Vaccine

Whole-cell: for example hepatitis A and influenza vaccines.

Toxoid: produced using detoxification of the toxin that causes the disease. These include the tetanus and diphtheria vaccines.

Subunit: only contain fragments of viruses, such as the flu vaccine.

Recombinant: made using the production of the antigen in non-human cells such as yeast, hepatitis B and papilloma cells.

Conjugate vaccines: such as pneumococcal, meningococcal, Haemophilus type B.

Vector vaccines: These vaccines use non-pathogenic viruses to present the genetic code of the micro-organism’s antigens to the recipient's cells so that they produce protein antigens that will stimulate the immune response. Vector vaccines are quick to produce and are also cheaper than nucleic acid vaccines. The carrier virus can have replicative capacity (Ebola vaccine) or non-replicative capacity (COVID-19 vaccine).

Nucleic acid vaccines (mRNA): the RNA strand carrying the virus antigen information is surrounded by a lipid nanoparticle that facilitates entry and gives it stability. Once inside the cell, this RNA transfers the information so that the cell's machinery can transcribe it and proceed to make the antigen that will stimulate the immune response. The RNA strand degrades and never integrates into the cell. COVID-19 is one example, but there will be more in the future.

DNA vaccines: are more stable and do not need to be protected by a lipid capsule. The DNA strand needs to be introduced into the cells. The technique used is called electroporation. It uses low-level electronic waves to allow the DNA to enter the cells and, once inside, the strand passes the information to its own messenger RNA and begins to produce the antigen. There are currently no DNA vaccines available on the market.