Why are Spikevax (Moderna COVID-19 vaccine) and Mnexspike available?

Availability of Spikevax and mRNA COVID-19 Vaccines

Spikevax (Moderna COVID-19 vaccine) is available because it received full FDA approval after demonstrating high efficacy against severe COVID-19 disease (98.2%) and has a well-established safety profile, making it a recommended vaccine by major health authorities worldwide. 1

Vaccine Development and Authorization

Spikevax (mRNA-1273) was initially granted Emergency Use Authorization (EUA) by the FDA in December 2020, with ACIP issuing interim recommendations for its use among people aged ≥18 years. After extensive safety monitoring and efficacy data collection, the FDA approved the Biologics License Application (BLA) for Spikevax on January 31,2022, transitioning it from emergency authorization to full approval status. 2

The development timeline included:

• December 2020: Initial EUA granted 3
• January 2022: Full FDA approval as Spikevax 2

Efficacy and Safety Profile

Spikevax has demonstrated:

• 94.1% efficacy against symptomatic COVID-19 disease
• 98.2% efficacy against severe disease (95% CI 92.8% to 99.6%) 1
• Similar safety profile to other mRNA vaccines with primarily transient reactogenicity

Safety monitoring for COVID-19 vaccines has been the most comprehensive in U.S. history, utilizing:

• Vaccine Adverse Event Reporting System (VAERS)
• V-safe active surveillance system 4

Technological Advantages

mRNA vaccines like Spikevax represent a revolutionary approach in vaccine technology with several advantages:

• No live virus components (cannot cause infection)
• Rapid degradation after protein production (no permanent genetic material)
• Less temperature-sensitive than some other mRNA vaccines, making it easier to transport and store 1

Variant Adaptation

One key reason for continued availability of Spikevax and other mRNA vaccines is their adaptability to emerging variants:

• The mRNA platform allows for relatively quick modifications to address new variants
• Variant-adapted versions have been developed to improve protection against Omicron and other variants 5
• Both monovalent (single strain) and bivalent (two strains) versions have been produced to address evolving virus mutations

Administration Protocol

For adults aged ≥18 years:

• Primary series: 2 doses (100 μg/0.5 mL each) administered 4 weeks apart
• Booster doses available with updated strain compositions to address variants 1, 2

Special Populations

Spikevax is particularly valuable for:

• Immunocompromised patients
• Those with autoimmune conditions
• High-risk populations

This is because mRNA vaccines do not contain live virus and have demonstrated strong safety profiles in these groups. 1

Practical Considerations

The continued availability of Spikevax and other mRNA COVID-19 vaccines reflects:

• Strong efficacy data against severe disease and hospitalization
• Favorable safety profile with primarily mild, transient side effects
• Adaptability to emerging variants
• Endorsement by major health authorities including CDC, ACIP, and the American College of Physicians 1

Common Pitfalls and Caveats

• Despite high efficacy, breakthrough infections can still occur, especially with new variants
• No vaccine provides 100% protection, emphasizing the importance of additional preventive measures when appropriate
• While generally safe, rare adverse events have been reported (e.g., anaphylaxis at 4.5 cases per million doses) 4
• Extended intervals between doses (8 weeks) may be optimal for some adults compared to the original 4-week interval 2