In the cold and flu season, how we greet each other greatly affects how we spread germs.
Could a handshake mean a higher chance of getting a cold? Would a fist bump or high-five be better?
ABC News asked a group of volunteers at the International Food Safety Training Laboratory at the University of Maryland to find out.
Dr. Richard Besser covered his hands with thousands of harmless E. coli bacteria for the experiment.
The bacteria transfer just like the dangerous kinds of germs that can get people sick.
When the experiment began, the volunteers used alcohol wipes so that their hands were completely free of E. coli.
Our first test: handshakes.
Besser shook hands with one volunteer who then shook hands with another volunteer. This continued down the line like in the telephone game to include many volunteers. They then pressed their hands into special plates that were incubated overnight.
When the results came back, the first volunteer had almost as many bacteria as Besser. Each of the other volunteers also had E. coli on their hands. It wasn't until the fourth volunteer that the number of E. coli appreciably declined. But even the last person in line got enough bacteria from the original E. coli ridden hands to get sick.
A fist bump told a different story.
Drastically fewer germs were passed on in the fist bump than in the handshake.
Fist bumps minimize the surface area and protect the fingers and palms from germs but they also reduce the length of time hands are in contact.
So what about a high-five?
The hands fully touch like in a handshake but the contact time is very short.
The transfer of germs ended up being just about the same as the fist bump. Both were much better than handshakes.
So during flu season think of mixing up the way you say hello. For those who want to be really careful, an elbow bump is even better.