Products
mRNA vaccines are commercially available as injectables. The first in this group to be approved in many countries was BNT162b2 from BioNTech and Pfizer on December 19, 2020. Moderna’s mRNA-1273 is also an mRNA vaccine. It was released in the EU on January 6, 2021. Both are covid-19 vaccines.
Structure and properties
mRNA (short for messenger RNA) is a ribonucleic acid (RNA) that is single-stranded, unlike DNA. They are polymers of ribonucleotides. The monomers consist of a carbohydrate (sugar, ribose), a phosphate, and one of the following nucleic bases:
- Adenine (A)
- Guanine (G)
- Cytosine (C)
- Uracil (U)
Effects
Unlike classical vaccines, mRNA vaccines do not contain proteins of the pathogens, but nucleic acids that code for the antigens. They are produced by the body itself in the cells after administration. The mRNA contains the information for the amino acid sequence of the antigens. It can be identical to the natural sequence or modified. In the cell, the mRNA is translated to the proteins at the ribosomes in the endoplasmic reticulum. The antigen formed in this process is recognized by the immune system and triggers an immune response that ultimately leads to the formation of antibodies directed against the pathogen. When the organism comes into contact with the pathogen, it is protected by the antibodies and the immune system. mRNA is incorporated into larger particles for delivery, for example nanoparticles and liposomes. These can accommodate multiple mRNA molecules simultaneously. mRNA is not infectious, so it cannot cause infectious diseases. It can be developed and produced more quickly than classical vaccines. The processes are simpler and can be better standardized. In addition, mRNA is not integrated into the human genome and is degraded in the body by naturally occurring ribonucleases.
Areas of application
mRNA vaccines are being developed primarily for the prevention of bacterial and viral infectious diseases. They are also being investigated for the treatment of cancer and for the elimination of antigens.
Dosage
mRNA vaccines are usually administered parenterally, for example, as an intramuscular injection. Other modes of administration are being investigated.
Adverse effects
Adequate information is not yet available regarding potential adverse effects. In clinical trials with mRNA vaccines, local reactions at the site of administration such as redness, swelling, and pain have been reported, as have systemic complaints such as joint pain, fatigue, fever, headache, and muscle pain. Allergic reactions and an exuberant immune response should also be expected.
