WASHINGTON — A decision on how to resume vaccinating Americans with the Johnson & Johnson coronavirus shot will probably come by Friday, the top U.S. infectious-diseases specialist said, a faster timeline than other health officials have indicated.

“I doubt very seriously if they just cancel” the J&J vaccine, one of three approved for use in the U.S., Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said on NBC’s “Meet the Press,” one of four Sunday talk-show interviews.

It would be surprising “if we don’t have a resumption in some form by Friday,” Fauci said on CBS’ “Face the Nation.” “One of those possibilities would be to bring them back, but to do it with some form of restriction or some form of warning.”

U.S. health officials paused use of the J&J COVID-19 shots while they seek more data on a rare side effect. Six U.S. women who received the shots developed a severe form of blood clotting six to 13 days after vaccination.

On Thursday, public health officials concluded a meeting on the vaccine without a vote. Advisers to the U.S. Centers for Disease Control and Prevention said they lacked adequate information to make recommendations on how to respond to reports of the clots.

The Advisory Committee on Immunization Practices is set to resume on Friday, according to Rochelle Walensky, the agency’s director.

“I would think that we’re not going to go beyond Friday in the extension of this pause,” Fauci said on ABC’s “This Week.”

On Thursday, though, the head of the CDC panel that’s expected to make a recommendation on the whether the J&J shots should resume said more data is needed and that it was possible the pause could last for several weeks.

“If we make a wrong decision about this, it will impact our credibility and credibility of the vaccine safety system,” Jose Romero told Bloomberg News in an interview. “So it’s very important that we get this right.”

Fauci said on CBS that any new guidance on the vaccine “could be” gender-based, “but we don’t know that” yet. “You don’t want to jump ahead of yourself and assume you know the total spectrum of this,” he said.

The six cases under investigation were reported in women between the ages of 18 and 48, raising questions about whether the syndrome primarily affects females or young people generally.

“I do think that there will likely be some sort of warning or restriction or risk assessment,” Fauci said on NBC.

South Africa’s health regulator asked its government on Saturday to lift a pause on the Johnson & Johnson shots provided certain conditions are met.

Separately, Fauci, a top adviser to President Joe Biden, said officials would determine “soon” -- likely by the end of summer -- whether people who’ve been vaccinated against COVID may need to get booster shots or new vaccines aimed at emerging strains.

Officials with vaccine makers Moderna and Pfizer have indicated that a booster dose may be required, or that the COVID-19 vaccines become annual events like flu shots, but Fauci on NBC said that such a call would be a “public health decision.”

“It’s not going to be a decision that’s going to be made by a pharmaceutical company,” he said. “We’re partners with them because they’re supplying it. It’ll be an FDA-CDC decision.”

On CNN, Fauci added that the U.S. will be prepared for coronavirus variants “either by boosting with the current vaccine, or boosting with a variant-specific vaccine.”

(With assistance by Tony Czuczka and Yueqi Yang.)