People queue up at a temporary screening center for COVID-19 PCR tests in front of the city hall of Paris, France, Aug. 31, 2020. COVID-19 screening centers were set up in Paris on Monday, inviting Parisians to free tests after their return from vacation. These temporary centers will be operating in all of the French capital's arrondissements. Coronavirus infections have surged in France in recent weeks, particularly among young people, prompting the government to make mask-wearing mandatory outdoor and at workplace. (Photo by Aurelien Morissard/Xinhua)

A medical worker wearing protective equipment takes a swab sample from a woman for a COVID-19 PCR test at a temporary screening center in front of the city hall of Paris, France, Aug. 31, 2020. COVID-19 screening centers were set up in Paris on Monday, inviting Parisians to free tests after their return from vacation. These temporary centers will be operating in all of the French capital's arrondissements. Coronavirus infections have surged in France in recent weeks, particularly among young people, prompting the government to make mask-wearing mandatory outdoor and at workplace. (Photo by Aurelien Morissard/Xinhua)

People queue up at a temporary screening center for COVID-19 PCR tests in front of the city hall of Paris, France, Aug. 31, 2020. COVID-19 screening centers were set up in Paris on Monday, inviting Parisians to free tests after their return from vacation. These temporary centers will be operating in all of the French capital's arrondissements. Coronavirus infections have surged in France in recent weeks, particularly among young people, prompting the government to make mask-wearing mandatory outdoor and at workplace. (Photo by Aurelien Morissard/Xinhua)

People queue up at a temporary screening center for COVID-19 PCR tests in front of the city hall of Paris, France, Aug. 31, 2020. COVID-19 screening centers were set up in Paris on Monday, inviting Parisians to free tests after their return from vacation. These temporary centers will be operating in all of the French capital's arrondissements. Coronavirus infections have surged in France in recent weeks, particularly among young people, prompting the government to make mask-wearing mandatory outdoor and at workplace. (Photo by Aurelien Morissard/Xinhua)

A medical worker wearing protective equipment takes a swab sample from a man for a COVID-19 PCR test at a temporary screening center in front of the city hall of Paris, France, Aug. 31, 2020. COVID-19 screening centers were set up in Paris on Monday, inviting Parisians to free tests after their return from vacation. These temporary centers will be operating in all of the French capital's arrondissements. Coronavirus infections have surged in France in recent weeks, particularly among young people, prompting the government to make mask-wearing mandatory outdoor and at workplace. (Photo by Aurelien Morissard/Xinhua)