A teacher of the Melissa Bassi school takes the COVID-19 serological test in a medical centre in Rome, Wednesday, Sept. 2, 2020. All teachers are supposed to be tested before the start of the school year. (Cecilia Fabiano/LaPresse via AP)

In this Sunday, Aug. 9, 2020, photo, a hand-painted sign at a post office keeps score of the COVID-19 cases and deaths in the village of Truchas, New Mexico. Nearby wilderness areas and logging roads have allowed residents to hunker down with family cookouts and outdoor recreation. (AP Photo/Cedar Attanasio)

Teacher Lise Genrault looks at a schoolchild washing his hands at the Roissy-en-Brie elementary school, outside Paris, Tuesday, Sept.1, 2020. Millions of French children starting going back to class Tuesday despite a recent rise in virus infections, in a nationwide experiment aimed at bridging inequalities and reviving the economy. (AP Photo/Jeffrey Schaeffer)

Pupils wash their hands at Outwood Academy Adwick in Doncaster, as schools in England reopen to pupils following the coronavirus lockdown, Wednesday, Sept. 2, 2020. Millions of children are returning to school across Europe and beyond in a mass experiment aimed at bridging inequalities and resuscitating economies despite the persistent pandemic. Governments are trying to show that life goes on despite a virus that has infected at least 25 million people worldwide and killed more than 850,000. (Danny Lawson/PA via AP)

Britain's Prime Minister Boris Johnson leaves Downing Street in London, Wednesday, Sept. 2, 2020. The Prime Minister will attend the first session of Prime Ministers Questions since parliament returned Tuesday after the summer break. (AP Photo/Kirsty Wigglesworth)

Minnesota Gov. Tim Walz answers questions during a press conference Tuesday, Aug. 4, 2020, during a stop at Central Minnesota Council on Aging offices in Sartell, Minn. (Dave Schwarz/The St. Cloud Times via AP)

A member of a Chinese medical delegation pushes boxes of vaccines upon arrival to Jorge Chavez airport in Lima, Peru, Wednesday, Sept. 2, 2020. Experimental vaccines for the new coronavirus from the Chinese pharmaceutical company Sinopharm arrived to be injected into people as part of the third phase of a clinical trial, according to China’s Ambassador to Peru, Liang Yu. (AP Photo/Cesar Barreto)

Amelia Wheeler of the United Campus Workers speaks during a "Don't Starve Fight Day of Action" demonstration and food drive at City Hall on Tuesday, Sept. 1, 2020, in Athens, Ga. Demonstrators called on Sen. Kelly Loeffler R-Ga., and other politicians to act and protect workers' lives and livelihoods by extending the $600 unemployment benefit which ended in July. (Joshua L. Jones/Athens Banner-Herald via AP)

FILE - In this Aug. 7, 2020 file photo, people congregate at One-Eyed Jack's Saloon during the 80th annual Sturgis Motorcycle Rally in Sturgis, S.D.. Hundreds of thousands of people attended the Sturgis Motorcycle Rally in South Dakota from Aug. 7 to 16. Minnesota health officials reported Wednesday, Sept. 2, 2020, that a man in his 60s who attended the rally died from COVID-19. (AP Photo/Stephen Groves File)

FILE - In this Nov. 6, 2012 file photo, Silvio Berlusconi, left, sits next to businessman Flavio Briatore, and former AC Milan CEO Adriano Galliani, right as he attends a match t the San Siro stadium in Milan, Italy. Italy’s former prime minister and right-wing leader Silvio Berlusconi has tested positive to coronavirus after a precautionary check, his press office said on Wednesday, Sept. 2, 2020. The three-time-premier and media tycoon had been recently seen with his old-time friend and businessman Flavio Briatore, who was recently hospitalized after testing positive to Covid-19 last month. Berlusconi had tested negative at the time. (AP Photo/Antonio Calanni)

Coronavirus sniffer dogs are seen after being introduced at the Evidensia veterinary clinic in Vantaa, Finland on Wednesday, Sept. 2, 2020. The dogs are trained to detect coron virus from the arriving passengers at the Helsinki-Vantaa international airport. (Antti Aimo-Koivisto/Lehtikuva via AP)

Coronavirus sniffer dogs are seen after being introduced at the Evidensia veterinary clinic in Vantaa, Finland on Wednesday, Sept. 2, 2020. The dogs are trained to detect coron virus from the arriving passengers at the Helsinki-Vantaa international airport. (Antti Aimo-Koivisto/Lehtikuva via AP)

Teachers and students arrive to participate in an outdoor learning demonstration to display methods schools can use to continue on-site education during the coronavirus pandemic, Wednesday, Sept. 2, 2020, at P.S. 15 in the Brooklyn borough of New York. (AP Photo/John Minchillo)

People wearing face masks to protect against the coronavirus walk along a street in the central business district in Beijing, Wednesday, Sept. 2, 2020. Even as China has largely controlled the outbreak, the coronavirus is still surging across parts of the world. (AP Photo/Mark Schiefelbein)

FILE - In this April 11, 2018, file photo, actor Dwayne Johnson poses for photographers at the premiere of the "Rampage," in London. Johnson will host and Justin Bieber, Miley Cyrus and Jennifer Hudson will perform on a globally broadcast concert calling on world leaders to make coronavirus tests and treatment available and equitable for all. The advocacy organization Global Citizen and the European Commission announced Monday, June 22, 2020 that Global Goal: Unite for Our Future — The Concert will air on June 27. (Photo by Vianney Le Caer/Invision/AP, File)

A man wearing a mask to curb the spread of the coronavirus, holds a child on an overlook at the Mount of Olives as they watch the sun set behind the Dome of the Rock Mosque in Jerusalem, Wednesday, Sept. 2, 2020. (AP Photo/Maya Alleruzzo)

A temporary mainland Chinese Huo-Yan laboratory is set up for mass testing at Sun Yat Sen Memorial Park Sports Centre in Hong Kong, Thursday, Sept. 3, 2020. Hong Kong has tested more than 120,000 people for the coronavirus at the start of a mass-testing effort that's become another political flash point in the semi-autonomous Chinese territory. Volunteers stood in lines at testing centers to participate in the government initiative, though many residents are distrustful of the resources and staff being provided by China's central government and some fear DNA could be collected. (AP Photo/Kin Cheung)

The reflection of the Palm Beach County Vice-Mayor Robert Weinroth, left, is seen in a plexiglass coronavirus shield next to Mayor Dave Kerner during a Commission hearing on a possible easing of COVID-19 restrictions to phase two, Tuesday, Sept. 1, 2020, in West Palm Beach, Fla. (Joe Cavaretta/South Florida Sun-Sentinel via AP)

FILE - This July 18, 2020, file photo, shows the AstraZeneca offices in Cambridge, England. AstraZeneca announced Monday, Aug. 31, its vaccine candidate has entered the final testing stage in the U.S. The company said the study will involve up to 30,000 adults from various racial, ethnic and geographic groups. (AP Photo/Alastair Grant, File)

FILE - In this Monday, Aug. 3, 2020 file photo, teacher Francie Keller welcomes the pupils of class 3c of the Lankow primary school on their first school day after the summer holidays in Schwerin, Germany. Despite a spike in virus infections, European authorities are determined to send children back to school. (Jens Buettner/DPA via AP, file)