There’s been a run of surgical masks in the US because of the coronavirus scare. You don’t need them, physicians say

In Wuhan, China, where the novel coronavirus has killed at least 106 people and sickened 4,515 more, wearing face masks is mandatory.

Half a world way in the US, major retailers are selling out of basic surgical masks amid panic from consumers.(So far, there have been five confirmed cases of coronavirus here.)

Surgical masks are a basic defense against some viruses, and they may be helpful in communities where health officials suspect viruses are circulating widely.

Flight crews are seen wearing masks at the international arrivals area at the Toronto Pearson Airport in Toronto, Canada, January 26, 2020. - Toronto Public Health confirmed Saturday that a case of the novel coronavirus that originated in Wuhan, China is currently being treated in a Toronto Hospital. (Photo by Cole BURSTON / AFP) (Photo by COLE BURSTON/AFP via Getty Images)

What we know about the coronavirus cases in the US

But in the US, there’s no need to wear surgical masks – or the N95 respirators physicians wear when treating viruses – says infectious disease expert Dr. Charles Chiu.

There’s no evidence of sustained novel coronavirus transmission in the US like there is in China, and the Centers for Disease Control and Prevention has not recommended Americans wear masks in public.

“Right now, there’s no evidence that [wearing face masks] is going to help prevent that infection,” Chiu, a professor of laboratory medicine at the University of California, San Francisco, told CNN. “I would not recommend that someone in the US who does not have direct exposure, did not recently travel to China…or in general that you go buy a face mask.”

Physicians wear masks, but the US public shouldn’t

Americans are scooping up two kinds of masks

The CDC doesn’t recommend public citizens wear either of them.

Surgical masks: While they do protect from large respiratory droplets (a spray from a sneeze or mucus from a cough), they don’t prevent against airborne droplets. Surgical masks aren’t considered respiratory protection by the CDC because they don’t filter smaller particles, and therefore isn’t effective in totally preventing coronavirus transmission.

“Wearing a surgical mask helps you prevent sharing your germs if you’re sick,” Saskia Popescu, a hospital epidemiologist and infection prevention expert, told CNN. “Surgical masks do not seal around the face, so while they offer some protection, it’s the N95 mask that offers the most protection.”

N95 respirators: Should you wear an N95 respirator depends on whether you’re a physician involved in a particular task.

The CDC does recommend that healthcare providers wear N95 respirators, face masks that filter at least 95% of airborne particles, if they treat a patient infected with the novel coronavirus.

Medical staff wearing protective suits ride down an escalator at Moscow's Sheremetyevo International Airport on Wednesday, March 18.

Hasidic Jewish men take part in a "social distancing" minyan in New York on Tuesday, March 17.

A patient in a biocontainment unit is carried on a stretcher in Rome on March 17.

A pedestrian walks a dog through a quiet street in New York on March 17.

People gather to collect free face masks in New Delhi on March 17.

Dermot Hickey, left, and Phillip Vega ask a pedestrian in New York to take their picture on a thinly trafficked Fifth Avenue on March 17. Many streets across the world are much more bare as people distance themselves from others. In the United States, the White House has advised people not to gather in groups of more than 10.

Students at the Attarkiah Islamic School wear face masks during a ceremony in Thailand's southern province of Narathiwat on March 17.

People wait outside a Woolworths store in Sunbury, Australia on March 17. Australian supermarket chains announced special shopping hours for the elderly and people with disabilities so that they can shop in less crowded aisles.

A member of Spain's Military Emergencies Unit carries out a general disinfection at the Malaga airport on Monday, March 16.

Displaced families near Atme, Syria, attend a workshop aimed at spreading awareness about the coronavirus.

French President Emmanuel Macron is seen on a screen in Paris as he announces new coronavirus containment measures on March 16. France has been put on lockdown, and all nonessential outings are outlawed and can draw a fine of up to €135 ($148). Macron also promised to support French businesses by guaranteeing €300 billion worth of loans and suspending rent and utility bills owed by small companies.

A police officer checks the temperatures of bus passengers at a checkpoint in Manila, Philippines, on March 16.

Flowers are stored prior to their destruction at a flower auction in Aalsmeer, Netherlands, on March 16. Lower demand due to the coronavirus outbreak is threatening the Dutch horticultural sector, forcing the destruction of products.

Two nuns greet neighbors from their balcony in Turin, Italy, on Sunday, March 15.

Pope Francis, inside the Church of San Marcello in Rome's city center, prays at a famous crucifix that believers claim helped to save Romans from the plague in 1522.

