Classification and composition of vaccines


What is a vaccine? A vaccine is a preparation of biological origin containing antigens that stimulate our body’s immune system to produce acquired immunity, called post-vaccination immunization. The ability to stimulate the immune system is called immunogenicity.

Vaccines are used to obtain controlled immunity comparable to the natural immunization acquired after infection by a wild-type microorganism. European defines vaccines as “preparations containing antigens capable of inducing in humans the development of specific and active immunity against an infectious agent, toxin or antigen produced by them. this”.

What do vaccines contain?

Vaccines may contain: Microorganisms that have been chemically or physically inactivated (killed) without destroying their antigenic properties. Live microorganisms that have been deprived of their pathogenicity or treated to reduce their pathogenicity (attenuated) while retaining sufficient antigenic properties.

Purified antigens, obtained from micro-organisms by extraction, excreted by them or obtained by genetic engineering. How to store vaccines?

Vaccines should be stored in a place out of direct sunlight at 5±3OC (unless otherwise specified by the manufacturer). Vaccines should not be frozen, as they then lose their antigenic properties. Throughout the journey between the manufacturer and the vaccinated person, transport and storage must ensure that the correct temperature is maintained at all times, the so-called cold chain or “cold chain”.

How should the vaccine be labelled? What information must appear on the leaflet and the packaging? The vaccine package and package insert, as required by regulation, must contain the following information:

  • the name of the preparation
  • the number of the production batch or any other data allowing the identification of the  batch
  • recommended dose and route of administration
  • contraindications contraindications and precautions
  • storage conditions (e.g. temperature)
  • the shelf life (expiration date)
  • names and concentrations of preservatives used
  • the names of the excipients: antibiotics, adjuvants, aromatic substances (oral vaccines, generally sucrose) and stabilizers used in the composition of the vaccine
    a list of ingredients that may cause adverse effects

How are vaccines distributed?

Today’s vaccines can be divided into different categories based on their composition, origin and method of manufacture. Microbial antigens can be used in their natural form or rendered toxic by chemical (eg, by the action of formaldehyde) or physical (eg, by heating) methods. Enhanced immunogenicity, a measure of stimulation of the immune system by a vaccine, can be achieved by aggregation, polymerization or conjugation (combination) with a highly immunogenic carrier such as a protein.

Division of vaccines by route of administration

In terms of route of administration, vaccines are divided into two categories: injectable (intramuscular or subcutaneous) – most vaccines are given this way, oral – this is the usual route of administration for vaccines live, such as the attenuated rotavirus vaccine or the attenuated cholera vaccine. inhalation, which is given by spraying the vaccine into the nose. A live attenuated influenza vaccine (not available in Poland) is administered this way.

fusion proteins

Fusion proteins are non-toxic proteins made by combining several protein fragments, including a well-immunogenic carrier protein and an epitope (fragment of antigen) from a pathogenic microorganism. Fusion proteins are obtained by genetic engineering methods by combining a carrier protein gene (for example, the HbsAg antigen gene) with the gene coding for the epitope (antigen fragment) of the pathogenic microorganism .

The resulting fusion genes are then implanted into the microorganism which will produce the fusion protein (eg yeast cells). The fusion protein is then isolated and purified from the culture of such a genetically modified microorganism, which is used to produce an inactivated vaccine.

Anti-idiotypic antibodies

Anti-idiotypic antibodies are antibodies directed against the antibodies that one wishes to induce. They are like “mirror images” of the antigen binding site. Anti-idiotypic antibodies form in their antigen-binding site a structure analogous to the real antigen and can therefore be used for active immunization. Anti-idiotypic antibodies care a solution when the antigen in question is poorly tolerated and causes strong side effects.