Moderna COVID-19 Vaccine Elicits Immune Response in Older Adults


Moderna’s COVID-19 mRNA vaccine candidate appears to induce as strong an immune response in older adults as in younger adults, according to an interim analysis.

COVID-19 vaccine

Moderna’s coronavirus disease 2019 (COVID-19) vaccine candidate induced immune responses in older adults, according to a second interim analysis of a phase 1 study evaluating safety and immunogenicity.1

Assessing the efficacy and safety of vaccine candidates in older populations is particularly important for COVID-19, since increased incidences of illness and death from the disease have been associated with older age. 

Co-developed by Moderna and investigators from the National Institute of Allergy and Infectious Disease’s (NIAID) Vaccine Research Center, the investigational vaccine, known as mRNA-1273, is an mRNA vaccine against COVID-19 encoding for a prefusion stabilized form of the Spike (S) protein.2

This open-label phase 1 trial is evaluating the safety and immunogenicity of the vaccine in older adults; the interim analysis evaluated a 2-dose vaccination schedule of mRNA-1273 given 28 days apart in 40 healthy adult participants across 2 dose levels (25µg and 100 µg) in 2 age cohorts (ages 56 to 70 years old and ages 71 and older). Results were reported through day 57, or 1 month after the second dose. The study is an extension of Moderna’s phase 1 safety trial, which was first conducted in individuals aged 18 to 55 years old.1

According to the findings, both dose levels were generally well-tolerated in both age cohorts. The investigators reported that immune responses were dose-dependent with the 100 µg dose eliciting higher binding and neutralizing antibody titers, supporting the selection of the 100 µg dose for further study in the phase 3 trial. At both dose levels, after 2 vaccinations, mRNA-1273 induced dose-dependent antibody responses reaching the upper quartile of the distribution of convalescent sera. At day 57, geometric mean titers exceeded the median of those seen in convalescent sera from 41 individuals with confirmed COVID-19 diagnosis.1

Overall, the data showed that the binding- and neutralizing-antibody responses appeared to be similar to those previously reported among vaccine recipients between the ages of 18 and 55 years, the investigators reported.1

The most common adverse effects (AEs) reported were headache, fatigue, myalgia, chills, and pain at the injection site, the majority of which were mild-to-moderate in severity and of self-limited duration. However, 2 severe solicited systemic AEs occurred following the second vaccination: fever in 1 participant in the 56- to 70-age cohort who received the lower dose, and fatigue in 1 participant in the ages 71 and older cohort, who received the higher dose.1

“These interim phase 1 data suggest that mRNA-1273, our vaccine candidate for the prevention of COVID-19, can generate neutralizing antibodies in older and elderly adults at levels comparable to those in younger adults,” Tal Zaks, MD, PhD, chief medical officer at Moderna, said in a statement.2 “Given the increased morbidity and mortality of COVID-19 in older and elderly adults, these data give us optimism in demonstrating mRNA-1273’s protection in this population, which is being evaluated in the Phase 3 COVE study.”

The US government recently entered an agreement with Moderna for the purchase of 100 million doses of mRNA-1273 for $1.5 billion, with the option for the US to buy up to an additional 400 million doses of mRNA-1273 from Moderna.


  1. Anderson EJ, Rouphael NG, Widge AT, et al. Safety and immunogenicity of SARS-CoV-2 mRNA-1273 vaccine in older adults. The New England Journal of Medicine. September 29, 2020. doi: 10.1056/NEJMoa2028436.
  2. Moderna Announces Publication in The New England Journal of Medicine of Interim Results From Older Adult Age Cohorts in Phase 1 Study of its mRNA Vaccine Against COVID-19 (mRNA-1273). News release. Moderna; September 29, 2020. Accessed October 1, 2020.

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