Passengers wait for their flights at Marrakesh Airport in Morocco on March 15.

US Vice President Mike Pence takes a question during a White House briefing about the coronavirus on March 15.

A Sea World employee sprays disinfectant in Jakarta, Indonesia, on Saturday, March 14.

People wait in line to go through customs at Dallas/Fort Worth International Airport on March 14. Travelers returning from Europe say they were being made to wait for hours at US airports, often in close quarters, as personnel screened them for the coronavirus.

Hundreds of people lined up to enter a Costco in Novato, California, on March 14. Many people have been stocking up on food, toilet paper and other items. As a response to panic buying, retailers in the United States and Canada have started limiting the number of toilet paper that customers can buy in one trip.

A member of the White House physician's office takes a media member's temperature in the White House briefing room on March 14. It was ahead of a news conference with President Donald Trump and Vice President Mike Pence.

Reporters in Arlington, Virginia, sit approximately 4 feet apart during a briefing by Marine Corps Gen. Kenneth F. McKenzie on Friday, March 13.

People walk past a closed Broadway theater on March 13 after New York canceled all gatherings over 500 people.

Body temperatures are scanned as people enter the Buddhist temple Wat Pho in Bangkok, Thailand, on March 13.

A Costco customer stands by two shopping carts in Richmond, California, on March 13.

A teacher works in an empty classroom at the Pompeu Fabra University in Barcelona, Spain.

A woman looks at an empty bread aisle in Antwerp, Belgium, on March 13.

Employees of the Greek Parliament wear plastic gloves ahead of the swearing-in ceremony for Greek President Katerina Sakellaropoulou.

A motorcyclist drives through disinfectant sprayed in Jammu, India, on March 13.

Workers prepare to construct an additional building on a hospital on the outskirts of Moscow.

Paul Boyer, head equipment manager of the NHL's Detroit Red Wings, wheels out equipment bags in Washington on Thursday, March 12. The NHL is among the sports leagues that have suspended their seasons.

Students leave Glacier Peak High School in Snohomish, Washington, on March 12. Beginning the following day, schools in the Snohomish school district planned to be closed through April 24.

An Uber Eats delivery biker stands at a deserted Piazza di Spagna in Rome.

People at a railway station in Seoul, South Korea, watch a live broadcast of US President Donald Trump on March 12. Trump announced that, in an effort to slow the spread of the coronavirus, he would sharply restrict travel from more than two dozen European countries.

Workers in protective suits disinfect Istanbul's Dolmabahce Palace on March 11.

A person wearing a face mask walks outside of a shopping mall in Beijing on March 11.

Police officers restrain the relative of an inmate outside the Sant'Anna jail in Modena, Italy, on March 9. Riots broke out in several Italian jails after visits were suspended to curb the spread of the coronavirus.

Medical staff in Wuhan, China, celebrate after all coronavirus patients were discharged from a temporary hospital on March 9.

Traders work on the floor of the New York Stock Exchange on March 9. Stocks plummeted as coronavirus worries and an oil price race to the bottom weighed on global financial markets.

Rescuers search for victims at the site of a collapsed hotel in Quanzhou, China, on March 8. The hotel was being used as a coronavirus quarantine center.

The Grand Princess cruise ship, carrying at least 21 people who tested positive for coronavirus, is seen off the coast of San Francisco on March 8. The ship was being held at sea.

Sumo wrestlers attend a tournament in Osaka, Japan, that was being held behind closed doors because of the coronavirus outbreak.

A couple rides a bicycle at a park in Seoul, South Korea, on March 7.

A volunteer from Blue Sky Rescue uses fumigation equipment to disinfect a residential compound in Beijing on March 5.

Airmen from the California National Guard drop coronavirus testing kits down to the Grand Princess cruise ship off the coast of California on March 5.

Municipal workers are seen at the Kaaba, inside Mecca's Grand Mosque. Saudi Arabia emptied Islam's holiest site for sterilization over coronavirus fears, an unprecedented move after the kingdom suspended the year-round Umrah pilgrimage.

Passengers react as a worker wearing a protective suit disinfects the departure area of a railway station in Hefei, China, on March 4.

Teachers at the Nagoya International School in Japan conduct an online class for students staying at home as a precaution against the spread of coronavirus.

Soldiers spray disinfectant throughout a shopping street in Seoul.

A Muslim worshipper attends a mass prayer against coronavirus in Dakar, Senegal, on March 4. It was after cases were confirmed in the country.

