This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

MEMPHIS, Tenn. (WREG/CNN) — Many still have questions on whether to wear a mask and when, and this video from the New England Journal of Medicine may help with that decision.

COVID-19 is highly contagious and doctors say it can travel through droplets when you cough, sneeze or just talk to someone who’s next to you.

Now they want to show you what they mean.

Video shows neon specks — that’s spit. There’s a big difference between when someone is wearing a mask and isn’t.

The demonstrations may be gross, but they offer a revealing look at one of the main ways doctors believe COVID-19 is spreading.

“Putting a mask over someone who is sick can help them from spraying these things, as you saw in the video, effectively around them. That’s a good thing,” said Dr. Stephen Threlkeld, a Memphis infectious disease specialist.

But, he said, a mask doesn’t make you invincible.

“(There’s) definitely a danger when you wear a mask (from) picking at them and adjusting them and touching your face because of them,” he said.

Still, the CDC recommends everyone wear a mask while out in public, especially since many people could have COVID-19 and not show any symptoms. The CDC says a mask cuts down on the spread.

Threlkeld stressed one thing to remember at the grocery store:

“Every time you touch something at a grocery store (that) someone (who has COVID-19) touched in front of you … the virus is still sitting there. You’ve touched the virus, you’ve touched your mask. You’ve given yourself the infection that way.”