By Peter Loftus

A federal vaccine advisory committee Friday recommended that use of Johnson & Johnson's Covid-19 vaccine resume in the U.S., while J&J and regulators plan to add language to the product label warning of the potential for a rare blood-clot condition.

If U.S. authorities follow the panel's recommendation, J&J's vaccine could be back in circulation as soon as this weekend, ending a pause that began last week and aiding some vaccination sites that wrestled with limited supplies after the shot was pulled.

"The benefits clearly outweigh the risks, though there are differences in age groups, and particularly for women less than 50 years of age," said Dr. Katherine Poehling, a member of the Advisory Committee on Immunization Practices that made the recommendation, who is also a professor of pediatrics and epidemiology at Wake Forest School of Medicine.

The panel voted 10 to 4, with one abstention, in favor of lifting the recommended pause and restarting use among all adults.

J&J has agreed with the Food and Drug Administration to add language to the vaccine's label warning about the clot risk, J&J Chief Medical Officer Joanne Waldstreicher told members of the vaccine committee during its meeting.

Dr. Waldstreicher said resumption of vaccinations with J&J's shot would likely prevent many more deaths and hospitalizations from Covid-19 than the number of rare clot cases that may occur in people receiving the vaccine.

"We believe the J&J Covid vaccine is central to the effort to end the pandemic," Dr. Waldstreicher said.

A Centers for Disease Control and Prevention official said that if vaccinations with J&J's shot resumed, it could prevent up to 1,400 deaths from Covid-19 and up to 3,500 admissions to hospital intensive-care units over a six-month period, though there could be up to 45 cases of the rare blood-clot condition.

"Lifting the pause on J&J's vaccine is in the best public-health interest of the U.S. population," said committee member Henry Bernstein, who is also professor of pediatrics at the Zucker School of Medicine at Hofstra/Northwell.

After the vote, J&J said the committee vote was an important step toward continuing vaccinations and the company will collaborate with health authorities to ensure the clot condition can be identified early and treated effectively.

J&J vaccine injections were put on hold after reports of a rare blood-clot condition in a small number of recipients, including at least three fatalities.

Many public-health authorities, however, contended that the benefits of the vaccine outweigh the risks. The risk of blood clots is much higher from Covid-19 disease than from the vaccines associated with these complications, Jean Connors, a hematologist at Brigham and Women's Hospital in Boston, said in an interview.

Blood clotting all over the body is one complication of severe forms of the disease. About 15% to 20% of Covid-19 patients who are admitted to intensive-care units develop blood clots, Dr. Connors said.

Agreement by the FDA and CDC to lift the pause could put the vaccine back in circulation as early as this weekend, because millions of doses have already been distributed to vaccine sites.

Its availability could ease supply constraints that some areas and vaccination sites counting on J&J's vaccine have experienced since its use was paused. It could also fulfill demand among people who prefer to get a single shot, rather than two doses spaced weeks apart required for protection from the Pfizer Inc. and Moderna Inc. vaccines.

"I do think that there's plenty of people who are interested in the J&J vaccine, if just for convenience as well as for a single-dose option," CDC Director Rochelle Walensky said at a White House briefing before the vote.

Earlier in the week, Europe's medicines regulator recommended adding warning language to J&J's shot, but said its benefits outweighed its risks.

The Advisory Committee on Immunization Practices -- which advises the CDC on vaccines and includes doctors and public-health officials -- voted following a six-hour meeting. It was the ACIP's second emergency meeting in 10 days to discuss the J&J vaccine.

The committee met April 14, one day after use of J&J's vaccine was paused, but deferred voting on a recommendation because members wanted more information about the vaccine's risks and benefits.

The CDC has now identified a total of 15 cases of women experiencing blood clots combined with low blood-platelet counts after receiving the J&J vaccine, according to a presentation by a CDC official during Friday's ACIP meeting. Three of the women have died.

Two of the cases were in women 50 and older, while the rest were between 18 and 49 years of age. The symptoms, including severe headaches and nausea, started around one to two weeks after vaccination.

The CDC is calling the rare condition "thrombosis with thrombocytopenia syndrome," or TTS.

Most of the women had blood clots in veins that drain blood from the brain, but some had clots only in other parts of the body, according to the CDC's presentation to the ACIP panel during its meeting. The condition is also marked by low levels in the blood of platelets, which play a role in clotting.

The CDC is investigating fewer than 10 potential additional cases of TTS, Tom Shimabukuro, a CDC vaccine-safety official, said during the ACIP meeting.

He also cited one case of a woman who experienced TTS and died, but she was excluded from the case count partly because she also had contracted Covid-19 after receiving the J&J vaccine.

Dr. Shimabukuro said the rare combination of clots with low platelet counts is similar to cases that have been reported in Europe among recipients of AstraZeneca PLC's Covid-19 vaccine. He said this rare condition wasn't seen in people who received the messenger RNA-based vaccines from Pfizer and Moderna.

Though the incidence of the clot risk appears low, some ACIP members expressed concern about its seriousness. "It's not an insignificant risk, " said committee member Pablo Sanchez, who is also a pediatric infectious diseases specialist Nationwide Children's Hospital in Columbus, Ohio. "It makes me nervous."

Some committee members wanted their recommendation Friday to also state that women under 50 should be aware of the clot risk and may choose a different Covid-19 vaccine.

The FDA authorized use of J&J's vaccine in late February, the third Covid-19 shot to be cleared -- after shots from Pfizer with its partner BioNTech SE, and Moderna. J&J's vaccine was cleared for people 18 years and older.

Before the pause, J&J's vaccine made up a relatively small portion of all available Covid-19 vaccine doses, as the company increased production. Nearly eight million doses of J&J's vaccine had been administered at the time of the pause, according to the CDC.

Still, public-health officials view the J&J vaccine as particularly useful in vaccinating hard-to-reach populations, such as the homebound and homeless.

In addition to requiring just one dose, it can be stored in a standard refrigerator for longer periods than the other vaccines.

J&J, of New Brunswick, N.J., has a federal contract to supply about 100 million doses of its vaccine for U.S. use by midyear. J&J has said it is committed to supply that amount, but that production issues at a contract manufacturer's plant in Baltimore could affect timing of the delivery of doses.

Production of J&J's vaccine at the plant recently stopped during an FDA inspection, which identified unsanitary conditions and other problems.

(More to Come)

--Betsy McKay, Eric Sylvers and Tarini Parti contributed to this article.

Write to Peter Loftus at peter.loftus@wsj.com

(END) Dow Jones Newswires

04-23-21 1822ET