To prevent catching the novel coronavirus, do as public health officials say, not as they do.
That means not touching your face. The advice is simple, but the task is herculean, even for those dispensing it.
Sara Cody, the public health director for Santa Clara County, California, slipped up at a news conference on Friday, for example.
"Start working on not touching your face," she said.
Less than a minute later, she raised a hand to her mouth and licked a finger to turn a page in her notes. As of yesterday, almost 4.5 million people had watched the clip shared on Twitter.
That same day in Washington, Democrat representative Alexandria Ocasio-Cortez scratched her nose and repeatedly brushed her hair away from her face while answering reporters' questions at a news conference on Covid-19 precautions.
The trend continued when Debbie Birx, coronavirus response coordinator for the White House, and Robert Redfield, director of the Centers for Disease Control and Prevention, who have both stressed the importance of the no-touching-your-face rule, touched their faces during a Covid-19 task force briefing with President Donald Trump.
"I haven't touched my face in weeks - in weeks," Trump jokingly said during the briefing. "I miss it."
But as many people pointed out on Twitter, Trump has been caught on camera touching his face several times in recent days.
And who can blame him? Touching your face feels as natural as blinking.
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"It's very hard to change because you don't even know you're doing it," William Sawyer, a family doctor in Sharonville, Ohio, told The Washington Post.
In 2015, researchers observed a class of medical students during a lecture in which they averaged 24 face touches an hour.
The Daily Show With Trevor Noah latched onto the trend Wednesday, compiling examples of five public officials, ranging from governors to World Health Organisation representatives, touching their faces while giving press statements about preventing coronavirus.
Other offenders include Florida Governor Ron DeSantis, New York Mayor Bill de Blasio and Michael Ryan, executive director of the World Health Organisation's health emergencies programme.
In the past several weeks, as anxieties over the novel coronavirus have increased, social media filled with memes, jokes and GIFs expressing people's frustration with their inability to keep fingers off their faces.
"Realising basically all I do is touch my face," comedian and actor Seth Rogen tweeted Wednesday.
Doctors say keeping your hands off your face is the most effective measure you can take to avoid catching coronavirus and most other common viral infections. Frequently washing your hands with soap for 20 seconds, or using hand sanitiser, is another important precaution.
But if you end up touching your face despite your best efforts, know you're not alone. Look no further than Vice President Mike Pence, who is in charge of the Covid-19 outbreak response, pinching his nose seconds before shaking hands with the top public health experts working to prevent the spread of the virus.