A vaccine is a preparation thanks to which we are able to obtain immunity to many diseases - we all know that. But how do vaccines work? How do vaccines trigger the body's immune response to make them effective and safe? What diseases do vaccines protect against and what are their types?

Vaccinesare considered to be one of the greatest successes of medicine. Thanks to vaccines and vaccinations, it is possible to prevent many serious diseases - ones that caused epidemics in the past and decimated humanity. Vaccinations allowed, among others to completely eliminate smallpox and polio virus types 2 and 3, as well as to significantly reduce the incidence and mortality due to diseases such as whooping cough, tetanus, measles and tuberculosis.

The link between immunity and the development of infectious diseases was noticed as early as the Middle Ages, when it was discovered that people who contracted an infectious disease usually do not get sick with it again. This observation prompted the doctors of the time to try with preparations that were intended to protect against infection.

Historical sources report about attempts to create vaccines, incl. from powdered smallpox scabs or secretions taken from people with mild disease - preparations based on them were then administered, with varying results, to people who had not yet suffered from the disease. The first real vaccine, however, was created much later, in the 18th century, and was developed by the British doctor Edward Jenner.

His experiment, consisting in inoculating an eight-year-old boy with cowpox virus, turned out to be successful - the boy became immune to smallpox, one of the greatest plagues of humanity.

Vaccine - what is it? How do vaccines work?

Vaccineis a preparation whose task is to induce an immune response similar to the one that the body obtains in a natural way, i.e. during contact with bacteria or viruses. This allows you to obtain immunity similar to that after illness or infection - but without getting sick.

Vaccines are given to protect the body against the severe course of the disease and its complications. Even if a vaccinated persongets sick, the course of the infection is much milder than it would have been without vaccination.

Types of vaccines

A vaccine contains one or more antigens - that is why some vaccines, the so-called monovalent vaccines protect against only one disease (e.g. tuberculosis vaccine) and others, the so-called polyvalent vaccines protect against various infections (e.g. DTP vaccine against diphtheria, tetanus and pertussis).

These antigens are obtained from live or killed (inactivated) pathogens, their fragments (which have previously been specially purified) or metabolic products, antigens for vaccines are also produced by genetic engineering.

Due to the antigen used, vaccines are divided into:

  • live attenuated vaccine (weaned ) contains microorganisms that are able to multiply and under normal conditions could lead to the development of infection, but thanks to modifications they have been deprived of pathogenic properties. Live vaccines include, for example, tuberculosis vaccine. Live vaccines are given in one dose because they trigger a strong immune response in the body.
  • inactivated vaccine, i.e. killed vaccine , contains inactivated microorganisms - that is, inactivated (e.g. by radiation or high temperature. Such vaccines include, for example, tick-borne encephalitis vaccine. Inactivated vaccines are administered in several doses - with each subsequent dose) the level of antibodies increases and the body's resistance to this particular pathogen or pathogens Inactivated vaccines include toxins, containing toxins with antigenic properties, but devoid of virulence (such anatoxin is, for example, the tetanus T component and D diphtheria present in the DTP vaccine.
  • subunit vaccine- contains fragments of microorganisms combined with carriers, e.g. protein carriers.
  • recombinant vaccine- a vaccine in which there are either antigens or substances that are to stimulate their production, obtained by genetic engineering, e.g. by incorporating the genetic material of the virus or bacteria into yeast or mammalian cells. In the group of these vaccines there are well known vaccines against hepatitis B. Recombinant vaccines also include vector vaccines in which the mRNA of a pathogen is introduced into another, modified virus. After administration of such a vaccine, proteins of the pathogen against which immunity is to be produced are produced (for example, this is how a vaccine worksAstraZeneca against COVID-19). Recombinant vaccines are also mRNA vaccines (e.g. the Pfizer-BioNTech vaccine against COVID-19).

There are also other substances in vaccines, such as adjuvants (to strengthen the body's immune response), preservatives and stabilizers.

What diseases do vaccines protect against?

The vaccines developed so far protect against many diseases - some of them protect against the occurrence of several different diseases, e.g. pneumococcal vaccine protects against sepsis, pneumonia, otitis and meningitis.

Diseases that can be protected against thanks to vaccines include :

  • flu
  • COVID-19
  • diphtheria
  • whooping cough
  • tetanus
  • tuberculosis
  • diseases caused by Haemophilus influenzae type b (Hib) - e.g. meningitis, epiglottitis, sepsis, pneumonia, phlegmon of the subcutaneous tissue
  • tick-borne encephalitis
  • invasive meningococcal disease
  • measles
  • chickenpox
  • rotavirus diarrhea
  • rubella
  • piggy
  • hepatitis B
  • rabies
  • damn
  • yellow fever
  • hemorrhagic fever.

Currently, the existing vaccines are constantly being improved, and work on new vaccines, e.g. against HIV or malaria, is still ongoing. Researchers are also working on vaccines against cancer as well as allergy vaccines.

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