The COVID experience was a painful reminder pandemics can actually happen.
Live in a modern, healthy society long enough, it can seem like we're immune, like pandemics are historical artifacts. We live in the future. We don't have flying cars yet, but at least we've conquered pandemics.
Then the SARS-CoV-2 virus spread, bringing COVID-19. By March, 2020, the World Health Organization (WHO) made it official: that ancient relic called a pandemic was here again. And it was bad. Current WHO estimates have the global death toll from COVID-19 at over 7 million people.
It's not clear what the world learned from the experience. But if we learned anything, it was that the danger of pandemics is still out there.
This is especially true with RNA-based viruses like SARS-CoV-2. Every virus contains either DNA or RNA -- it's the genetic code that lets them take over host cells in humans and replicate. Both DNA and RNA viruses are dangerous. Smallpox is a DNA-based virus, and in the 20th Century, no less than 300 million of us have died from it. But RNA viruses have a devious trick up their sleeve that makes them much harder to control.
Turns out, RNA viruses like SARS are chemically unstable. They're reactive to the environment, and prone to degradation, meaning they easily lose their ability to be infectious. This sounds like a good thing. And in the outside world, it is. Throw light or heat on an RNA virus, it quickly dries out and loses its power.
But inside a host, this instability has a different effect. It means the virus is frequently mutating. RNA viruses work overtime in a host to find the right formula to take over cells and replicate. They don't degrade, they adapt. It's why we keep needing new versions of vaccines. RNA viruses rapidly change into new forms that outsmart vaccines. Once an RNA virus spreads to humans, it gets out of control fast.
Even when we get rid of them, they're never "cured". RNA viruses don't go away. They evolve.
This makes a research paper published last month (June, 2025) pretty disturbing. Typical of University Research publications, the paper has an absurdly long title: "An ancient influenza genome from Switzerland allows deeper insights into host adaptation during the 1918 flu pandemic in Europe". But it reveals something shocking: researchers managed to reproduce the deadliest RNA virus in modern history.
The 1918 Spanish Flu was caused by an RNA virus. It hit the same year that World War I ended -- and it killed twice as many people. Estimates of the number of deaths from the Spanish Flu pandemic range as high as 100 million. Unlike COVID, the Spanish Flu targeted younger people in the population, killing those in their 20s, 30s, and 40s, often within 48 hours of showing symptoms.
The spread was lightning fast. One third of the global population suffered within a year of its debut, helped by movements of trains and ships during the war. There were no antibiotics or vaccines. The only way out was waiting for enough people to die or get immunity so it would stop spreading. Bodies piled up faster than they could be buried.
Before COVID, when someone talked about a pandemic, they were talking about the 1918 Spanish Flu.
Fortunately, the exact virus -- a subtype of H1N1 influenza A virus -- faded away by 1920. There are versions of the flu we prepare for every season, but the Spanish Flu is a relic of history.
Until now.
Incredibly, researchers just fully decoded the entire genome of the Spanish Flu virus from a preserved Zurich patient. Specifically, tissue was sampled from an 18-year old man who died of the virus on July 15, 1918. They extracted RNA from a piece of the victim's lung. They followed complex steps to clean the sample, and convert it into DNA libraries for sequencing. Ultimately, researchers meticulously pieced together the genetic blueprint of the 1918 flu virus from this century-old biological sample.
Analyzing this infamous virus only revealed why it was so deadly. The genome had two mutations in its proteins that help it resist the human immune system. And one mutation to help it attach to human cells. This specimen from July of 1918 was, indeed, well equipped to kill humans on a massive scale.
Will the data help efforts to control viruses in the future? Maybe. Does having a completed version of a deadly virus in a lab pose any danger to the modern world? Let's hope not. Because if the Spanish Flu does find its way into humans and spread once again, it won't be in its old form.
Like all RNA viruses, it will evolve.