How do pandemics end? COVID-19 could end several ways, and they're all messy
Some burn out; some fade away. Few illnesses, though, disappear altogether
This column is an instalment in our series Apocalypse Then, in which cultural historian Ainsley Hawthorn examines the issues of COVID-19 through the lens of the past.
Judging by the lack of public health restrictions you'd think COVID-19 was behind us, but the first week in November was one of Newfoundland and Labrador's deadliest since the onset of the pandemic.
With hundreds of new cases reported weekly and hundreds or even thousands more going unrecorded, it feels less like the pandemic has ended and more like we've simply decided to let it run its course.
So exactly how do pandemics end, and what can we expect in the months and years to come?
There are several paths.
The fix
The dream ending to any pandemic is an antidote — one that will stop a disease in its tracks.
Illnesses like polio, rubella and diphtheria were eliminated in North America through national vaccination efforts. Meanwhile, antibiotics, which were discovered in 1928, can cure communicable diseases like typhus, syphilis and scarlet fever.
Medical problems, though, don't always require medical solutions. Sometimes the best interventions are those that cut the chains of disease transmission in the environment.
Malaria was once widespread in the United States, thriving in the hot, humid climate of the American South and killing hundreds of thousands of Americans each year.
The Centers for Disease Control and Prevention was founded primarily to combat malaria in the country. Because there were no effective vaccines or treatments available for the disease at the time, the organization instead set its sights on exterminating the mosquitoes that spread the malaria parasite.
Instead of employing epidemiologists and microbiologists, in the 1940s and 1950s the CDC's staff was made up mostly of entomologists and engineers tasked with researching mosquitoes and developing pest control strategies.
Focusing on the bug that spread the bug paid off. By draining huge swaths of swampland and spraying millions of homes with insecticide, the CDC and its partners successfully extinguished malaria in the United States by 1951.
The burnout
Sometimes no solution for a disease presents itself, and a pandemic simply runs wild until it burns itself out.
When a new strain of influenza swept a war-torn world in 1918, it hit hard and fast, tearing through cities in a matter of weeks and leaving the population decimated. A person might wake healthy one morning and be dead the next day.
Instead of affecting mostly young children and the elderly like the seasonal flu, roughly half of those killed by the so-called Spanish flu were adults in the prime of life — men and women in their 20s and 30s.
According to historian John M. Barry, author of The Great Influenza, "as many as eight to 10 per cent of all young adults then living may have been killed by the virus."
After three or four waves over two years, the pandemic abated. Not because a cure had been found but because the virus simply ran out of people to infect. So many people had caught the flu and were immune to it by that point that it could no longer spread effectively.
That herd immunity came at a high price. An estimated 50 million people died in the pandemic, almost three per cent of the world's population at the time.
The settle-in
Though the 1918 pandemic ended, the virus that caused it never really went away. It kept mutating until it evolved into new forms different enough from the original version that they could again infect the global population.
Most of those later variants caused only mild, seasonal influenza, but several exploded into new pandemics. In fact, every flu pandemic since 1918 has been caused by a virus descended from the 1918 H1N1 strain.
Once they emerge, diseases are usually with us for good, and, unlike the flu, some pathogens never mutate into weaker forms.
Take as an example the mother of all contagions: plague itself.
To a medieval European, the Black Death must have seemed like the end of days. Disease gripped the continent, killing at least a third of the population.
Although that first wave of infections tapered off by 1353, regular plague outbreaks became a feature of medieval and Renaissance life, with epidemics breaking out every 10 or 20 years.
For that reason, the pandemic that began with the Black Death is considered by historians to have lasted until at least 1840 — almost 500 years. Plague is still endemic to all continents except Oceania, but today it can be effectively treated with antibiotics if the infection is caught in time.
The prognosis for COVID-19
Although there are many paths a pandemic can take, they all have something in common.
Messy endings.
That's because, to be truly over, each pandemic has to end in two different ways: medically and socially.
A pandemic's medical ending doesn't occur until fatalities drop low enough that the outbreak is no longer a public health crisis. A pandemic's social ending, on the other hand, comes about when people decide to go back to their normal lives and stop allowing the threat of infection to shape their behaviour.
As we all grow tired of living with restrictions, governments and populations worldwide are moving closer to the COVID-19 pandemic's social ending. Its medical ending will likely take longer and be more difficult to pin down.
Future COVID mutations may be milder than the current variants, or they may stay lethal enough to cause more global emergencies. Only one human illness has ever been totally eradicated — smallpox — and it took a highly effective vaccine, a global vaccination campaign and almost 200 years to achieve that victory.
Whether we find a fix for COVID, it burns out, or it settles in, the only certainty is that this virus will be with us in one form or another for many years to come.
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