This evidence synthesis has been compiled by members of the CITF Secretariat and does not necessarily represent the views of all CITF members.

By Jeanie Quach

The Moderna mRNA-1273 vaccine was previously shown to be 94.1% efficacious at preventing COVID-19 illness in a phase 3 trial of 30,420 volunteers. Drs. Nicole Doria-Rose from the National Institute of Allergy and Infectious Diseases, Mehul S. Suthar from Emory University School of Medicine and collaborators describe the results in an ongoing phase 1 trial published in the New England Journal of Medicine. This trial involving 33 healthy adults showed that antibody levels remained high in all age groups throughout the six months after the second dose of the vaccine.

A total of 33 participants categorized into age groups 18-55, 56-70, and 71 and older received 100 µg of mRNA-1273 on days 1 and 29. They were followed up to six months to determine the levels of binding antibodies and neutralization responses after vaccination. Using an ELISA against SARS-CoV-2 spike receptor-binding protein, IgG antibody titers were similar for all age groups and remained elevated throughout the six months after the second dose of the vaccine. Almost all participants had neutralizing activity, measured using both pseudovirus and live-virus neutralization assays. These levels remained high throughout the six months post-second dose as well. Similar results were observed across all age groups, even in seniors. These findings are consistent with a Science paper and results from CITF-funded researchers Drs. Daniel Kaufmann and Andrés Finzi that showed antibodies persisting in convalescent patients throughout at least eight months after symptom-onset.

Studies are currently ongoing to assess immune responses beyond six months and to determine the effect of a booster dose. The authors conclude that the use of this vaccine is promising as it demonstrated the capacity to generate long-lived neutralizing antibodies.


Doria-Rose N, Suthar MS, Makowski M, O’Connell S, McDermott AB, Flach B, Ledgerwood JE, Mascola JR, Graham BS, Lin BC, O’Dell S, Schmidt SD, Widge AT, Edara V-V, Anderson, EJ, Lai L, Floyd K, Rouphael NG, Zarnitsyna V, Roberts PC, Makhene M, Buchanan W, Luke CJ, Beigel JH, Jackson LA, Neuzil KM, Bennett H, Leav B, Albert J, Kunwar P. Antibody persistence through 6 Months after the second dose of mRNA-1273 vaccine for Covid-19. The New England Journal of Medicine. 6 Apr 2021. doi: 10.1056/NEJMc2103916