A healthcare clinician prepares a dose of the Johnson & Johnson vaccine for the coronavirus disease (COVID-19) for a commuter during the opening of MTA’s public vaccination program at the 179th Street subway station in the Queens borough of New York City, New York, U.S., May 12, 2021. REUTERS/Shannon StapletonOct 15 (Reuters) – Some members of an advisory panel to the U.S. Food and Drug Administration on Friday raised questions about the efficacy of Johnson & Johnson’s (JNJ.N) single-shot COVID-19 vaccine and suggested a second dose was needed to better protect those who received it.The panel will vote later on Friday on whether to recommend authorization of a booster shot of J&J’s vaccine for people aged 18 and older, as well as the appropriate interval between the two doses.The advisers are considering whether to recommend a booster shot be given at least two months or at least six months after the first dose. The FDA is not bound to follow their recommendations, but typically does.After hearing presentations on booster options from J&J and FDA scientists, members of the advisory panel asked if the company’s vaccine should actually be considered a two-dose shot for everyone, like the other COVID-19 vaccines authorized for use in the United States.They pointed to lower levels of virus neutralizing antibodies the single shot provokes compared to two-shot vaccines using messenger RNA technology from Moderna Inc (MRNA.O) and Pfizer Inc (PFE.N) with partner BioNTech SE .”What we’re seeing is this is a group with overall lower efficacy than we have seen with the mRNA vaccine, and so there is some urgency to do something,” said Dr. Arnold Monto, an epidemiologist at the University of Michigan’s School of Public Health who chaired the meeting.Dr. Eric Rubin, an infectious disease expert at the Harvard Chan School of Public Health said, “If the vaccine isn’t adequate, it should be boosted and everybody should get it.”J&J scientists said their vaccine was more durable than the mRNA vaccines.Dr. Dan Barouch, a Harvard vaccine researcher who helped design J&J’s COVID-19 vaccine, presented data from a study published on Friday in the New England Journal of Medicine. It found antibody levels from the J&J vaccine were “substantially lower” than the two mRNA vaccines, but that the immune responses remained durable, “with little evidence of decline for over eight months.”Dr. Peter Marks, director of the FDA’s Center for Biologics Evaluation and Research, raised concerns that the data presented by J&J did not reflect all of the information on the vaccine’s performance.”There are some real challenges here. All of the data do not fully align with this being a vaccine that retains excellent activity over time, against all forms of disease or even against severe forms of disease,” Marks said.If the FDA signs off on the boosters, the U.S. Centers for Disease Control and Prevention will make specific recommendations on who should get the shots. CDC advisers are scheduled to meet to discuss the boosters next week.At Friday’s meeting, the panel will also discuss the merits of mixing vaccines from different manufacturers, so that an individual would get a booster that was not the same as their initial inoculation.J&J scientist Dr. Johan Van Hoof said it was difficult to be conclusive about the benefits and risks of mixing the vaccines, and said evidence supported J&J vaccine recipients getting a second dose of the same vaccine.On Thursday, the panel unanimously backed booster shots of Moderna’s COVID-19 vaccine for Americans aged 65 and older and those at high risk of severe illness or occupational exposure to the virus.The U.S. health agencies authorized boosters of the Pfizer/BioNTech vaccine last month.U.S. health officials have been under pressure to authorize the additional shots after the White House announced plans in August for a widespread booster campaign pending approvals from the FDA and the CDC.Reporting by Manojna Maddipatla in Bengaluru; Editing by Caroline Humer, Chizu Nomiyama and Bill BerkrotOur Standards: The Thomson Reuters Trust Principles.