HealthDay News — Antibodies persist through six months after the second dose of the Moderna COVID-19 mRNA vaccine, according to a letter to the editor published online April 6 in the New England Journal of Medicine.

On behalf of the mRNA-1273 Study Group, Nicole Doria-Rose, Ph.D., from the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, and colleagues describe mRNA-1273-elicited binding and neutralizing antibodies in 33 healthy adult participants in an ongoing phase 1 trial at 180 days after the second dose of 100 μg of the Moderna COVID-19 vaccine (day 209).

The researchers found that antibody activity remained high in all age groups at day 209. Binding antibodies had geometric mean end-point titers (GMTs) of 92,451 in participants 18 to 55 years of age, 62,424 in individuals 56 to 70 years of age, and 49,373 in those aged 71 years and older. Almost all of the participants had detectable activity in a pseudovirus neutralization assay, with 50 percent inhibitory dilution (ID50) GMTs of 80, 57, and 59, respectively, according to age group. All the participants had detectable activity on the more sensitive live-virus focus-reduction neutralization mNeonGreen test, but the ID50 GMTs were higher in those 18 to 55 years of age (406) than in those 56 to 70 years of age (171) and ages 71 years and older (131).


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“Although the antibody titers and assays that best correlate with vaccine efficacy are not currently known, antibodies that were elicited by mRNA-1273 persisted through six months after the second dose, as detected by three distinct serologic assays,” the authors write.

Several authors disclosed financial ties to Moderna.

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