A viral video from Japan graphically illustrates how quickly a virus, like the coronavirus, can spread in a restaurant setting. The video shows 10 people entering a buffet-style eatery with one person being the “infected” guinea pig.

The 35-second video shows all 10 diners sharing a water pitcher and serving utensils as they fill their glasses and load up their plates with food, says Market Watch. Everyone eats, goes back for seconds and socializes for a half hour.

At the end of the clip, they are bathed in black light, showing the spread of the virus. The substance used in the video, which represents the virus, is seen on food, serving platters, utensils, and even on the faces of the participants, according to CNN.

“What the video demonstrated is that it will spread to surfaces and people very efficiently,” John Nicholls, a clinical professor in pathology at Hong Kong University, told CNN. “And I think it really highlights the need of what people are saying about hand hygiene to stop the spread of disease.”