In theory, by now all of us should understand why washing our hands, wearing masks, and keeping up sound hygiene practices is important during a pandemic. But nothing really drives the point home as effectively as a good old-fashioned demonstration.

Japan's public broadcasting network NHK has really brought the goods in a new video that's gone viral.

NHK worked with infectious disease experts from St. Marianna University School of Medicine in Kawasaki to set up a buffet-style meal for 10 people. They placed a little fluorescent paint on the hand of one 'infected' person to simulate a cough into their hand, and then let the participants have at the buffet for the next 30 minutes.

We're sure they all felt a little sick after the fluorescent lights were turned on to reveal the spread of that little bit of paint.

As you can see in the video above, the 'infection' got… everywhere. The paint spread to the hands of every single participant, and three ended up with the paint on their face.

The team discovered that the tongs, lids of the dishes, and the handle of the drink container were most to blame for the spread. This simple demonstration goes a long way to show just how easily germs can spread through contact and contaminated surfaces.

The World Health Organisation (WHO) keeps reminding everyone that regularly cleaning your hands with soap and water (for at least 20 seconds), not touching your mouth, eyes, and nose, and staying at the very least one metre (3 feet) away from other people, are the best methods for stopping the spread of the COVID-19 virus.

NHK and the experts did a second experiment too. This time, they were a lot more diligent about the hygiene practices used at the buffet. The dishes were separated, tongs were frequently exchanged for clean ones, and the participants were encouraged to clean their hands frequently.

In that version of the meal, no one else other than the originally contaminated person ended up with the fluorescent 'infection'.

The immediate lesson here appears to be "avoid buffet-style meals for a while". But it also points to a larger issue - humans can be grotty creatures, and we really need to stay aware of the risks and keep our personal hygiene up. Right now, lives depend on it.