- Throughout history, nothing has killed more human beings than infectious disease. Covid-19 shows how vulnerable we remain – and how we can avoid similar pandemics in the future.
- The novel coronavirus pandemic, known as Covid-19, could not have been more predictable. From my own reporting, I knew this first-hand. In October 2019, I attended a simulation involving a fictional pandemic, caused by a novel coronavirus, that killed 65 million people, and in the spring of 2017 I wrote a feature story for TIME magazine on the subject. The magazine cover read: “Warning: the world is not ready for another pandemic”.
There was little special about my insight. Over the past 15 years, there has been no shortage of articles and white papers issuing dire warnings that a global pandemic involving a new respiratory disease was only a matter of time. On BBC Future in 2018, we reported that experts believed a flu pandemic was only a matter of time and that there could be millions of undiscovered viruses in the world, with one expert telling us, “I think the chances that the next pandemic will be caused by a novel virus are quite good.” In 2019, US President Donald Trump’s Department of Health and Human Services carried out a pandemic exercise named “Crimson Contagion”, which imagined a flu pandemic starting in China and spreading around the world. The simulation predicted that 586,000 people would die in the US alone. If the most pessimistic estimates about Covid-19 come true, the far better named “Crimson Contagion” will seem like a day in the park.
As of 26 March, there were more than 470,000 confirmed cases of Covid-19 around the world and more than 20,000 deaths, touching every continent save Antarctica. This was a pandemic, in reality, well before the World Health Organization finally declared it one on 11 March. And we should have seen it coming.
Covid-19 marks the return of a very old – and familiar – enemy. Throughout history, nothing has killed more human beings than the viruses, bacteria and parasites that cause disease. Not natural disasters like earthquakes or volcanoes. Not war – not even close.
Mass killers
Take the mosquito-borne disease malaria. It has stalked humanity for thousands of years, and while death tolls have dropped significantly over the past 20 years, it still snuffs out nearly half a million people every year.
Over the millennia, epidemics, in particular, have been mass killers on a scale we can’t begin to imagine today – even in the time of the coronavirus.
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Some 50 to 100 million people died in the 1918 influenza pandemic – numbers that surpass the death toll of World War One, which was being fought at the same time. The 1918 flu virus infected one in every three people on the planet. (Read more about how the 1918 flu changed the world). HIV, a pandemic that is still with us and still lacks a vaccine, has killed an estimated 32 million people and infected 75 million, with more added every day.
Mass killers
Take the mosquito-borne disease malaria. It has stalked humanity for thousands of years, and while death tolls have dropped significantly over the past 20 years, it still snuffs out nearly half a million people every year.
Over the millennia, epidemics, in particular, have been mass killers on a scale we can’t begin to imagine today – even in the time of the coronavirus.
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Some 50 to 100 million people died in the 1918 influenza pandemic – numbers that surpass the death toll of World War One, which was being fought at the same time. The 1918 flu virus infected one in every three people on the planet. (Read more about how the 1918 flu changed the world). HIV, a pandemic that is still with us and still lacks a vaccine, has killed an estimated 32 million people and infected 75 million, with more added every day.
If these numbers shock, it’s because today epidemics are rarely discussed in history classes, while in the not so distant past, they were simply a terrible fact of life. There are few memorials to the victims of disease. The historian Alfred Crosby was the author of America’s Forgotten Pandemic, one of the great books on the 1918 flu. But Crosby was only prompted to begin researching the pandemic when he stumbled on the forgotten fact that American life expectancy had suddenly dropped from 51 years in 1917 to 39 years in 1918, before rebounding the following year. That plummet in 1918 was because of a virus just 120 nanometers wide.
Viral advantage
Pathogens make such effective mass killers because they are self-replicating. This sets them apart from other major threats to humanity. Each bullet that kills in a war must be fired and must find its target. Most natural disasters are constrained by area: an earthquake that strikes in China can’t directly hurt you in the UK.
But when a virus – like the novel coronavirus – infects a host, that host becomes a cellular factory to manufacture more viruses. Bacteria, meanwhile, are capable of replicating on their own in the right environment.
The symptoms created by an infectious pathogen – such as sneezing, coughing or bleeding – put it in a position to spread to the next host, and the next, a contagiousness captured in the replication number, or “R0” of a pathogen, or how many susceptible people one sick person can infect. (Imperial College London has estimated the novel coronavirus’s R0 at 1.5 to 3.5.) And because human beings move around – interacting with other human beings as they do so in every manner from a handshake to sexual intercourse – they move the microbes with them. (Read more about what makes viruses so difficult to outsmart).
No wonder militaries have long tried to harness disease as a tool of war. No wonder that, until recently, far more soldiers died of disease than died in combat. A pathogen is a perfectly economical weapon, turning its victims into its delivery system.
Viral advantage
Pathogens make such effective mass killers because they are self-replicating. This sets them apart from other major threats to humanity. Each bullet that kills in a war must be fired and must find its target. Most natural disasters are constrained by area: an earthquake that strikes in China can’t directly hurt you in the UK.
But when a virus – like the novel coronavirus – infects a host, that host becomes a cellular factory to manufacture more viruses. Bacteria, meanwhile, are capable of replicating on their own in the right environment.
The symptoms created by an infectious pathogen – such as sneezing, coughing or bleeding – put it in a position to spread to the next host, and the next, a contagiousness captured in the replication number, or “R0” of a pathogen, or how many susceptible people one sick person can infect. (Imperial College London has estimated the novel coronavirus’s R0 at 1.5 to 3.5.) And because human beings move around – interacting with other human beings as they do so in every manner from a handshake to sexual intercourse – they move the microbes with them. (Read more about what makes viruses so difficult to outsmart).
No wonder militaries have long tried to harness disease as a tool of war. No wonder that, until recently, far more soldiers died of disease than died in combat. A pathogen is a perfectly economical weapon, turning its victims into its delivery system.