Vaccines protect against infections, but they might also cause side effects, called “adverse events”. Most of these symptoms are transient and resolve by themselves and are natural effects of the immune response provoked by immunization (vaccination).
Side effects may occur as:
- pain, redness or swelling at the site of administration;
- fatigue, weakness, light-headedness;
- headache, nausea;
- subfebrility or fever.
Their purpose is not to treat a disease or “repair” the deranged functions of the body, but to “teach” and strengthen the immune system to fight against a specific pathogen. Nevertheless, the occurrence of these symptoms does not necessary indicate the causative effect of the vaccine, they might as well be a coincidence or the result of the so-called nocebo effect (by expecting side effects, the vaccinated person shows psychosomatic symptoms). Vaccines belong to the group of immunobiological products, a special group of medicines.
The term “side effect” is usually used regarding medications, while healthcare professionals prefer to use the term “adverse events of vaccination” by describing the same phenomenon. Vaccination has risks (as well as hiking does) and might result in complications, such as muscle ache after hiking. Still, we do not want to deter anyone from hiking because of muscle soreness, nor from getting vaccinated, obviously. Vaccination is a kind of “physical exercise”, exercise of the immune system, and the “muscle fever” that occurs after vaccination had been called “side effects” for a long time – today we rather call them “adverse events of vaccination” (vaccine reaction).
“Adverse events of vaccination” is a wider expression, than side effects. Side effects (or vaccine reaction) occur after the proper administration (complying with its official instruction manual) of the vaccination and that is listed in the instruction manual. On the other hand, every symptom falls within the “adverse events of vaccination” category that occurs after vaccination and of which connection with the event of vaccination cannot be excluded.
Adverse events can be categorized based on their occurrence:
- very common (occur in more than 1 of 10 vaccinated individuals);
- common (occur in more than 1, but less than 10 cases of 100 vaccinated individuals);
- uncommon (occur in more than 1, but less than 10 cases of 1000 vaccinated individuals);
- rare (occur in more than 1, but less than 10 of 10 000 vaccinated individuals);
- very rare (occur only in case of more than 10 000 vaccinated individuals).
You can get more information on the adverse events and of their frequency of a specific vaccine in the product’s patient information leaflet.
However, it is important to note that the vaccination-related risks (in most cases) are incomparably, an order of magnitude lower than the complications of the vaccine-preventable diseases.
Vaccine surveillance
It can be stated without any doubt that vaccines might provoke (in rare or very rare cases) conditions with severe symptoms (e.g. anaphylactic reaction). Moreover, severe conditions might develop after vaccination, regardless of that. The vaccines’ instruction manual and the patient information leaflet contain all the known adverse events of the vaccines, even those that have been registered at least once after hundreds of thousands of vaccinations.
All adverse events must be reported and investigated. Regarding vaccines, the rule of “presumption of innocence” does not apply: their efficacy, safety and innocuity must be continuously verified. The investigation of adverse events falls within the scope of health care authorities, and it is always implemented by a committee. Their purpose is to distinguish the real consequences of the vaccines from coincidental conditions.
Vaccine Adverse Event Reporting System
Adverse events of vaccinations must be reported in both adult and children’s cases. Adverse events – including vaccination reactions (side effects) and vaccination accidents- the doctor in charge of vaccination and the perceiver (doctor, patient or relative) reports to the regional epidemiological and public health department and to the National Institute of Pharmacy and Nutrition (in Hungarian: Országos Gyógyszerészeti és Élelmezés-egészségügyi Intézet, OGYÉI) simultaneously. OGYÉI operates an online reporting system accessible to everyone.
The protocol of the reporting process of adverse events of vaccinations and the reporting form are accessible and can be downloaded at the http://www.oltasbiztonsag.hu website.
The reporting form must be sent to the regional epidemiological and public health department by mail or in electronical form.
