Antibodies elicited by the Moderna COVID-19 vaccine persisted through 6 months after the second dose, according to new data published in The New England Journal of Medicine.  

The study analyzed 33 healthy adult participants in the National Institutes of Health (NIH)-led phase 1 study of the Moderna COVID-19 vaccine at 6 months following the second dose (day 209). Study participants were stratified according to age: 18 to 55 years (n=15); 56 to 70 years (n=9); and 71 years and older (n=9). At day 209, antibody activity was measured using 3 distinct serologic assays (receptor-binding domain ELISA, pseudovirus neutralization assay, live-virus neutralization assay). 

At day 209, results showed that the antibody activity remained high in all age groups; however, the activity declined in older adults when using more sensitive assays. The antibody decay was found to be consistent with published observations of convalescent patients with COVID-19 through 8 months after symptom onset. 

“We are pleased that this new data shows antibody persistence through 6 months following the second dose of our COVID-19 vaccine,” said Stéphane Bancel, CEO of Moderna. ‘This gives us further confidence in the protection afforded by our COVID-19 vaccine.”

Immune responses elicited by the vaccine will continue to be monitored in ongoing studies beyond 6 months. Moderina is also pursuing a clinical development program in response to emerging variants. The Company plans to evaluate variant-specific and multivalent booster vaccine candidates as a primary vaccination series for those who are seronegative. Additionally, the NIH recently announced that a phase 1 trial evaluating the monovalent and multivalent modified Moderna COVID-19 vaccines as a primary series has begun.


1.    Moderna highlights publication of antibody persistence data of its COVID-19 Vaccine out to 6 months in the New England Journal of Medicine. [press release]. Cambridge, MA: Moderna, Inc.; April 7, 2021.

2.    Doria-Rose N, Suthar MS, Makowski M, et al. Antibody persistence through 6 months after the second dose of mRNA-1273 vaccine for Covid-19N Engl J Med. Published online April 6, 2021. doi: 10.1056/NEJMc2103916.