A man wearing a face mask to prevent the spread of the novel coronavirus disease (COVID-19), walks inside a subway station near a Chinese national flag, on the day of the opening session of the National People's Congress (NPC), in Beijing, China May 22, 2020. REUTERS/Tingshu Wang

People wearing face masks to prevent the spread of the novel coronavirus disease (COVID-19), walk inside a subway station near a Chinese national flag, on the day of the opening session of the National People's Congress (NPC), in Beijing, China May 22, 2020. REUTERS/Tingshu Wang

A staff member of the subway station, wearing a face mask, works behind a plastics curtain due to the outbreak of the coronavirus disease (COVID-19), in Tokyo, Japan, May 21, 2020.REUTERS/Kim Kyung-Hoon

U.S. Senator Chuck Grassley (R-IA) reacts to questions from reporters in the Senate subway as he heads to a closed Senate Republican policy lunch meeting with President Donald Trump to discuss the response to the coronavirus disease (COVID-19) outbreak on Capitol Hill in Washington, U.S., May 19, 2020. REUTERS/Yuri Gripas

U.S. Senator Susan Collins (R-ME) talks with Senator Chuck Grassley (R-IA) in the Senate subway as they head to a closed Senate Republican policy lunch meeting to discuss the response to the coronavirus disease (COVID-19) outbreak with senators on Capitol Hill in Washington, U.S., May 19, 2020. REUTERS/Yuri Gripas

A discarded mask lays on a sign in the Capitol subway in Washington, U.S., May 14, 2020. REUTERS/Erin Scott

Morning commuters are seen at the subway station, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

A sign hangs across the entrance to a subway station indicating that the subway is closed for cleaning, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

A conductor looks out of an MTA subway car at a stop, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid TPX IMAGES OF THE DAY

A passenger sleeps inside an MTA subway car, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

A morning commuter waits for the subway, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

A morning commuter waits for the subway, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

Morning commuters wait for the subway, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

Morning commuters wait for the subway, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

A sign hangs across the entrance to a subway station indicating that the subway is closed for cleaning, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

Morning commuters wait for the subway, during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 14, 2020. REUTERS/Brendan McDermid

Karen Miranda, a nurse who works in the coronavirus disease (COVID-19) intensive care unit where patients infected with the COVID-19 are treated at Juarez hospital, takes the subway to get home after her shift, in Mexico City, Mexico May 7, 2020. Picture taken May 7, 2020. REUTERS/Carlos Jasso

Karen Miranda, a nurse who works in the coronavirus disease (COVID-19) intensive care unit where patients infected with the COVID-19 are treated at Juarez hospital, walks towards the subway to get home after her shift, in Mexico City, Mexico May 7, 2020. Picture taken May 7, 2020. REUTERS/Carlos Jasso

Karen Miranda, a nurse who works in the coronavirus disease (COVID-19) intensive care unit where patients infected with the COVID-19 are treated at Juarez hospital, walks towards the subway to get home after her shift, in Mexico City, Mexico May 7, 2020. Picture taken May 7, 2020. REUTERS/Carlos Jasso

French Transport Minister Jean-Baptiste Djebbari visits a subway station control room, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

President of Paris city's RATP transport services Catherine Guillouard and Transport Minister Jean-Baptiste Djebbari visit a subway station control room, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

French Transport Minister Jean-Baptiste Djebbari visits a subway station control room, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

French Transport Minister Jean-Baptiste Djebbari visits a subway station control room, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

Paris Public Transport (RATP) employees prepare to give alcoholic gel to commuters at a subway station, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

President of Paris city's RATP transport services Catherine Guillouard and Transport Minister Jean-Baptiste Djebbari visit a subway station, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

President of Paris city's RATP transport services Catherine Guillouard and Transport Minister Jean-Baptiste Djebbari sanitize their hands before entering a subway station, as the country began easing lockdown restrictions amid the coronavirus disease (COVID-19) outbreak, in Paris, France May 11, 2020. Rafael Yaghobzadeh/Pool via REUTERS

People wearing face masks walk inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks use the staircase inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks walk inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks walk inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks use the stairs and escalator inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks walk inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks walk inside a subway station during morning rush hour, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 11, 2020. REUTERS/Carlos Garcia Rawlins

Social distancing markers reading "healthy distance" are pictured on the floor before passengers boarding the train inside a subway station, as a measure to contain the spread of the coronavirus disease (COVID-19), in Mexico City, Mexico, May 6, 2020. Picture taken May 6, 2020.REUTERS/Edgard Garrido

People wearing face masks exit a subway station during a rainy day, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 8, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks exit a subway station during a rainy day, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 8, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks exit a subway station during a rainy day, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 8, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks exit a subway station during a rainy day, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 8, 2020. REUTERS/Carlos Garcia Rawlins

People wearing face masks exit a subway station during a rainy day, following an outbreak of the coronavirus disease (COVID-19), in Beijing, China May 8, 2020. REUTERS/Carlos Garcia Rawlins

A worker wipes down a handrail as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A cleaner walks on the platform near rows of stationary trains as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

Signage is seen posted on an entrance as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker exits a carriage as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

New York City Police Department (NYPD) officers remove people from the carriage as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

New York City Police Department (NYPD) officers remove a person from a carriage as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

New York City Police Department (NYPD) officers tape up an entrance as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker mops the floor as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker mops the floor as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker wipes down surfaces as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker wipes down surfaces as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker wipes down surfaces as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker wipes down surfaces as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Brooklyn borough of New York City, U.S., May 7, 2020. REUTERS/Andrew Kelly

A worker sprays an escalator handrail as the MTA Subway closed overnight for cleaning and disinfecting during the outbreak of the coronavirus disease (COVID-19) in the Manhattan borough of New York City, U.S., May 6, 2020. REUTERS/Andrew Kelly

A passenger wears a protective mask while waiting for a train inside a subway station, as the spread of the coronavirus disease (COVID-19) continues, in Mexico City, Mexico May 6, 2020. REUTERS/Edgard Garrido

A sign that reads "Careful. High Contagion Zone" is pictured inside a subway station, as a measure to contain the spread of the coronavirus disease (COVID-19), in Mexico City, Mexico May 6, 2020. REUTERS/Edgard Garrido

A New York City MTA transit worker cleans a subway car, during the outbreak of the coronavirus disease (COVID-19) in New York City, New York, U.S., May 6, 2020. REUTERS/Jeenah Moon

A passenger sleeps inside an MTA subway car, during the outbreak of the coronavirus disease (COVID-19) in New York City, New York, U.S., May 6, 2020. REUTERS/Jeenah Moon

Closed Coney Island subway station is seen, during the outbreak of the coronavirus disease (COVID-19) in New York City, New York, U.S., May 6, 2020. REUTERS/Jeenah Moon