Safety and Immunogenicity of SARS-CoV-2 mRNA-1273 Vaccine in Older Adults

N Engl J Med. 2020 Dec 17;383(25):2427-2438. doi: 10.1056/NEJMoa2028436. Epub 2020 Sep 29.

Abstract

Background: Testing of vaccine candidates to prevent infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in an older population is important, since increased incidences of illness and death from coronavirus disease 2019 (Covid-19) have been associated with an older age.

Methods: We conducted a phase 1, dose-escalation, open-label trial of a messenger RNA vaccine, mRNA-1273, which encodes the stabilized prefusion SARS-CoV-2 spike protein (S-2P) in healthy adults. The trial was expanded to include 40 older adults, who were stratified according to age (56 to 70 years or ≥71 years). All the participants were assigned sequentially to receive two doses of either 25 μg or 100 μg of vaccine administered 28 days apart.

Results: Solicited adverse events were predominantly mild or moderate in severity and most frequently included fatigue, chills, headache, myalgia, and pain at the injection site. Such adverse events were dose-dependent and were more common after the second immunization. Binding-antibody responses increased rapidly after the first immunization. By day 57, among the participants who received the 25-μg dose, the anti-S-2P geometric mean titer (GMT) was 323,945 among those between the ages of 56 and 70 years and 1,128,391 among those who were 71 years of age or older; among the participants who received the 100-μg dose, the GMT in the two age subgroups was 1,183,066 and 3,638,522, respectively. After the second immunization, serum neutralizing activity was detected in all the participants by multiple methods. Binding- and neutralizing-antibody responses appeared to be similar to those previously reported among vaccine recipients between the ages of 18 and 55 years and were above the median of a panel of controls who had donated convalescent serum. The vaccine elicited a strong CD4 cytokine response involving type 1 helper T cells.

Conclusions: In this small study involving older adults, adverse events associated with the mRNA-1273 vaccine were mainly mild or moderate. The 100-μg dose induced higher binding- and neutralizing-antibody titers than the 25-μg dose, which supports the use of the 100-μg dose in a phase 3 vaccine trial. (Funded by the National Institute of Allergy and Infectious Diseases and others; mRNA-1273 Study ClinicalTrials.gov number, NCT04283461.).

Publication types

  • Clinical Trial, Phase I
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antibodies, Neutralizing / blood
  • Antibodies, Viral / blood
  • COVID-19 / immunology
  • COVID-19 / prevention & control*
  • COVID-19 Vaccines / administration & dosage
  • COVID-19 Vaccines / adverse effects*
  • COVID-19 Vaccines / immunology*
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Male
  • Middle Aged
  • Neutralization Tests
  • SARS-CoV-2 / immunology*
  • Spike Glycoprotein, Coronavirus
  • T-Lymphocytes / physiology

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 Vaccines
  • Spike Glycoprotein, Coronavirus
  • spike protein, SARS-CoV-2
  • mRNA-1273 vaccine

Associated data

  • ClinicalTrials.gov/NCT04283461