People wear face masks in New York's Times Square on March 3. New York reported its first case of coronavirus two days earlier.

A security guard stands on the Shibuya Sky observation deck in Tokyo on March 3.

US President Donald Trump, flanked by Vice President Mike Pence, left, and Health and Human Services Secretary Alex Azar, speaks during a meeting with pharmaceutical executives and the White House coronavirus task force on March 2. Throughout the meeting, Trump was hyperfocused on pressing industry leaders in the room for a timeline for a coronavirus vaccine and treatment. But experts at the table -- from the administration and the pharmaceutical industry -- repeatedly emphasized that a vaccine can't be rushed to market before it's been declared safe for the public.

Medical staff stand outside a hospital in Daegu, South Korea, on March 1.

Healthcare workers transfer a patient at the Life Care Center in Kirkland, Washington, on March 1. The long-term care facility is linked to confirmed coronavirus cases.

British Prime Minister Boris Johnson visits a London laboratory of the Public Health England National Infection Service.

Tomoyuki Sugano, a professional baseball player on the Yomiuri Giants, throws a pitch in an empty Tokyo Dome during a preseason game on February 29. Fans have been barred from preseason games to prevent the spread of the coronavirus.

Commuters wearing masks make their way to work during morning rush hour at the Shinagawa train station in Tokyo on February 28.

Medical staff transport a coronavirus patient within the Red Cross hospital in Wuhan on February 28.

Inter Milan plays Ludogorets in an empty soccer stadium in Milan, Italy, on February 27. The match was ordered to be played behind closed doors as Italian authorities continue to grapple with the coronavirus outbreak.

A bank clerk disinfects banknotes in China's Sichuan province on February 26.

A child wearing a protective face mask rides on a scooter in an empty area in Beijing.

A Catholic devotee wears a face mask as he is sprinkled with ash during Ash Wednesday services in Paranaque, Philippines, on February 26.

People disinfect Qom's Masumeh shrine in Tehran, Iran, on February 25.

A worker in Daegu stacks plastic buckets containing medical waste from coronavirus patients on February 24.

Paramedics carry a stretcher off an ambulance in Hong Kong on February 23.

People attend a professional soccer match in Kobe, Japan, on February 23. To help stop the spread of the novel coronavirus, the soccer club Vissel Kobe told fans not to sing, chant or wave flags in the season opener against Yokohama FC.

A team of volunteers disinfects a pedestrian bridge in Bangkok, Thailand.

A man rides his bike in Beijing on February 23.

Hospital personnel in Codogno, Italy, carry new beds inside the hospital on February 21. The hospital is hosting some people who have been diagnosed with the novel coronavirus.

Doctors look at a CT scan of a lung at a hospital in Xiaogan, China, on February 20.

A sales clerk wears a mask as she waits for customers at a hat shop in Beijing on February 18. Small companies that help drive China's economy are worried about how much damage the coronavirus outbreak will cause to business.

Buses carrying American passengers arrive at the Haneda Airport in Tokyo on February 17. The passengers were leaving the quarantined Diamond Princess cruise ship to be repatriated to the United States.

A medical worker rests at the isolation ward of the Red Cross hospital in Wuhan on February 16.

Authorities watch as the Westerdam cruise ship approaches a port in Sihanoukville, Cambodia, on February 13. Despite having no confirmed cases of coronavirus on board, the Westerdam was refused port by four other Asian countries before being allowed to dock in Cambodia.

A worker has his temperature checked on a shuttered commercial street in Beijing on February 12.

Beds are made in the Wuhan Sports Center, which has been converted into a temporary hospital.

A child rides a scooter past a police officer wearing protective gear outside the Hong Mei House in Hong Kong on February 11. More than 100 people evacuated the housing block after four residents in two different apartments tested positive for the coronavirus.

Relatives of quarantined passengers wave at the Diamond Princess cruise ship as it leaves a port in Yokohama, Japan, to dump wastewater and generate potable water. Dozens of people on the ship were infected with coronavirus.

The Deneway branch of the County Oak Medical Centre is closed amid coronavirus fears in Brighton, England, on February 11. Several locations in and around Brighton were quarantined after a man linked to several coronavirus cases in the United Kingdom came into contact with health-care workers and members of the public.

A police officer, left, wears protective gear as he guards a cordon at the Hong Mei House in Hong Kong on February 11.

A worker wears a protective suit as he waits to screen people entering an office building in Beijing on February 10. China's workforce is slowly coming back to work after the coronavirus outbreak forced many parts of the country to extend the Lunar New Year holiday by more than a week.

