The mRNA-1273 vaccine, known commercially as Spikevax, is Moderna’s vaccine developed to protect against the SARS-CoV-2 virus, which causes COVID-19. This vaccine uses messenger RNA (mRNA) technology to instruct human cells to produce a specific protein from the virus, the spike protein. Once this protein is made, the body’s immune system recognizes it as foreign and generates antibodies to fight off SARS-CoV-2 infection.
Current Global and National Standing
The mRNA-1273 vaccine has received widespread authorization and recommendation from regulatory bodies globally. The U.S. Food and Drug Administration (FDA) granted Emergency Use Authorization (EUA) for mRNA-1273 in December 2020 for individuals 18 and older. Full FDA approval for Spikevax followed in January 2022, expanding to include individuals 12 and older. The European Medicines Agency (EMA) also granted conditional marketing authorization for the vaccine in early 2021.
Public health agencies like the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) guide its use. As of May 2025, the FDA restricted its recommendations for COVID-19 vaccines to adults 65 years and older, and to individuals of all ages with an increased risk for severe disease. This means Spikevax is available to children aged 6 months to 11 years only if they are at higher risk. The WHO advises an eight-week interval between primary series doses, and additional booster doses are approved in some regions to maintain immunity.
Key Updates on Efficacy and Protection
Recent data highlights mRNA-1273’s effectiveness against SARS-CoV-2 variants, including Omicron sub-variants. While two doses of the vaccine showed an effectiveness of about 30.4% against Omicron infection, a third dose increased this protection to approximately 62.5%. The vaccine offers sustained strong protection against severe disease, hospitalization, and death, even as its effectiveness against symptomatic illness may be more modest.
Real-world studies consistently show mRNA-1273 provides robust protection. For example, a study indicated a third dose of mRNA-1273 lowered the risk of COVID-19 hospitalization by 32% after 90 days compared to another mRNA vaccine in immunocompromised adults. This protective effect against hospitalization persisted, showing reductions of 29% at 180 days and 23% at 270 days. Boosting significantly reduces the incidence of Omicron BA.1 infections.
Ongoing Safety Monitoring and Findings
Continuous post-market surveillance and large-scale safety studies provide insights into mRNA-1273’s safety profile. Systems like the Vaccine Adverse Event Reporting System (VAERS), co-managed by the CDC and FDA, collect reports of adverse events. From January 2021 to October 2022, VAERS received over 398,556 reports related to mRNA-1273.
Common adverse events for mRNA-1273 include headache, fatigue, fever, dizziness, nausea, injection site pain, chills, and pain in the extremities. While serious adverse events remain rare, monitoring has identified a risk of myocarditis, an inflammation of the heart muscle, particularly in young males aged 18-35 after the second dose. These cases are typically mild, respond well to treatment, and are less severe than myocarditis caused by COVID-19 infection. Anaphylaxis, a severe allergic reaction, has also been reported at a rate comparable to other licensed vaccines, primarily in individuals with a history of severe allergies.
Future Outlook and Development
mRNA-1273’s future involves continued development to address evolving public health needs. Moderna expects updated Spikevax vaccines for the 2025-2026 respiratory virus season for eligible U.S. populations. These updated formulations, based on JN.1 lineage strains, aim to provide targeted protection against circulating variants.
Beyond Spikevax, Moderna’s next-generation mRNA COVID vaccine, mNexspike (mRNA-1283), received FDA approval in May 2025 for adults 65 and older, and for individuals aged 12 to 64 with specific risk factors for severe disease. This new vaccine targets a specific portion of the SARS-CoV-2 spike protein, allowing for a smaller dose. Research is also exploring the vaccine’s use in various populations, including younger children and immunocompromised individuals, with clinical trials like KidCOVE showing promising safety and immune responses in children aged 6 months to 5 years.