While the antibodies declined slightly at 3 months, all participants showed elevated levels.
In a Letter to the Editor published today in the New England Journal of Medicine, investigators studying the Moderna COVID-19 vaccine, mRNA-1273, said virus neutralizing antibodies remained elevated in all the participants 3 months after the booster vaccination.
The vaccine, administered at the 100-μg dosage, was shown to produce high levels of binding and neutralizing antibodies that declined slightly over time.
“At the day 119 time point, the geometric mean titer (GMT) was 235,228 (95% confidence interval [CI], 177,236 to 312,195) in participants 18 to 55 years of age, 151,761 (95% CI, 88,571 to 260,033) in those 56 to 70 years of age, and 157,946 (95% CI, 94,345 to 264,420) in those 71 years of age or older,” the investigators wrote.
The investigators said that while lasting protection against the virus is unknown, the Moderna vaccine may offer long-term immunity.
“These results show that despite a slight expected decline in titers of binding and neutralizing antibodies, mRNA-1273 has the potential to provide durable humoral immunity,” they wrote.
They also stated participants did not suffer any serious adverse events during the trial or after day 57.
The Moderna vaccine is a nucleoside-modified messenger RNA (mRNA) platform that is encoded for a prefusion stabilized form of the SARS-CoV-2 spike protein.
The company announced earlier this week it was going to submit its vaccine to the US Food and Drug Administration (FDA) for an Emergency Use Authorization (EUA). Its meeting is scheduled for December 17, and a potential approval could happen shortly thereafter.