By Peter Loftus

A federal vaccine advisory panel voted Sunday to add Johnson & Johnson's newly authorized Covid-19 vaccine to the arsenal of preventive weapons against the coronavirus.

The recommendation, by the Advisory Committee on Immunization Practices, that adults may receive J&J's shot now moves to the director of the U.S. Centers for Disease Control and Prevention, who is expected to formalize the policy imminently. It will be the last step in a federal review process before the vaccine reaches wider use.

The committee voted 12-0 with one recusal in favor of wide use of J&J's Covid-19 vaccine.

"In the midst of this tragedy we do have some reason for optimism," said committee member Dr. Matthew Daley, senior investigator at the Institute for Health Research with Kaiser Permanente Colorado. "How very grateful I am that we now have three safe and highly effective vaccines."

The U.S. Food and Drug Administration authorized use of the single-dose shot on Saturday based on its 66% effectiveness at preventing moderate to severe Covid-19 disease in a large study that also showed it was safe.

J&J said after the FDA clearance that it had started to ship doses of its vaccine for allocation and distribution by the federal government. The doses are expected to start reaching vaccine providers in the U.S. in the coming days, with vaccinations starting soon afterward.

It was the third Covid-19 vaccine cleared by the FDA, after the agency's clearance in December of shots from Pfizer Inc. with its partner BioNTech SE and from Moderna Inc.

The addition of the J&J vaccine is expected to boost the mass vaccination campaign aiming to bring the pandemic under control. Demand for the previously authorized vaccines has outpaced supply so far.

More than 75 million of the 96.4 million doses distributed nationwide have been administered, according to the CDC.

J&J expects to ship about four million doses right away, and to deliver another 16 million by the end of March. By the end of June, J&J expects to provide a total of 100 million doses for use in the U.S.

The federal government has purchased the doses and is making them available free to people.

The new supplies should help more people get vaccinated, especially after J&J increases its output. Yet health authorities don't expect the availability of three shots will mean that many people will start having a choice among them anytime soon.

Each of the three authorized shots works well, according to the authorities, who encourage people to get whichever vaccine they can get.

The CDC's vaccine advisory committee members -- physicians, public-health officials and infectious-disease specialists -- discussed the clinical evidence for J&J's vaccine during an online meeting.

Members of the committee generally had favorable comments about the vaccine, but some expressed concerns.

One concern was that in the large clinical trial, J&J's vaccine appeared to be less effective among people age 60 and older who had certain medical conditions such as diabetes and hypertension.

J&J's Macaya Douoguih, head of clinical development and medical affairs with J&J's Janssen pharmaceuticals unit, said those results should be interpreted with caution because they are based on a relatively small number of Covid-19 cases in that subgroup. She said it wasn't in line with the rest of the trial data, which support that the vaccine provides protection.

The efficacy among American Indian and Alaska natives also was lower than the overall efficacy in the study.

Committee members also began to wrestle with the potentially difficult task of comparing the three authorized vaccines and giving guidance about whether people should choose one over the others. The question has arisen partly because the overall efficacy of J&J's vaccine in a large trial was lower than that for Pfizer's and Moderna's from separate trials.

For now, the committee isn't expressing a preference, with members saying it is tough to compare and contrast the vaccines across different trials, and that all three were generally safe and effective.

"We want to make sure the public understands the best vaccine is the one they can get access to," said Dr. Jason Goldman, a liaison to the committee from the American College of Physicians.

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

(END) Dow Jones Newswires

02-28-21 1612ET