Using prior knowledge of the importance of the coronavirus spike proteins in pathogenesis and immunity as well as the SARS-CoV-2 genetic sequence, researchers at the National Institute of Allergy and Infectious Disease and Moderna (Cambridge, MA) rapidly developed an mRNA vaccine against SARS-CoV-2. This lipid nanoparticle-encapsulated mRNA vaccine candidate (mRNA-1273) contains a portion of the spike glycoprotein subunit S2 (S-2P). As reported in The New England Journal of Medicine, 45 healthy adults (ages 18 to 55 years) were assigned to receive either 25 µg, 100 µg, or 250 µg of the vaccine given as two doses 28 days apart. The mRNA-1273 vaccine induced antibody responses in all participants. Twenty-eight days after the first dose, anti-S-2P geometric mean antibody titers were 40,227 in the 25 µg group, 109,209 in the 100 µg group, and 213,526 in the 250 µg group. A month after the second dose, antibody titers had all increased and were at similar or higher levels as antibody titers in convalescent plasma controls. Minor or mild adverse events (fatigue, chills, headache, myalgia, and pain at the injection site) occurred in over half of participants in the 25 µg group after the second dose and all of the participants in the 100 µg and 250 µg groups. In addition, three participants reported serious adverse events, though no trial-limiting safety concerns were reported. As this promising vaccine candidate moves into phase 2 and phase 3 trials, researchers will continue to evaluate the safety, dosage, immunogenicity, and efficacy.
References:
- Heaton, PM. The Covid-19 vaccine-development multiverse. The New England Journal of Medicine 2020
- Jackson LA, Anderson EJ, Rouphael NG, Roberts PC, et al. An mRNA vaccine against SARS-CoV-2 preliminary report. The New England Journal of Medicine 2020
