When Barack Obama succeeded George W. Bush as president of the United States, the former holder of the office gave his successor two pieces of advice.

"The first piece of advice was trust yourself," Obama recalled in a 2016 interview with CBS's Face The Nation.

"The second piece of advice was always use Purell hand sanitizer, because if you don't, you're going to get a lot of colds, because you're shaking a lot of hands."

That advice certainly seems more prescient during this coronavirus epidemic, and it also encapsulates the potential public health risks associated with the custom. While some doctors would be happy to see the gesture disappear, it could be extremely challenging to end such a culturally ingrained custom.

Leading infection risk factor

"Shaking hands is absolutely one of the leading risk factors for transmitting or acquiring microbial infection such as COVID-19," said Paul Pottinger, an infectious disease professor at the University of Washington in Seattle.

Bernadette Walker, left, and Deborah Johnson, along with other members, bump elbows as they arrive for a worship service at Destiny World Church in Austell, Ga. Pastor Wilbur Purvis III, whose sermon was on the coronavirus and how to keep cool in a crisis, said 'We're not shaking hands today, we are doing elbow bumps.' (Curtis Compton/Atlanta Journal-Constitution/Associated Press)

Micro-organisms that might cause infections can live on the surface of the hand, especially the palm of the hand. When someone shakes hands, those microbes may be transferred from the skin of one person to the skin of the other, Pottinger said.

That by itself is usually harmless, but the threat comes when a person who has just received that germ then touches their face and allows those microbes to get into the mouth and nose, or eyes, he said.

Pottinger says people can shake hands, but they just have to make sure they clean their hands very carefully afterward.

"Why take the risk? Why not just skip the gesture altogether?"

And that's why Pottinger and others would like the gesture to disappear and hope the pandemic could perhaps create an opportunity for safer, alternative methods of greeting people.

Some have already begun to emerge. Pictures have circulated showing fist bumping as an alternative, not a particularly new way of greeting. Now people have added gestures such as foot shaking or elbow bumping. Others, such as California doctor Mark Sklansky, have suggested the Asian cultural greeting of bowing as an alternative, or the Hindu Namaste hand clasping greeting which is popular in southeast Asia.

Meanwhile, those more sci-fi-minded believe this could be the time to introduce the Star Trek Vulcan fingers spread greeting as a potential replacement that involves no touching.

"My hope is that people recognize that — and I think we need collectively to educate people — about why even after this pandemic is over, a handshake is a really bad idea." said Dr. Sklansky, chief of pediatric cardiology at Mattel Children's Hospital UCLA.

"From an infectious disease standpoint, it's a terrible concept to shake. Hands are a phenomenal vector for disease."

(Scott Galley/CBC)

Although not an epidemiologist, Sklansky, who is admittedly a "germaphobe," has been on a crusade against the handshake for years, gaining some international attention after he wrote an editorial recommending against it in 2014 in Journal of the American Medical Association.

Handshake free zones

In it, he advocated for the ban of the handshake in health-care environments, and called for the implementation of a "handshake-free zone (HFZ) with signs posted asking people 'to please refrain from shaking hands while on these premises.'

"Some people I talked to sort of laughed when we wrote the handshake paper back in 2014. And many of those people aren't laughing anymore," he said.

A few years later, he conducted an experiment, establishing a HFZ in his hospital's neonatal intensive care unit to see if such a zone would have an impact on handshaking.

He found the HFZ decreased the frequency of handshakes within the NICU, and that families were very happy to avoid hand shaking to protect their babies. As well, a vast majority of health-care workers were happy to stop shaking hands.

Instead, when greeting, people felt it very important to be addressed by name, have someone smile at them and look them in the eye, he said.

Now, in the wake of the pandemic, Sklansky is hoping HFZs gain some traction, and not just in hospitals.

"We want to discourage the handshake. And so I think the handshake-free zone will help discourage it," said Sklansky, who has also created a YouTube video for his cause.

Deeply embedded ritual

"I think it should happen and I think it will happen. I'm just eager for it to happen quicker than it might because I know there's going to be pushback," he said. "It's not easy to change such a deeply embedded cultural ritual."

The handshake dates back thousands of years, and some historians believe it to be a gesture of peace to reveal that the hand was not carrying any weapons. Another theory postulated it was to seal a promise or an oath. It may have become popularized by the 17th century by Quakers, "who viewed a simple handclasp as a more egalitarian alternative to bowing or tipping a hat," according to History.com.

Now, it's commonly used as a social greeting ritual, particularly in Western cultures, but also all across the world.

It has come to symbolize the finalization of business deals, or become important symbolic political gestures, especially between geopolitical rivals seeking peace.

Juliana Schroeder, an assistant professor in management of organizations at Berkeley Haas at University of California, who has done research on the gesture, found shaking hands can improve the outcome of negotiations for both sides

"It has this psychological signal that it sends, which is that the person who is offering their hand is indicating that they're willing to engage in some sort of business contacts with you," she said. "That they're willing to be co-operative. And that's the signal that's very much inferred by the other person."

Handshakes between political enemies such as then Israeli prime minister Yitzhak Rabin, left, and then Palestinian leader Yasser Arafat have come to represent significant gestures toward peace. (Ron Edmonds/Associated Press)

But rituals like the handshake can become difficult to change because they become so deeply ingrained in a society and end up being signals of one's membership in the group, she said.

If there's no clear replacement that the entire society gets on board with, "'like 'now we're doing elbow taps,' then as soon as the lockdown ends ... people may just go back to the handshake.," she said.

Interim replacement gesture

Andrew Molinsky, a professor of organizational behaviour at Brandeis University's International Business School in Boston, said he believes the handshake is just too ingrained to disappear forever and any new greeting to emerge will be an interim replacement gesture.

He could see people co-creating rituals in some way that sort of signify a similar thing.

"Like, 'Hi. Nice to meet you,' then there might be a laugh. There might be sort of a move for a handshake, but then the step back, and be like these little dances that get created."

But if a vaccine is discovered, "I could imagine people going back to the handshake," he said.