Black light experiment shows how quickly a virus like Covid-19 can spread at a restaurant

A viral video from Japan aims to show how easily germs and viruses can spread in restaurants when just one person is infected.

The experiment simulates the atmosphere at a buffet restaurant or on a cruise ship. It was conducted by the public broadcasting organization NHK in conjunction with health experts.

The video shows 10 people coming into the restaurant, with one singled out as the "infected" person. Each participant goes about the buffet as they normally would, not considering a potential contamination.

At the end of the video, the participants are cast under black lights illuminating where the "infection" has spread.

The substance, used to signify the germs, can be seen on food, serving utensils and platters, and even on the faces of some of the participants.

Here's what the experts have to say

While these kinds of experiments are not new, John Nicholls, a clinical professor in pathology at Hong Kong University, said they demonstrate how quickly a virus can spread, especially when hand washing is not performed.

"What the video demonstrated, is that it will spread to surfaces and to people very efficiently," Nicholls told CNN, "and I think it really highlights the need of what people have been saying about hand hygiene to stop the spread of disease."

This nurse demonstrates just how fast germs spread even if you're wearing gloves

This nurse demonstrates just how fast germs spread even if you're wearing gloves

However, Nicholls said that the situation is "artificial" because so much emphasis is placed on the touching alone.

Kentaro Iwata, an infectious disease specialist at Kobe University, agreed.

"The experiment just described the possibility of the spread by contact, and that is not proof of what happened, so the distinction has to be clearly made between what could happen and what did happen," Iwata told CNN.

But both experts said the experiment is a good way to show the importance of hand washing.

For the sake of science, Nicholls said it would be even more effective to see the experiment done after the "infected" person washes their hands for five and then ten seconds.

"So the general public gets some concept of the mechanism of how much the use of hand washing can actually reduce the transmission of potentially infectious material," Nicholls said.

CNN's Bex Wright contributed to this report.