Chinese President Xi Jinping has his temperature checked during an appearance in Beijing on February 10.

Photojournalists wearing face masks take photos of a bus carrying passengers after they disembarked from the World Dream cruise ship in Hong Kong on February 9. More than 5,300 people were quarantined on two cruise ships off Hong Kong and Japan.

People participating in a Lunar New Year Parade in New York City hold signs reading, "Wuhan stay strong!" on February 9.

A shopper walks past empty shelves at a grocery store in Hong Kong on February 9. China's Ministry of Commerce encouraged supermarkets and grocery stores to resume operations as the country's voluntary or mandatory quarantines began to take an economic toll.

A worker wearing a protective suit uses a machine to disinfect a business establishment in Shanghai, China, on February 9.

Workers in protective gear walk near the Diamond Princess cruise ship docked in Yokohama on February 7.

People in Hong Kong attend a vigil February 7 for whistleblower doctor Li Wenliang. Li, 34, died in Wuhan after contracting the virus while treating a patient.

A woman grieves while paying tribute to Li at Li's hospital in Wuhan on February 7.

The Anthem of the Seas cruise ship is seen docked at the Cape Liberty Cruise Port in Bayonne, New Jersey, on February 7. Passengers were to be screened for coronavirus as a precaution, an official with the Centers for Disease Control and Prevention told CNN.

A light installation is displayed by striking members of the Hospital Authority Employees Alliance and other activists at the Hospital Authority building in Hong Kong on February 7.

Passengers are seen on the deck of the Diamond Princess cruise ship, docked at the Yokohama Port on February 7.

Flight attendants wearing face masks make their way through Don Mueang Airport in Bangkok on February 7.

Workers check sterile medical gloves at a latex-product manufacturer in Nanjing, China, on February 6.

A woman wears a protective mask as she shops in a Beijing market on February 6.

This aerial photo shows the Leishenshan Hospital that is being built in Wuhan to handle coronavirus patients.

A passenger shows a note from the World Dream cruise ship docked at the Kai Tak cruise terminal in Hong Kong on February 5.

A mask is seen on a statue in Beijing on February 5.

An ambulance stops at a traffic light in front of the Grand Lisboa Hotel in Macao. The virus turned China's gambling mecca into a ghost town.

A dog in Beijing wears a makeshift mask constructed from a paper cup.

Striking hospital workers in Hong Kong demand the closure of the border with mainland China on February 4.

The Diamond Princess cruise ship sits anchored in quarantine off the port of Yokohama on February 4. It arrived a day earlier with passengers feeling ill.

A medical worker wearing protective gear waits to take the temperature of people entering Princess Margaret Hospital in Hong Kong on February 4.

Medical workers in protective suits help transfer patients to a newly completed field hospital in Wuhan.

People wearing protective overalls talk outside a Wuhan hotel housing people in isolation on February 3.

A man stands in front of TV screens broadcasting a speech by Hong Kong Chief Executive Carrie Lam on February 3. Lam said the city would shut almost all border-control points to the mainland.

A colleague sprays disinfectant on a doctor in Wuhan on February 3.

Commuters in Tokyo walk past an electric board displaying dismal stock prices on February 3, the first business day after the Chinese New Year. Asia's markets recorded their worst day in years as investors finally got a chance to react to the worsening coronavirus outbreak.

Medical workers move a coronavirus patient into an isolation ward at the Second People's Hospital in Fuyang, China, on February 1.

Children wear plastic bottles as makeshift masks while waiting to check in to a flight at the Beijing Capital Airport on January 30.

Passengers in Hong Kong wear protective masks as they wait to board a train at Lo Wu Station, near the mainland border, on January 30.

A volunteer wearing protective clothing disinfects a street in Qingdao, China, on January 29.

Nanning residents line up to buy face masks from a medical appliance store on January 29.

Lyu Jun, left, a member of a medical team leaving for Wuhan, says goodbye to a loved one in Urumqi, China, on January 28.

A charter flight from Wuhan arrives at an airport in Anchorage, Alaska, on January 28. The US government chartered the plane to bring home US citizens and diplomats from the American consulate in Wuhan.

South Korean President Moon Jae-in wears a mask to inspect the National Medical Center in Seoul on January 28.

Hong Kong Chief Executive Carrie Lam, center, attends a news conference in Hong Kong on January 28. Lam said China will stop individual travelers to Hong Kong while closing some border checkpoints and restricting flights and train services from the mainland.