一年一度畢業季，穿上學士服，站在臺下，等待被念到名字的那一刻，走上臺去，接過學位證書，和校長親切握手，打住，校長少說也要和幾千名學生握手，這樣下來，手豈不是成了細菌傳播的溫床？近日來自《學校護理雜志》的研究為我們找到了答案。

It’s graduation season. And some scientists got to wondering whether the folks who shake hundreds of hands while passing out diplomas run the risk of coming away with a fistful of infectious microbes, such as Staphylococcus aureus. Good news—turns out the risk of being passed a disease-causing bacterium while pressing the flesh is pretty remote. That’s according to a study in the Journal of School Nursing. [David Bishai et al., "Quantifying School Officials’ Exposure to Bacterial Pathogens at Graduation Ceremonies Using Repeated Observational Measures"]

The researchers swabbed the palms of 14 school officials before and after graduation. They found that before the ceremony, and even after a slathering of sanitizer, hands were home to plenty of nonharmful bacteria. On the infectious scorecard, one dean brought Staph aureus to a commencement. Two others at a different ceremony walked away with it. And one of those samples came from a left hand, which didn’t participate in any of the meeting or greeting. So the math says that of more than 5,000 handshakes, just one may have passed along something less welcome than a sheepskin.

So if you’re graduating this spring, feel free to shake hands. While you wonder if the last person who wore that robe had anything contagious.

—Karen Hopkin