The F.D.A. ended its really helpful pause on the J.&J. vaccine, clearing the way in which for states to make use of it once more.

She said the CDC spoke to health care providers for young women, including the American College of Obstetricians and Gynecologists. The hiatus and investigation into the rare disorder, she added, should give the public confidence in the vaccine safety monitoring system.

Almost 8 million doses of the Johnson & Johnson vaccine have now been given. There was less than one case per million doses in men and women aged 50 and over.

About 10 million doses or more of the Johnson & Johnson vaccine, made at the company’s factory in the Netherlands, are on shelves in the United States and could be used immediately. Several states, including Texas, Alabama, Utah, and Wisconsin, said they would likely follow the CDC and FDA recommendations once the decision was made.

Dr. Walensky said she had heard from the governors a keen interest in resuming the use of the shot.

“They wondered why we were on pause and they were eager to have this back, to have an opportunity for a single-dose vaccine, for a one-off opportunity,” she said.

The vaccine has immense potential benefits. If vaccinations are restarted for all adults, 26 to 45 cases of the bleeding disorder are expected in the next six months. This is based on a model developed by CDC scientist Dr. Sara Oliver presented at the meeting on Friday. However, 600 to 1,400 fewer Covid-19-related deaths would be expected over the same period.

The vaccine, which is easy to store and only requires one shot, is also great for hard-to-reach populations, including people who are at home, homeless, or incarcerated.

Other potential cases of the coagulation disorder, including some in men, are currently being investigated. Dr. Shimabukuro also mentioned a case that developed in a 25-year-old man who was taking part in a clinical trial of the vaccine.