Moderna Vaccine May Be Best Antibody Booster After J&J’s
(Bloomberg) -- U.S. Food and Drug Administration advisers are meeting Friday to consider Johnson & Johnson’s application for authorization of a second booster dose of its Covid-19 shot. An up or down vote is expected by early afternoon.
But the best way to bolster antibodies in people who got J&J’s single-shot vaccine may be to instead give an additional full dose of a messenger RNA vaccine, if a U.S. government-sponsored trial is any indication.
FDA may consider authorization of using one of the U.S.-cleared vaccines to boost initial doses of another, Peter Marks, director of the agency’s Center for Biologics Evaluation and Research, told the panel of advisers. He didn’t give a timeline for when this might happen.
Data from the trial of mixing and matching vaccines with different boosters show that giving a full dose of Moderna Inc.’s shot roughly three months after an initial one from J&J bolsters neutralizing antibodies by an astonishing 76-fold over 15 days. The study is scheduled to be presented to the panel for discussion later this afternoon.
Giving a Pfizer shot after a J&J shot drove a 35-fold increase in the antibodies, according to preliminary trial data. Meanwhile, a second dose of the J&J shot bolstered the antibodies just fourfold.
Johan Van Hoof, managing director of J&J’s Janssen Vaccines & Prevention unit, tried to throw cold water on the whole strategy of matching vaccines with boosters of another brand.
“Questions remain on the efficacy, durability and safety of heterologous boosting,” he told the panel. Boosting with the same vaccine is “preferred,” he said.
Antibodies are just one part of the immune response, and not necessarily the most important for preventing severe Covid disease. Nonetheless, protective antibodies levels were the primary outcome that Pfizer and Moderna studied in their booster shot trials.
Dan Barouch, a Harvard Medical School professor who helped develop the J&J shot, acknowledged that it evoked lower antibody levels compared to messenger RNA vaccines. But he presented data indicating that antibodies elicited by the shot are longer-lasting. The J&J shot also does a good job at producing certain important immune cells, he noted.
A J&J clinical trial also indicates that giving a second dose two months after the first raises vaccine efficacy in the U.S. to around 94% in the short term. While impressive, it’s not clear what these efficacy numbers would mean for U.S. vaccine recipients who received their first J&J shot several months ago.
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