Undesirable effects after vaccination

Vaccines are very safe products, but like drugs, they are medicinal products and, like all drugs, they can have some side effects. This side effect may be an adverse, undesirable sign, abnormal laboratory finding or symptom. In order to increase the rates of vaccination, the acceptability of vaccines by the society and the quality of service; ASIE surveillance is an essential part of the immunization program. In this way, undesirable effects are monitored regularly, whether they are due to the vaccine or not, and measures can be developed against application errors.



Undesirable effects that develop after vaccination can manifest themselves in many different ways and are grouped into five groups:

• Vaccine-Related Reaction : (depending on vaccine content): It is a finding that develops or exacerbates due to one or more substances in the vaccine content. Generally, there are mild side effects such as redness, swelling, pain, fever, vomiting, weakness and do not need to be reported. Example: Edema of the limbs following DTP vaccination.
• Vaccine Production Quality-Related Reaction : It is a finding caused or exacerbated by quality elements during the production phase of the vaccine. Example: The development of a paralytic polio picture due to inactivation of the inactivated polio vaccine from the production stage.
• Reaction Related to Vaccine Administration: These are the findings due to improper transport, distribution, prescription or administration of the vaccine. These are more common but preventable errors that are due to practitioner error, such as incorrect vaccination, incorrect site application, incorrect diluent use, overdose, improper storage or handling. Example: Transmission of infection during multiple dose vaccine administrations.
• Reaction Caused by Fear of Vaccine: Fainting, dizziness, tinnitus, trembling in hands due to fear of injection. Example: Development of vasovagal syncope during or after vaccination.
• Random Reaction: Events that occur during or after vaccination but are not related to vaccine content, production quality, administration, or fear of vaccines. Example: Fever development due to another disease in the same period as the vaccine, which cannot be associated with the vaccine.

Post-vaccine serious event and post-vaccine severe adverse event may differ. The severity of the undesirable finding after vaccination (eg, severe fever) and the severity of the event (eg, development of anaphylaxis after vaccination) are different. Serious adverse event after vaccination; It is a life-threatening condition that requires hospitalization or extension of the current hospital stay, results in permanent or significant disability, requires intervention to prevent permanent deterioration or damage, and can sometimes result in death.

The definition of vaccine reaction is mostly reactions that develop depending on the vaccine content or production quality. It is the undesirable response of the person who receives the vaccine despite the proper handling, distribution, preparation and administration of the vaccine. The vaccine reaction can manifest itself in two ways:

• Minor Reaction: Occurs within a few hours following vaccine administration. With appropriate intervention, it is resolved in a short time and does not pose a life-threatening hazard. Pain at the injection site may be local in the form of swelling, redness, or it may be systemic such as fever, widespread muscle pain, headache. It is a response of the host immune system to the vaccine antigen. Other additives in the vaccine may trigger this response.
• Severe Reaction: Rarely, undesirable effects such as anaphylaxis are life-threatening. It usually does not cause long-term damage. Seizures, thrombocytopenia, allergic reactions, hypotonic hyporesponsive attack, prolonged crying spells, mostly due to a substance in the vaccine.

Reactions due to vaccine applications vary according to the application error. It is necessary to take measures for these errors by analyzing the application time and place on the basis of the health facility. The first step in preventing reactions related to vaccine administration is the appropriate training of personnel who administer it.

Possible side effects due to vaccine administration error include:

• Non-sterile injection : Especially in multidose applications, reuse of needle or syringe, use of needle or syringe that has not been sterilized properly, or use of contaminated vaccine / diluent. There may be local abscess, swelling, cellulitis, sepsis, toxic shock syndrome, blood-borne disease (hepatitis B, HIV etc.) transmission at the injection site.
• Error in reconstitution: The vaccine is not adequately shaken, the wrong diluent is used, the vaccine or another drug is used instead of the diluent, and the reconstituted vaccine is reused after its expiration date. There may be local abscess, loss of effectiveness of the vaccine, the effectiveness of other drugs used such as insulin, oxytocin, muscle relaxants, toxic shock syndrome, etc.
• Vaccination in the wrong area: Intradermal application of the vaccine that should be administered intramuscularly, very superficial vaccine application, injection from the hip instead of the thigh area, etc. Local reactions such as abscess, swelling, redness, sciatic nerve damage may occur.
• Improper transportation and storage of the vaccine: Freezing of the vaccine during transportation, disruption of the cold chain as a result of exposure to extreme heat or cold, etc. Depending on the frozen vaccine, local reactions such as abscess, swelling, redness and loss of effectiveness of the vaccine may occur.
• Vaccination to contraindicated people: It is caused by the health personnel not paying attention to the contraindications of the vaccine. Severe, preventable reaction may develop.

Reactions due to fear of vaccines are not related to vaccine content or production quality. They develop due to the person’s fear of injections. These are usually:

• Fainting
• Vomiting
• Excessive breathing
• Convulsion

Vaccination campaigns should be considered as an opportunity to vaccinate large numbers of people in a short time and to monitor side effects. During the campaigns, the Post Vaccine Adverse Effects monitoring system of the country / region or health facility can be reviewed, the possibility of error of the health personnel working in a busy schedule can be followed, the practitioners can be gained experience, and the people who have been vaccinated can be informed collectively about the undesirable events.



Minimizing vaccine side effects is possible by complying with the standards set for vaccine administration, storage, transportation and production, and paying attention to contraindications.

Management of Post Vaccine Adverse Effects

• Redness, swelling, etc. at the injection site. application of cold compress to the injection site, use of antipyretic
• For prolonged bleeding Pressing the injection site in short-term bleeding, applying pressure with a thick gauze cloth in prolonged bleeding and keeping the injection site above the heart level
• Sitting or laying the person to be vaccinated for fear before vaccination
• For sweating in the hands and feet, coldness, nausea, drowsiness, dizziness, poor vision Laying the person down, loosening tight clothing and keeping the airway open, applying cold to the face and neck area, keeping under observation.
• Intervention for loss of consciousness if there is a fall and related injury, if it takes a long time, appropriate emergency intervention
• Requires appropriate emergency response for anaphylaxis (epinephrine, oxygen, fluid supplementation, etc.).

Undesirable effects after vaccination is one of the most common hesitations of parents, especially in childhood vaccination applications. One of the most effective methods against vaccination hesitations is to inform families appropriately and adequately about the undesirable effects after vaccination.

While evaluating the side effects of the vaccines, it is necessary to examine the effects and side effects of the diseases prevented by the vaccines. In this way, it can be better evaluated whether the vaccines are postponed due to their rare side effects or the fight against the serious and frequent side effects of diseases that may develop due to non-vaccination is important for children’s health.