EMA Draft Guideline: Quality Aspects of mRNA Vaccines

The European Medicines Agency (EMA) has released a draft guideline outlining "Quality standards for mRNA Vaccines", focusing on manufacturing, characterization, and regulatory requirements. With mRNA technology emerging as a pivotal platform in vaccine development, particularly during the COVID-19 pandemic, this guidance aims to ensure that all mRNA vaccines meet consistent quality, safety, and efficacy standards across the EU.

The guideline applies to:

mRNA vaccines for infectious diseases (e.g., COVID-19, influenza).
Products with synthetic, non-replicating mRNA, delivered typically using lipid nanoparticles (LNPs).
Single or multi-component vaccines, where each mRNA may encode one or more antigens.

It excludes self-amplifying mRNA, mRNA used for gene therapy, or mRNA expressing monoclonal antibodies.

Manufacture

Starting Materials:
- Linear DNA template: Must be fully sequenced, with details on its origin (e.g., cell-based or enzymatic synthesis).
- Nucleotides and capping reagents: These require supplier certifications and purity testing.
- Critical testing for DNA templates: Identity, sequence integrity, residual host cell DNA/RNA, and endotoxins.
Process Controls:
- Enzymatic synthesis (via in vitro transcription) must minimize impurities like double-stranded RNA (dsRNA) or truncated mRNA.
- Residual DNA templates must be quantified and characterized for fragment size.

Characterization

Primary structure: Confirm sequence integrity of coding/non-coding regions using:
- Reverse transcription/sequencing.
- High-throughput sequencing (NGS).
- Capillary electrophoresis.
Higher-order structure: Assessed via circular dichroism (CD) or differential scanning calorimetry (DSC).
Functionality: Verify translation into correct protein using in vitro assays (e.g., Western Blot).

Impurities

Product-related:
- Incomplete mRNA, dsRNA, cap/poly-A tail variants, frameshift mutations.
- Controlled via specifications (e.g., dsRNA ≤ 1%).
Process-related:
- Residual DNA, enzymes, host cell proteins, unincorporated nucleotides.

Stability

Stability studies must justify storage conditions and shelf life.

Finished Product

Composition

Includes mRNA active substance, lipid nanoparticles (LNPs), and excipients (e.g., sugars, buffers).

Pharmaceutical Development

Optimize LNP formulation for mRNA protection, cellular uptake, and immunogenicity.
Demonstrate compatibility between mRNA and delivery system.

Control of Excipients

LNPs require characterization of lipid ratios, particle size, and polydispersity.

Finished Product Testing

Identity: mRNA sequence confirmation.
Potency: Cell-based assays measuring antigen expression.
Purity: Residual DNA (< 10 ng/dose), host cell proteins, and process residuals.
Safety: Endotoxins (< 5 IU/dose), sterility.

Regulatory Considerations

Strain Changes

For vaccines targeting evolving pathogens (e.g., influenza):
- Comparative analytical studies required for new strains.
- Clinical data may be waived if platform technology is validated.

Multivalent Vaccines

Bivalent/multivalent formulations must demonstrate no interference between mRNA components.

Self-Amplifying mRNA (saRNA)

Additional controls are needed for replicase activity and unintended protein expression.

Platform Technologies

If justified, prior knowledge (e.g., from COVID-19 vaccines) can streamline development for new targets.

Stakeholders can submit feedback via the EUSurvey portal until 30 September 2025. This guideline marks a critical step in harmonizing mRNA vaccine standards across the EU, balancing innovation with patient safety.