You had coronavirus questions. We had doctors answer them

A monitor displayed an image of a thermal scanner as passengers passed through a quarantine station at Narita Airport in Narita, Japan.Kiyoshi Ota/Bloomberg

As coronavirus cases increase in number, so do the questions from Globe readers. Here are some of the more common queries submitted to us in the past few days. In many instances, it’s too early to provide firm answers, but several experts did their best.

Should people cancel their vacation travel plans to avoid catching Covid-19?

If you were planning to visit China, Iran, Italy, or South Korea, the answer is yes. The US Centers for Disease Control and Prevention advise against all nonessential travel to those nations.

For trips anywhere else, it depends on where you’re going, your conveyance, and your tolerance for risk.

“You don’t know where the virus is going to be,” said Dr. Stanley Perlman, professor of microbiology and immunology at the University of Iowa and a member of the American Academy for Microbiology.

If you’re traveling overseas, and an outbreak occurs in the place you visit, the risk of getting sick is not your only concern: You could get quarantined on your return, he noted.

Dr. Nahid Bhadelia, medical director of the Special Pathogens Unit at Boston Medical Center, urges would-be travelers to check the CDC website and consult their local board of health. In Boston, she said, the Mayor’s Health Hotline is a good resource: 617-534-5050 or toll-free: 1-800-847-0710.

“At the present time,” said Dr. Daniel R. Kuritzkes, chief of the Division of Infectious Diseases at Brigham and Women’s Hospital, "at least within the continental United States, there’s no compelling reason not to travel.”

Dr. Mark A. Gendreau, chief medical officer at Beverly Hospital, who has studied the spread of infections on airlines, wouldn’t hesitate to travel domestically on an airplane, where the ventilation system is better than in an office building.

But he said he wouldn’t get on a cruise ship; they have served as a source of infection in the past.

“It’s really tight quarters and you’re going to be on there more than a couple of hours,” he said.

Should people who have lung conditions or other vulnerabilities stay inside?

No.

“I don’t think you’re going to get this walking down the street,” Perlman said. “The odds are close to zero.”

At most, if you’re really nervous, you might avoid mass gatherings such as church services or concerts. But you don’t need to take any greater precautions than you would during flu season, Perlman said.

Kuritzkes doesn’t think there’s any reason to avoid public gatherings. “At this point, it’s a little early for people to be overly concerned about that,” he said. “I would go about my regular daily activities and not be too worried about it.”

Rather than sequestering themselves, people just need to "practice great hand hygiene and not touch their face when they’re out in public,” Gendreau said.

What are the symptoms of coronavirus, and how is it treated?

Doctors do their best to answer questions about the novel virus infecting more and more every day.

Does getting sick with Covid-19 confer immunity? Or can you get it again?

“No one knows,” Perlman said. There have been reports of people diagnosed with Covid-19 who seemed to recover and tested negative, and then tested positive afterward — but it’s not clear if the infection became dormant and then resurged, or if the person was reinfected.

Perlman thinks it’s unlikely anyone got reinfected. That didn’t happen with the other serious coronaviruses, SARS and MERS.

Typically deep lung infections like Covid-19 confer at least some immunity. “The viruses that cause pneumonia almost always induce some sort of protection,” he said.

How long does the virus live on surfaces? What cleaning products kill it?

“We know that it survives for some time on inanimate surfaces — two to five days,” Perlman said.

But the risk is greatest when you grab a subway pole or a bathroom door handle moments after a sick person smears it with germs.

As for cleaning, Perlman said, “Bleach works extremely well. Soap and water work well.” Both destroy the virus instantly.

Heating it to 130 degrees Fahrenheit for 10 minutes also kills it.

Dishwashers and laundry machines, if functioning properly, will destroy the virus, he said. But if someone sneezes on a salad or some cold cuts, the virus is likely to survive in the food for some time.

Perlman’s comments are based on experiences with other coronaviruses, such as SARS, and his knowledge of this type of virus. Tests on the survivability of the new coronavirus have not been done.

Based on a study of SARS, Gendreau said a solution of alcohol with 5 percent hydrogen peroxide can eradicate the virus within an hour. When he gets on a plane, he uses alcohol-based hand sanitizing wipes to clean the armrests and tray.

Will the virus that causes Covid-19 recede when the weather gets warmer?

“We really have no idea,” said Kuritzkes. Colds and flus tend to be more common in winter months, because people spend more time inside, close together, and because the viruses prefer cooler temperatures.

“How this virus will behave, we don’t know,” he said.

The public has been advised not to wear face masks because they don’t provide protection and because health care workers need them. But if masks don’t protect members of the public, how do they protect health care workers?

Health care workers don’t wear the drugstore face masks. Those are needed for sick patients in the hospital, to prevent them from spreading the virus to caregivers and others, Kuritzkes said.

Doctors, nurses, and others wear a more sophisticated mask, called an N95 respirator, that filters out the tiniest particles. While it’s possible to buy them online (if they’re not sold out), the N95s are not for laypeople. They need to be specially fitted and require training to take on and off. People with breathing difficulties aren’t supposed to use them. And health care workers truly need them more than you do, because they are exposed to so many dangerous germs in the hospital.

The virus is spread through droplets spewed by infected people when they cough or sneeze. The droplets travel a few feet at most and then quickly fall to a surface. By covering the mouth and nose, the drugstore mask can keep an infected person from spreading contagious droplets.

But it won’t protect a healthy person because people don’t usually catch the virus by breathing it in. The main way people get infected is by touching a surface where those droplets have fallen, and then touching their mouth, nose, or eyes. A mask might actually make matters worse, if it’s uncomfortable and prompts you to touch your face more often, or if it gets dirty and you re-use it. Or if it creates a false belief that you’re protected.

You get far more protection from — you guessed it — regular handwashing.

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