When winter approaches, everyone gets ready for the flu season to wreak havoc on the NHS and cause many to fall ill. Influenza is a tricky little virus that can spread through the air, making it a difficult one for authorities to ensure everyone stays safe.
Australia had one of the worst flu seasons last year, with that nasty strain being affectionately dubbed the Aussie Flu.
It spread around the world, with the UK noticing a large spike in diagnoses and admissions to hospitals.
While there was a flu jab for H3N2, aka the Aussie Flu, experts are warning that if there was a mutation of the virus, it could cause untold damage on the world.
Professor Robert Dingwal has told the Sun: "A pandemic is when we see a shift, a really radical change that means the population has no real resistance to it."
There have been a bunch of pandemics to hit our world over the last few centuries, including HIV/AIDS, cholera, typhus, smallpox, measles, turburculosis, leprosy, malaria, yellow fever, Ebola and Zika.
One of the biggest concerns is a strain of influenza called H5N1, but you'd probably know it better as the bird flu or avian flu. That was first detected in Vietnam in 2004 and there were fears that if the strain combined with the human influenza virus, it could do the same amount of damage as the Spanish flu.
Fifty-nine people died from bird flu and experts found the virus wasn't able to effectively mutate to be transmitted from human to human.
Dr Jonathan Quick says if that H5N1 did manage to mutate, then it could definitely wipe out a huge portion of people.
Speaking to the Daily Mail, he said: "The big one is coming: a global virus pandemic that could kill 33 million victims in its first 200 days.
"Within the ensuing two years, more than 300 million people could perish worldwide.
"At the extreme, with disrupted supply of food and medicines and without enough survivors to run computer or energy systems, the global economy would collapse. Starvation and looting could lay waste to parts of the world."
Let's hope it gets nowhere near as bad as that.
But it does pose a tricky situation for scientists and researchers, as they are often on the backfoot when these things break and have to race ahead of a quickly changing virus in order to find a cure.
Featured Image Credit: PA