"In final analysis" of the study,"the Moderna COVID-19 vaccine showed 93% efficacy, with the efficacy remaining durable through six months after administration of the second dose," Moderna said in a news release.
Pfizer's pre-print paper showed its vaccine's efficacy -- in a trial involving 44,000 volunteers around the world -- peaked at more than 96% from a week to around two months after a second dose, and then appeared to gradually decline to 83.7% four to six months later, according to the paper, which had not yet been peer-reviewed or published in a journal.
Moderna is waiting for dosage data before filing for an emergency use authorization for a booster shot, Moderna president Dr. Stephen Hoge said in Thursday's investor call. Hoge said the yet-to-be-peer-reviewed data showed that 14 days after a 50-microgram booster was administered, antibody titers increased significantly.
The FDA and US Centers for Disease Control and Prevention said at the time Americans don't need third doses quite yet, and that it was not up to companies alone to decide when an additional dose might be needed.