-19. Worse, the historic success rate for any new vaccines, from lab to jab, was a deeply depressing 10 per cent. So the scale of the challenge was stupendous.

It was in May that the then Health Secretary Matt Hancock phoned me out of the blue, asking me to become head of the new Vaccine Taskforce. I immediately took leave of absence from my job of nearly 30 years as a biotech venture capitalist — dealing with the development of new drugs — to work on finding a portfolio of vaccines, in the hope that at least one would be effective.

While scientists around the world threw themselves into developing possible vaccines at what seemed like warp speed, the taskforce worked around the clock to prioritise the best candidates at early stages, to check they were both safe and effective, to make binding deals in the face of international competition and to ensure the vaccines could be manufactured at scale.

We all know what happened a few months later: two of the taskforce’s chosen vaccines were approved by regulators. And, in December 2020, the UK became the first country in the world to launch its vaccination programme.

Believe me, none of that was inevitable. Nor should we be complacent now that Covid-19 is largely regarded as a routine illness, even though it can still kill the vulnerable and elderly.

Scientists know that it could still mutate into new variants that are more infectious and even better at evading our immune systems. What this means is that we could soon face new viral mutants resistant to all the antiviral drugs and vaccines we’ve managed to develop so far.

But even mutated variants of Covid-19 pale in comparison to the other viral threats out there.

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.

The whole point of a virus is to replicate as many times as possible in as many hosts as possible. So they are continually mutating and latching on to different animals.

In fact, some of the most dangerous viruses — such as smallpox, measles, Ebola and HIV — originated in animals and later became highly transmissible between humans.

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.

So far, scientists are aware of 25 virus families, each of them comprising hundreds or thousands of different viruses, any of which could evolve to cause a pandemic.

Worse still, they estimate there could be more than one million undiscovered viruses which may be able to jump from one species to another, mutate dramatically and kill millions of human beings.

Why were we so surprised when Covid-19 struck in 2020? It wasn’t as if we were being attacked out of the blue — say, by a giant asteroid or aliens from another planet.

In fact, the warning shots had already been fired. We knew that Covid — or something like it — was likely to arrive sooner rather than later because the pace of pandemics had been quickening over the past few decades.

Unlike an epidemic, which is contained in a single country or region, a pandemic spreads across many countries and even continents. Covid-19 was actually the seventh outbreak of a pandemic since the millenium.

It had been preceded by SARS in 2002–4, H5N1 bird flu in 2004, H1N1 swine flu in 2009, MERS in 2012, Ebola in 2014–16 and Zika in 2015–16.

What stopped these outbreaks wreaking global havoc was usually one or more of these factors: poor infectivity (MERS), a relatively low fatality rate (swine flu) or a swift, co-ordinated international response (SARS). In other words, good luck and good preparation working in tandem.

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.