The debate on medical masks: do they protect against the coronavirus?

All over the world people are buying protective masks in the hope of keeping the new virus detected in China at bay. Some companies require their employees to wear them. South Korean schools have ordered parents to equip their children with masks and hand sanitizing gel when they return from winter vacation. In China, a chain of pharmacies was fined for multiplying the price of this product in the face of incessant demand.

But do the masks work? It depends.

All viruses are small enough to fit through the classic rubber-fitting medical mask. But germs don't usually spread through the air one at a time, said Dr. Mark Denison of Vanderbilt University Medical Center in Nashville. Denison studies SARS and MERS, which are both coronaviruses, the same family that the new virus belongs to.

Instead, the viruses are passed from one person to another in tiny droplets when you cough or sneeze. These drops fall on hands or other surfaces, where others touch them before they get into the eyes, nose, or mouth.

Masks can block large drops from a cough or sneeze, which gives them some value, Denison said.

Also, a person with a mask cannot touch his nose and mouth. That can prevent the wearer from spreading germs that someone who is sick has left on other surfaces, he said.

The masks are "a very sensible precaution" as scientists work to determine exactly how the new virus spreads, said Oxford University researcher Trudie Lang.

However, none of this is based on serious research. No one has compared groups of people with and without masks exposing them to the new virus, Denison said. A 2017 analysis of several studies of health-care workers indicated that the masks provided some protection against SARS, although the authors noted that "the existing evidence is weak and the findings are inconsistent.

The right prevention

The best way to avoid catching the new virus is to wash your hands with soap and water. If soap and water are not available, use an alcohol-based hand sanitizer. This is the same advice as for avoiding the common cold and flu.

The U.S. Centers for Disease Control and Prevention (CDC) recommends masks for people being tested for the new virus, confirmed sick people, people they live with, and people who care for them. The CDC recommends that airline staff offer masks to sick travelers.

The CDC also advises that health care workers who care for patients with the new virus take additional precautions such as goggles or full-face masks.

UNICEF said Wednesday that it had shipped six metric tons of respiratory masks and protective suits for health workers to China.

In Tokyo, hotel employee Hasumi Tsuchida, 21, said she wears a mask. "I work in a hotel where many guests are from China," she said. "I worry a little when foreign guests arrive."

In some countries it is common for a person to wear a mask if they are sick, have an allergy outbreak or on days when contamination is especially high. The new virus has triggered the demand for masks worldwide.

Very high demand

Respilon, a Czech company that manufactures its "nanofiber" masks in China, sold 700,000 last year worldwide. Since last week it has received orders for another 7 million. The problem is that it cannot manufacture them because the Chinese government extended the Lunar New Year holidays in an attempt to contain the spread of the virus.

In Taiwan, where the celebrations are over, the factories are up and running. The government has already distributed 23 million masks, according to Prime Minister Su Tseng-chang, saying the country could produce another 4 million units a day.

A mask factory in Shanghai was working at full capacity despite the holidays.

"Now we work 24 hours, 2 shifts a day, 12-hour shifts," said Liao Huolin, the company's president. "We have violated labor laws (...) but the workers understand.

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