Fist Bumps and High-5s Keep Germs Away

The results from a study suggest that fist bumps transmit significantly less bacteria than handshakes.

Bumping fists with patients and health care professionals could help to control the spread of bacteria in hospitals, according to the results of a recent study published in August 2014 issue of the American Journal of Infection Control.

In response to a recent call from the Journal of the American Medical Association to ban handshakes from the hospital environment, researchers from the Institute of Biological, Environmental, and Rural Sciences at Abersystwyth University in the United Kingdom sought to determine if less formal greetings transmitted fewer microorganisms than traditional handshakes.

During the trial, a greeter dipped a sterile-gloved hand into a culture of nonpathogenic Escherichia coli and, after a film of bacteria had dried onto the glove, exchanged a handshake, fist bump, or high-5 with another sterile-gloved researcher. The recipient’s glove was immersed in buffer to assess the number of bacteria transmitted during the exchange. To determine the amount of contact for each greeting, the greeter’s glove was sprayed with paint and the exchanges were repeated. The area of paint transmitted to the recipient’s glove was then measured.

Significantly more bacteria was transmitted during a handshake than both a fist bump and a high-5, the results indicated. Nearly twice as many bacteria were transferred during a handshake when compared to a high-5, and the lowest transmission of bacteria was consistently observed during fist bumps.

The results of the study also found that the contact area, duration, and strength of greetings were all associated with the amount of germs transmitted. Not surprisingly, larger contact areas during a greeting were correlated with an increase in the amount of bacteria transmitted, and handshakes had the most contact of the 3 greetings. When the informal greetings were extended to the full 3 seconds of the handshake model tested, the amount of germs transferred during a fist bump significantly increased, but did not significantly change during a high-5. When different handshake grip strengths were compared, strong grips resulted in a significantly increased amount of transmitted bacteria than moderate strength handshakes.

The researchers of the study note that other factors affect the spread of germs outside of the laboratory. In everyday life, different parts of the hand might have different amounts of bacteria and could depend on a person’s hygiene habits, job, and location. Nonetheless, favoring fist bumps in hospital settings could help to reduce the spread of bacteria.

“It is unlikely that a no‐contact greeting could supplant the handshake; however, for the sake of improving public health we encourage further adoption of the fist bump as a simple, free, and more hygienic alternative to the handshake,” the authors of the study conclude.