A healthcare worker measures body temperature as a precaution against the spread of the new coronavirus in COVID-19 hospital in Sarajevo, Bosnia, Monday, July 27, 2020. Regional WHO office in Bosnia expressed its concern with recent reports that medical institutions around the country are closing to maximum capacity as recent spike in COVID-19 infections are reaching record levels. (AP Photo/Eldar Emric)

People wearing a face mask walk on Las Ramblas in Barcelona, Spain, Monday, July 27, 2020. Britain has put Spain back on its unsafe list and announced Saturday that travelers arriving in the U.K. from Spain must now quarantine for 14 days. (AP Photo/Felipe Dana)

Visitors wear face coverings while walking around Monday, July 27, 2020, in the Mountain tourist town of Georgetown, Colo. (AP Photo/David Zalubowski)

Inmates protest on the roof of a San Sebastian prison, asking for better medical attention amid the pandemic and to be given the results from previously administered COVID-19 tests, in Cochabamba, Bolivia, Monday, July 27, 2020. (AP Photo/Dico Solis)

Workers spray each other with disinfectant solution after unloading the body of a person who died from suspected COVID-19, at the crematorium at Xilotepec Cemetery in Xochimilco, Mexico City, Monday, July 27, 2020. (AP Photo/Rebecca Blackwell)

Nurse Kathe Olmstead, right, gives volunteer Melissa Harting, of Harpersville, N.Y., an injection as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway Monday, July 27, 2020, in Binghamton, N.Y. (AP Photo/Hans Pennink)

Shoppers walk by storefronts while wearing masks to protect against coronavirus, Saturday, July 25, 2020, in Bath, Maine. (AP Photo/Robert F. Bukaty)

Healthcare worker Dante Hills, left, passes paperwork to a woman in a vehicle at a COVID-19 testing site outside of Marlins Park, Monday, July 27, 2020, in Miami. The Marlins home opener against the Baltimore Orioles on Monday night has been postponed as the Marlins deal with a coronavirus outbreak that stranded them in Philadelphia. (AP Photo/Lynne Sladky)

Health workers arrives to screen people for COVID-19 symptoms at a residential building in Mumbai, India, Sunday, July 26, 2020. India is the third hardest-hit country by the pandemic in the world after the United States and Brazil. (AP Photo/Rafiq Maqbool)

Nurse Carolyn Grausgruber gives volunteer Ithaca firefighter Wade Bardo, of Erin, N.Y., an injection as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway Monday, July 27, 2020, in Binghamton, N.Y. (AP Photo/Hans Pennink)

People gather for a demonstration in Prague, Czech Republic, Monday, July 27, 2020. Hundreds of musicians, concert promoters, club owners and other involved in the music industry rallied in Prague's Old Town Square to protest against government restrictions due to the coronavirus pandemic that they say ruin their business. (AP Photo/Petr David Josek)

People sit among photographs of people printed on sheets of paper stuck on seats in order for the audience to social distance, at the Municipal Theater in capital Nicosia, Cyprus, Monday, July 27, 2020. A group of actors are performing a number of short plays dealing with the goings-on during coronavirus lockdown conditions that Cyprus imposed between March and May of this year. (AP Photo/Petros Karadjias)

A woman shops for postcards in town of Sóller in the Balearic Island of Mallorca, Spain, Monday, July 27, 2020. Britain has put Spain back on its unsafe list and announced Saturday that travelers arriving in the U.K. from Spain must now quarantine for 14 days. (AP Photo/Joan Mateu)

Passengers wearing face masks arrive at Son Sant Joan airport on the Spanish Balearic Island of Mallorca, Spain, Monday, July 27, 2020. Britain has put Spain back on its unsafe list and announced Saturday that travelers arriving in the U.K. from Spain must now quarantine for 14 days. (AP Photo/Joan Mateu)

Dr. Frank Eder works in his office as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway Monday, July 27, 2020, in Binghamton, N.Y. (AP Photo/Hans Pennink)

Nurse Kathe Olmstead prepares a shot as the world's biggest study of a possible COVID-19 vaccine, developed by the National Institutes of Health and Moderna Inc., gets underway Monday, July 27, 2020, in Binghamton, N.Y. (AP Photo/Hans Pennink)