Elasomeran (mRNA1273) Vaccine: The Journey from Preclinical Research to Clinical Trials, Authorization, and FDA Approval

The rapid spread of COVID-19 worldwide resulted in critical illness and mortality. Supportive measures have been the center stage for therapy. One crucial question since the onset of the deadly SARS-CoV-2 pandemic was the development of a vaccine. Developed by Moderna, the mRNA1273 vaccine, Elasomeran contains a lipid nanoparticle (LNP) that encapsulates a nucleoside-modified messenger RNA (modRNA), which encodes the spike (S) protein of the SARS-CoV-2 virus. This vaccine is administered as a dual dose regimen 28 days apart (1 month). Seven days following Pfizer's BNT162b2 vaccine, mRNA1273 received FDA-Emergency Use Authorization (EUA) on December 18, 2020, making it the second candidate. During the randomized, placebo-controlled, observer-blinded, phase 3 clinical trials, the mRNA1273 vaccine demonstrated 94.1% efficacy. Clinical trials in children aged 5–12 and adolescents also received FDA-EUA. The Moderna vaccine is also the second vaccine following Pfizer's BNT162b2 vaccine to receive full FDA approval on January 31, 2020, for use in individuals aged 18 and above for COVID-19 prevention. Real-world outcomes have been profoundly positive, reflecting its effectiveness in reducing hospitalization rates, infections, and mortality. This review article encompasses Moderna's vaccine journey, summarizing the mRNA1273 vaccine's preclinical studies, phase 1, phase 2, phase 3 clinical trials, dosages, immune response, adverse effects, FDA-EUA, FDA approval, and real-world outcomes discussing the overall effectiveness of the vaccine in healthy individuals, individuals with pre-existing underlying medical conditions, single-dose effects, delayed second dose, SARS-CoV-2 variants, and mix and match vaccines.