A panel of independent experts to the C.D.C. says it needs more time to assess data and risks during the Johnson & Johnson vaccine pause.

An advisory committee for the Centers for Disease Control and Prevention met on Wednesday to discuss the decision made on Tuesday to pause use of the Johnson & Johnson Covid-19 vaccine because of its possible link to extremely rare blood clots. After a robust afternoon discussion, the panel decided they needed more time to assess the data and risks, and would not vote on a recommendation until they meet again in a week or 10 days.

The emergency meeting followed the Food and Drug Administration’s announcement on Tuesday that it was studying six cases of rare and severe blood clots in women aged 18 to 48, one of whom died. All of the women had received the Johnson & Johnson vaccine before developing the clots, though it is unclear whether the vaccine is responsible. As of Tuesday, more than seven million people in the United States have received the shot, and another 10 million doses have been shipped out to the states, according to C.D.C. data.

Following the call from federal health agencies on Tuesday, all 50 states, Washington, D.C., and Puerto Rico on Tuesday quickly paused or recommended that providers pause the administration of the vaccine. The U.S. military, federally run vaccination sites, and a host of private companies, including CVS, Walgreens, Rite Aid, Walmart and Publix also paused the injections.

The Advisory Committee on Immunization Practices, or ACIP, is a panel of independent experts who advise the C.D.C. on its vaccine policies. At the meeting, the experts reviewed and debated data from the rare blood clots, including a seventh case, and heard comments from the public, before voting on how to proceed.

The clotting disorder of concern in the vaccine recipients is different — and much rarer — than typical blood clots, which develop in hundreds of thousands of people every year. The seven women had not only clotting in the brain, but a notably low level of platelets, parts of the blood that help form normal clots. Three had large, dangerous clots in other parts of their body as well as in the brain.

Use of the vaccine began on Mar. 2, and the first case of blood clots in the brain was reported on Mar. 19. About 1.4 million women ages 20 to 50 — the age range of those who had the clots — received the vaccine.

The panel experts discussed the known background rates of each condition in the general population, but noted that there is not enough data to precisely estimate how often they occur at the same time.

But based on somewhat rough estimates, the clotting disorder in women ages 20 to 50 who received the Johnson & Johnson vaccine occurred at least three times more often than would be expected, according to Dr. Tom Shimabukuro, a safety expert from the C.D.C.

“Right now, we believe these events to be extremely rare, but we are also not yet certain we have heard about all possible cases, as this syndrome may not be easily recognized as one associated with the vaccine,” Dr. Rochelle P. Walensky, the C.D.C. director, said at a White House news conference on the pandemic on Wednesday.

During the panel discussion, one expert reminded the panel that the “risk window” for the condition among vaccine recipients was still open and new cases might emerge, because nearly 3.8 million people had received the shot within the last two weeks.

Other experts encouraged dissemination of health information on diagnosis and treatment of the condition, so that awareness would be spread among doctors, emergency rooms and people who received the vaccine. They noted that patients with the condition need to be treated as soon as possible because the clots are so serious. Some patients needed invasive procedures to remove large clots from blood vessels in their brains.

The committee’s assessment comes at a crucial time, while the nation is racing to vaccinate as many people as possible to curb the steady accumulation of cases, particularly as worrisome variants gain traction. Some public health experts were disappointed in the F.D.A.’s recommendation to suspend the Johnson & Johnson vaccine, arguing that preventing these extremely rare potential side effects was not worth the trade-off of slowing the vaccination campaign and potentially eroding the public’s trust of vaccines in general.

So far, Johnson & Johnson’s vaccine has amounted to about 5 percent of immunizations in the United States. Several panel members reiterated that two other vaccines — from Moderna and Pfizer-BioNTech — are available, neither associated with the clotting problem, so continuing the pause would not stop most people in the United States from being vaccinated.

At the news conference, Jeffrey D. Zients, the White House’s pandemic coordinator, said that the pause would not generally interrupt the momentum of the country’s vaccination campaign.

“In the very short term, we do expect some impact on daily averages as sites and appointments transition from Johnson & Johnson to Moderna and Pfizer vaccines,” he said. “We have more than enough Pfizer and Moderna vaccine supply to continue or even accelerate the current pace of vaccinations.”

Noah Weiland and Madeleine Ngo contributed reporting.