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Vaccines are medicinal products which, when introduced into the body, trigger a response of the immune system against specific pathogens, which may be: viruses, bacteria. Their use is particularly important in the prevention of viral diseases, because there are almost no effective drugs for them.
Classic vaccines:
Vaccines can be specific – reducing the risk of developing a particular disease, and non-specific – aimed at increasing the overall resistance of the body.
Specific vaccines, the so-called traditional (classic), may include:
- live pathogens (the only vaccine of this type was against smallpox),
- weakened (attenuated) live microorganisms, e.g. against measles, mumps, rubella and varicella or
- killed (inactivated), e.g. pertussis whole cell vaccine
- decongestant (toxoid) toxins, e.g. tetanus vaccine, diphtheria.
Newer generation vaccines contain only fragments of microorganisms, e.g. acellular pertussis vaccine, subunit one of the influenza vaccines (subunit), split virus fragments, e.g. other influenza vaccine (split). Some of the above types of vaccines can be conjugated – fragments of microorganisms are bound in them with a specific protein. They include, among others vaccines against pneumococcal, meningococcal and Haemophilus influenzae type B infections.
Vaccines can be:
- single (monovalent), i.e. protect against only one disease
- combined (polyvalent) – immunizing simultaneously against several diseases, eg six-component vaccine against diphtheria, tetanus, pertussis, polio, Hib and hepatitis B. Such vaccines are more effective, and also significantly reduce the number of punctures.
Latest generation vaccines
It is not always possible to reduce the risk of contracting an infectious disease using the so-called vaccine. traditional, incl. due to individual intolerance and the possibility of allergic reactions. In such cases, vaccines based on recombinant antigens, produced by genetic engineering, are used. This is a very difficult process because the appropriate vaccine antigen is often selected from several thousand proteins of the pathogenic microorganism, then it is incorporated into genetically modified cells (e.g. yeast), where they begin to produce a protein that may be a vaccine antigen. Such a vaccine is e.g. hepatitis B and HPV vaccines.
The latest are genetic vaccines that have not been used in humans so far. After being administered to the human or animal organism, the DNA they contain enters the cells where it is read and – very generally speaking – forces the production of immune-inducing proteins. Two such vaccines are known and used: against West Nile virus for horses and against certain salmon disease virus.
More and more advanced are research, also in Poland, on appropriately modified plants that can be vaccines, e.g. lettuce protecting against hepatitis B.
In some cases, the so-called passive immunization, consisting in the rapid induction of short-term immunity with the use of an appropriate immunoglobulin. They are usually used after contact with an infectious agent, when there is no time to induce immunity through traditional vaccination.
Post-vaccination reactions
Vaccines, like all medicines, can cause side effects. These are usually: redness, swelling, pain at the injection site, rarely – increased temperature, malaise, headache. These symptoms are often – wrongly – explained as “falling ill after vaccination”. Meanwhile, they may be the result of a specific reaction of the vaccinated person’s body, but also an injection error, e.g. instead of intramuscularly or subcutaneously into a blood vessel. Such symptoms may occur sporadically even after several weeks, and then the vaccine is also accused of contributing to the disease – only that it is not known for what.
Each type of vaccine, both traditional and new generation, has its advantages and disadvantages, because no one has managed to develop an ideal vaccine – 100% effective. and causing no side effects or complications.
Prevention of infectious diseases through mass vaccination is one of the greatest achievements of medicine. Even if side effects occur after vaccination, it should be remembered that complications from infectious diseases are much more common and can even kill.
So to vaccinate or not to vaccinate? VACCINE!
Vaccinations are only effective when carried out on a mass scale. If a small percentage of the population is vaccinated, or there are gaps between vaccinations not justified by vaccination dosing, pathogenic microorganisms may reactivate or mutate, resulting in the emergence of new pathogenic strains against which the available vaccines are not effective.
Substantive consultation: Paweł Grzesiowski, MD, PhD, head of the Department of Prevention of Infections and Hospital Infections at the National Medicines Institute in Warsaw.
Material prepared for the workshops in the series “Quo vadis medicina?” entitled: “Vaccinations as a pass to health”, organized by the Association “Journalists for Health”, March 2010