To stop the spread of the pathogen, Winslet explains, officials need to determine its contagiousness, whether people without symptoms can infect others and who exactly is susceptible. “So far that appears to be everyone with hands, a mouth and a nose,” quips a local health official.

In late January, the 2011 thriller, which also stars Matt Damon and Gwyneth Paltrow, rocketed into iTunes’ top 10 movie rentals chart and became among the most popular films on Amazon Prime and Google Play. Though other pandemic movies, including Outbreak and 12 Monkeys, have also enjoyed renewed favour in recent months, none seems to resonate with viewers as much as Contagion.

That is likely because the movie’s screenwriter, Scott Z. Burns, conducted months of in-depth research into the science of pandemics. He then recruited several well-established epidemiologists to develop a realistic plot, edit the script and train the actors who would portray health officials, doctors and scientists.

“When I started talking to experts, they all said, ‘It’s not a matter of if there will be another pandemic, it's a matter of when,’” Burns says. “There’s nothing uncanny to me about doing research.” Amid a growing public health crisis, the movie’s near-documentary precision has also become a source of alarm for some.

Some fans believe the film’s fictional portrayal of destruction and high death toll are signs of what is to come, and suggest that officials are hiding information from the public. In the vacuum left by the absence of knowledge about this new virus, fear and misinformation have flourished. The movie, prescient as it is, predicted that, too.

Burns says Contagion was inspired by his father, who often worried about the possibility of bird flu becoming a human pandemic. Not wanting to make a conventional disaster movie, Burns turned to Dr Larry Brilliant, an epidemiologist who spearheaded the successful global eradication of smallpox.

At the time, around 2009, the public seemed to react strangely to the swine flu epidemic, Brilliant says. People acted almost disappointed that it was not as severe as health officials had warned, he says.

“We all started talking about the fact that modernity didn’t know what a real pandemic looked like,” he says. So they set out to create one.

Contagion tracks the arrival of a fictional virus called MEV-1 that sends officials from the CDC and the World Health Organisation scrambling to stop the outbreak and quell growing fear and distrust among the public. By the end of the film, chaos reigns and the disease's death toll has reached at least 26 million.

The fictional virus originates from a bat, then jumps to a pig and then a person, which reflects the fact that 75 per cent of new diseases in people come from animals, according to the CDC. Those diseases include HIV, Ebola, Sars and now, Covid-19.

In the film, knocking down trees in China displaces the bat and triggers the emergence of the virus, which shows how deforestation and the destruction of animal habitats makes such leaps more likely. The virus’ rapid spread, in just hours from Hong Kong to Chicago to Minneapolis, reveals the way increasing global travel can quickly turn diseases into pandemics, sometimes becoming impossible to contain.

“It was not going to be pure entertainment – it was actually going to have some public health messaging,” says Dr Ian Lipkin, a Columbia University epidemiology professor who served as the movie’s main scientific consultant. “The idea was to make people aware of the fact that emerging diseases will continue to emerge and re-emerge.”

Lipkin, who has identified hundreds of new diseases throughout his career, shared with Burns his experiences from 2003 on the front lines of the Sars outbreak in Beijing. Elliott Gould’s character in the movie, a University of California San Francisco scientist named Ian Sussman, is a nod to Lipkin.

Lipkin invited Winslet and actress Jennifer Ehle, who plays the researcher developing a vaccine for the virus, to his lab at Columbia to help them prepare for their roles. He developed a 3D model of the virus that rotates on screen. He helped Burns during post-production to ensure the whooshing and whirring sounds of the fictional labs were accurate.

In one scene, Winslet explains the concept of an R-0 – which refers to how many people each sick person is likely to infect, essentially a measure of contagiousness. The scene brought a wonky epidemiology term to the general public, much to the delight of public health professors and biology teachers who now play the movie for their classes each year.

Watching that scene, Brilliant says: “I thought I'd died and gone to heaven.”

Burns says that while filming the movie, Damon joked that they needed to amp up its fear factor and add some zombies for it to be a real Hollywood thriller. But Burns says it had become clear to him and director Steven Soderbergh that the film was even scarier because it was plausible, “as opposed to creating a monster that gives the audience this kind of distance from the story”.

Which brings us to 2020, when there is seemingly little distance between Contagion and real life.

Paltrow, who (spoiler alert) gets killed off in the first 10 minutes of the film, recently posted an Instagram selfie from a plane wearing a mask.

“I’ve already been in this movie,” she wrote. “Stay safe. Don’t shake hands. Wash hands frequently.”