It's common knowledge to avoid people who are coughing and sneezing, but there is also worry about so-called "silent spreaders" — people who are showing no symptoms of the coronavirus but who can still pass it on to others.
"Silent spreaders appear to be a much more common phenomenon than we initially appreciated," Dr. Oz told Inside Edition.
Some people are what's known as "pre-symptomatic," which means they will get sick in two-three days but are already contagious. There's also growing evidence that some people infected with COVID-19 won't show any symptoms at all.
A new study published in Eurosurveillance, a journal on infectious diseases, found that an estimated 17.9% of passengers who tested positive for COVID-19 on the Diamond Princess cruise ship remained asymptomatic throughout, Forbes reported.