The COVID-19 mRNA vaccine consists of messenger ribonucleic acid (mRNA) that carry instructions to make the spike protein of the virus. The mRNA used in the vaccine is synthesised and not extracted from actual viruses.

After being given by intramuscular injection, the vaccine mRNA is taken up by cells which then produce the spike protein. This stimulates the production of a good antibody and cellular immune response to the spike protein that protects the vaccinated person because the spike protein is an important part of the SARS CoV-2 virus.

The spike proteins are however incapable of forming SARS CoV-2 viruses or causing COVID-19 infection. The vaccine mRNA only persists for two days before it is naturally broken down by the body. It does not enter the nucleus of cells and hence cannot interfere with the DNA of the vaccine recipient.