While Johnson & Johnson has said it would begin Phase I trials by September at the latest, that now appears likely to be sped up considerably, officials said. Phase I focuses on testing for safety, a particularly important factor for vaccines since they are administered widely to healthy people.
Several of the companies said that they did not want to speak ahead of any announcement by the White House, and the others did not respond to requests for a comment. Along with Moderna, Merck, Pfizer and Johnson & Johnson are based in the United States. AstraZeneca is based in Britain.
Under the administration plan, according to officials, around 30,000 people will take part in Phase III trials for each vaccine when they reach that stage. If all five companies reach Phase III trials, around 150,000 people, mostly Americans, would ultimately become the test subjects for a vaccine.
All age groups will be covered, including older people and those with underlying health conditions.
It is possible, officials and corporate executives in several of the firms said, that some of the Phase III trials will be conducted outside the United States, and may be focused on coronavirus hot spots, where a greater possibility of infection could speed the process of determining the effectiveness of a potential vaccine. The other alternative — deliberately exposing inoculated volunteers to the disease — is fraught with ethical issues and officials seem reluctant to take that route, even if it might speed results.
The plans are being assembled in an office suite on the seventh floor of the Department of Health and Human Services’s headquarters, where two newly appointed leaders of the project, Dr. Moncef Slaoui and Gen. Gustave F. Perna, have set up temporary offices.
Dr. Slaoui comes from the pharmaceutical and venture capital worlds. General Perna heads the Army Matériel Command and is an expert in complex logistics but not medicine.
Their work is monitored by Mr. Azar, Defense Secretary Mark T. Esper and Jared Kushner, the president’s son-in-law and senior adviser. They are coordinating with the senior infectious disease experts on the White House’s coronavirus task force, Dr. Fauci and Dr. Deborah L. Birx, who is overseeing the task force’s day-to-day operations.