(CNN) The number of coronavirus cases around the world has soared past 113,000, with more than 4,000 deaths.

Even the man who oversees New York City's major airports and bus terminals has tested positive -- leaving many wondering how rampant the virus will get.

CNN readers have been asking sharp questions about coronavirus every day. And each weekday, we'll select some of the top questions and get you the answers.

Here are some of the most recent popular questions:

Q. If traveling on a plane, how do I stay safe?

It's not the cabin air you need to worry about. It's keeping your hands clean.

Always be mindful of where your hands have been, travel medicine specialist Dr. Richard Dawood said.

Airport handrails, door handles and airplane lavatory levers are notoriously dirty.

"It is OK to touch these things as long as you then wash or sanitize your hands before contaminating your face, touching or handling food," Dawood said.

"Hand sanitizers are great. So are antiseptic hand wipes, which you can also use to wipe down armrests, remote controls at your seat and your tray table."

Q. Since a plane's cabin keeps circulating air, will I get sick if another passenger is sick?

Most viruses don't spread easily on airplanes because of how the air circulates and is filtered, the Centers for Disease Control and Prevention says

Modern commercial jets recirculate 10-50% of the air in the cabin, mixed with outside air.

"The recirculated air passes through a series of filters 20--30 times per hour," the CDC says.

"Furthermore, air generally circulates in defined areas within the aircraft, thus limiting the radius of distribution of pathogens spread by small-particle aerosols. As a result, the cabin air environment is not conducive to the spread of most infectious diseases."

Still, try to avoid contact with anyone sneezing or coughing. And if you're feeling sick, cover your entire mouth and nose with the inside of your elbow when you cough or sneeze.

Q. What exactly does 'older' adults mean? What is the age threshold?

Anyone over 60 and those with underlying health problems should try to avoid places with large crowds -- such as movie theaters, busy malls and even religious services, infectious disease experts say.

"This ought to be top of mind for people over 60, and those with underlying health problems," said Dr. William Schaffner, a Vanderbilt University professor and longtime CDC adviser.

"The single most important thing you can do to avoid the virus is reduce your face to face contact with people."

But why is age 60 often used as a threshold for those who need to be extra cautious?

"We now know more about who is at risk," US Surgeon General Jerome Adams said.

"(The) average age of death for people from coronavirus is 80. Average age of people who need medical attention is age 60."

Q. Should I avoid Chinese, Korean or Italian people?

No. Not everyone in a certain demographic is at risk for coronavirus.

And social stigmas often cause more harm than good -- whether they're directed at a nationality or at a profession, like health care workers.

"Stigma affects the emotional or mental health of stigmatized groups and the communities they live in," the CDC says . "Stopping stigma is important to making communities and community members resilient."

Already, we've seen damaging fallout from coronavirus stigmas. Chinese-American businesses have been devastated financially, and restaurant workers have been laid off.

Q. Can you get coronavirus through food?

"Coronaviruses are generally thought to be spread from person-to-person through respiratory droplets. Currently there is no evidence to support transmission of COVID-19 associated with food," the CDC says

"In general, because of poor survivability of these coronaviruses on surfaces, there is likely very low risk of spread from food products or packaging that are shipped over a period of days or weeks at ambient, refrigerated, or frozen temperatures."

Q. I have plans to go on a cruise. Should I rebook or cancel?

"US citizens, particularly travelers with underlying health conditions, should not travel by cruise ship," the US Department of State says

Several cruise ships have been linked to coronavirus, including the Diamond Princess, where more than 700 people were infected . At least seven of those patients have died.

Since the coronavirus outbreak started, some cruise lines have implemented more flexible rebooking or cancellation policies

Q. If I have a weakened immune system, should I cancel my travel plans?

People who are immunocompromised "are at higher risk from this illness, as well as other illnesses like the flu. Avoiding contact with ill people is crucial," Washington state's Snohomish Health District said.

Snohomish County is where the first US case of novel coronavirus was reported in January. Since then, more than 700 people in the US have been infected, and at least 26 have died -- mostly in Washington state.

Even before the coronavirus outbreak, those with weakened immune systems often suffered more severe complications when sickened while traveling.

"While rates of infection may not differ significantly between healthy and immunocompromised travelers, the latter are at greater risk for severe disease ," according to researchers from the Washington University School of Medicine.

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