Vaccines are biological medicines. However, the use of medicines is never 100% safe. Therefore, it is always necessary to consider the benefit and risk ratio.
The benefits of vaccines manifest in infectious diseases and complications (including deaths) that are prevented. In addition to reducing human suffering, the spread of infectious diseases affects our medical system in the broader sense as well. The smaller the amount of taxpayer's money spent on preventable diseases, the more it can be directed towards improving the quality of life, reducing queues or mitigating some other shortcomings.
The potential risk involves vaccine-related adverse reactions (hazardous and undesirable effects that occur when using normal doses of the medicine). Known side effects are described in the information leaflet of the package of the medicinal product. Patients should always read this leaflet prior to vaccination and, if necessary, consult with a doctor.
Side effects following vaccination may have been caused by:
- the vaccine;
- failure to comply with the requirements for the use of the vaccine;
- failure to comply with the requirements for conducting vaccination;
- unknown or unclear causes.
A random coincidence in terms of time is also possible, i.e. occurrence of illness close to the time of vaccination, but there is no causal relationship with vaccination.
The most common (occurs in about 1% of patients) vaccination side effects can be injection site pain, swelling, redness and general reactions such as fever, weakness, loss of appetite and headaches. Rare side effects may include extensive swelling at the injection site, transient low platelet count or acute allergic reactions. The likelihood of the latter is in the range of 1 in 1,000,000 vaccinated persons.
Vaccine-induced side effects are mostly mild and transient , and the benefits of the vaccination significantly outweigh the risks. Exceptions are situations where an increased likelihood of a severe side effect may be expected. In that case, vaccination is not conducted.
In developed societies, the spread of vaccine-preventable infectious diseases has decreased and is under control, and the risk of infectious diseases is almost non-existent. This is the result of well-functioning vaccination schedules. However, this situation only lasts as long as the number of vaccinated people remains high and diseases do not have the opportunity for spreading.
Studies that ensure safety
The safety and quality of vaccines (and all medicines) is guaranteed in two phases.
The first phase precedes the marketing authorization, i.e. widespread use of the vaccine. During this period, a multiphasic clinical study of the new medicine is conducted on people, in the course of which information on the effects, side effects, absorption, distribution, change, ejection, efficacy and safety of the medicine is collected. On the basis of this, presumptions about the effect of the medicine are compiled.
Extensive use of the medicine is made possible by a valid marketing authorisation. The marketing authorization for a new medicine is based on data from clinical trials conducted. In order to obtain a marketing authorisation, the applicant must demonstrate by scientific methods that the medicine is safe and effective for its intended use according to current level of modern medicine. In the European Union, a marketing authorisation can be applied centrally, i.e. a marketing authorisation is applied for from the European Medicines Agency, in which case the marketing authorization issued is valid in all EU countries.
You can also apply for a marketing authorisation from a single national medicines agency that assesses the efficacy, safety, and quality of the product against current requirements based on the application for marketing authorisation and the available materials. When issuing a marketing authorisation for medicines, the Estonian Agency of Medicines is advised by the Committee on Marketing Authorisations for Medicines, the members of which are appointed by the Minister of Social Affairs. In the case of a positive decision, the marketing authorisation shall be granted for five years. After five years, the marketing authorization is renewed indefinitely.
You can read more about pharmacovigilance (including vaccines) on the website of the Agency of Medicines.