Assembly Line

How mRNA vaccines are made

An mRNA vaccine is built in a tube from a DNA template, not grown in eggs or cells.

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7
things upstream
23
raw sources
11
steps from the ground
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The short version

An mRNA vaccine is assembled in vitro. A DNA template carrying the code for one protein is copied by an enzyme into messenger RNA. The RNA is purified and then mixed with fats under controlled conditions so it wraps itself in tiny lipid nanoparticles. The product is filtered, filled into vials and kept cold.

  1. Make the DNA template

    A ring of plasmid DNA carrying the gene for the target protein is copied inside bacteria in a fermenter. The DNA is later purified and cut so it can serve as a pattern.

    Goes in
    WaterAir

  2. Copy it into RNA

    An enzyme called T7 RNA polymerase reads the template and builds a strand of messenger RNA from its building blocks. This is in vitro transcription, and it happens in a bioreactor, with no living cells involved.

  3. Remove the template

    Enzymes digest the leftover DNA. The RNA then goes through filtration and chromatography to strip out enzymes and fragments.

  4. Cap and tail the strand

    The RNA gets a protective cap on one end and a tail on the other so cells will read it and it will last long enough to work.

  5. Wrap it in fat

    A stream of RNA solution meets a stream of fats dissolved in ethanol inside a mixer. The fats fall out of solution and close around the RNA, forming lipid nanoparticles.

    Goes in
    EthanolWater

  6. Purify and concentrate

    Cross-flow filtration swaps the liquid for a buffer and removes the alcohol. The nanoparticle suspension is checked for size and RNA content.

  7. Fill and freeze

    Sterile lines fill glass vials, which are stoppered, inspected and stored cold. Some mRNA vaccines require ultracold freezers.

    Goes in
    Glass bottle
End of the linemRNA vaccine

Worth repeating

  • Lab-made mRNA injected into mouse muscle produced the encoded protein in living tissue, which led to the idea of mRNA vaccines.
  • Some mRNA vaccines need ultracold storage before distribution, while others do not.

Back to the ground

Follow every input upstream and mrna vaccine starts as these 11 raw sources.

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Sources

Cite this page: "How mRNA vaccines are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/vaccine

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