Washington D.C. [US], July 31 (Sputnik/ANI): The United States vaccinated several hundred volunteers during the first days of two Phase 3 COVID-19 vaccine trials, senior administration official told reporters.
"Without revealing a lot of numbers, there were several hundred folks who get vaccinated on day one and the last couples of days," the official said on Thursday.
Both trials began on Monday by Moderna and Pfizer companies in cooperation with the National Institutes of Health (NIH) and other federal health organizations, he added.
US government and private companies are building technologies for monitoring COVID-19 vaccine deployment, the official noted.
"This is an extremely dynamic and unpredictable situation. We do not know how well these vaccines are going to work until we finish our clinical trials process," he said.
On July 27, the NIH said that US scientists have begun a phase three trial of a potential COVID-19 vaccine, known as mRNA-1273, developed by Moderna. NIH revealed plans to conduct the trial at multiple US clinical research sites with participation of approximately 30,000 adult volunteers who do not have COVID-19. (Sputnik/ANI)