A lab technician works during research on coronavirus, COVID-19, at Johnson & Johnson subsidiary Janssen Pharmaceutical in Beerse, Belgium, Wednesday, June 17, 2020. Janssen Pharmaceutical hopes to begin clinical trials on a potential vaccine for COVID-19 in the middle of the summer. (AP Photo/Virginia Mayo)

FILE - In this Feb. 20, 2020, file photo, a view of the AstraZeneca logo, on a building, in South San Francisco, Calif. As the race for a vaccine against the coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. Britain and the U.S., meanwhile, have each sunk millions of dollars into various vaccine candidates, including one being developed by Oxford University and manufactured by AstraZeneca. (AP Photo/Jeff Chiu, File)

FILE - In this June 16, 2020, file photo, French President Emmanuel Macron listens to researchers as he visits an industrial development laboratory at French drugmaker's vaccine unit Sanofi Pasteur plant in Marcy-l'Etoile, near Lyon, central France, Tuesday. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Laurent Cipriani, Pool, File)

FILE - In this June 16, 2020, file photo, French President Emmanuel Macron listens to a researcher as he visits an industrial development laboratory at French drugmaker's vaccine unit Sanofi Pasteur plant in Marcy-l'Etoile, near Lyon, central France. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Laurent Cipriani, Pool)

FILE - In this June 16, 2020, file photo, French President Emmanuel Macron visits an industrial development laboratory at French drugmaker's vaccine unit Sanofi Pasteur plant in Marcy-l'Etoile, near Lyon, central France. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Laurent Cipriani, Pool, File)

FILE - In this March 16, 2020, file photo, a patient receives a shot in the first-stage safety study clinical trial of a potential vaccine for COVID-19 at the Kaiser Permanente Washington Health Research Institute in Seattle. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Ted S. Warren, File)

FILE - In this May 25, 2020, file photo, a lab technician extracts a portion of a COVID-19 vaccine candidate during testing at the Chula Vaccine Research Center, run by Chulalongkorn University in Bangkok, Thailand. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Sakchai Lalit, File)

FILE - In this March 12, 2020, file photo, a researcher at Protein Sciences reaches for a vial in a lab in Meriden, Conn. The biotech company is currently researching a vaccine for COVID-19. As the race for a vaccine against the new coronavirus intensifies, many rich countries are rushing to the front of the line by placing advance orders for the inevitably limited supply to guarantee their citizens are immunized first. (AP Photo/Jessica Hill, File)