They tell us not to touch our face. But watch how often they do it.

To prevent catching the COVID-19 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 Friday, for example. "Start working on not touching your face," she said.

Less than a minute later, she raised hand to mouth and licked her finger to turn a page in her notes. As of early Thursday, almost 4.5 million people had watched the clip shared on Twitter.

The same day in Washington, Rep. Alexandria Ocasio-Cortez, D-N.Y., 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 Wednesday 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.

"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 on Wednesday.

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 Organization representatives, touching their faces while giving press statements about halting the coronavirus.

Other offenders include Florida Gov. Ron DeSantis, New York Mayor Bill de Blasio and Michael Ryan, executive director of the World Health Organization's health emergencies program.

In the past several weeks, as anxieties over the coronavirus have increased, social media filled with memes, jokes and GIFs expressing people's frustration with their inability to keep fingers off their faces.

"Realizing 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 the coronavirus and most other common viral infections. Frequently washing your hands with soap for 20 seconds, or using hand sanitizer, is another important precaution.

But if you end up touching your face despite your best efforts, 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.

How to stop touching your face

So really, how do you stop touching your face? A lot of ideas have been floated in the media:

• Use tissues to tend to itches or eyeglass adjustments.

• Become aware of your compulsive behavior. Even video yourself.

• Place notes around your desk not to touch your face. Or set periodic device reminders.

• Practice with a scarf on your face, to see how often you touch it.

• Or wear gloves or tape on your fingers (although a glove itself could also carry germs).

• Sit on your hands during meetings.

• Occupy your hands with stressballs or other objects.

• Or, simply don't think about touching your face. Put another way, don't worry about it so much. “My general advice would be that people should try to reduce their stress overall, as opposed to obsessively worrying about what they touch,” Stew Shankman, a professor of psychiatry and behavioral sciences at Northwestern University, told The New York Times.

Sources: New York Times, today.com, NBC News, Huffington Post, Washington Post