Normal post-vaccination reactions
They are not a contraindication to continuing the vaccination schedule if their severity does not exceed the permissible norms specified in the product instructions. These include:
- Local reactions: hyperthermia and edema at the injection site. The BCG vaccine is characterized by the formation of a specific papule, which normally is accompanied by local tissue necrosis.
- Systemic reactions: transient fever, general malaise, and decreased appetite.
- Specific manifestations: the administration of dry attenuated vaccines (e.g., mumps, measles, or rubella) may cause a transient rash.
Such conditions resolve independently. Specific therapy is not required, except for symptomatic care (e.g., taking antipyretics for pronounced fever).
Causes and types of side effects
Side effects are generally divided into common (malaise, moderate temperature rise, local changes) and rare (sleep disturbances, joint pain, headache, vomiting, syncope).
The etiology of these conditions is associated with two main factors:
- The presence of impurities in vaccine preparations (e.g., preservatives, stabilizers, or traces of antibiotics).
- The action of pro-inflammatory factors that cannot be separated from the active antigen. A prime example is the high reactogenicity of the DTaP vaccine, which is entirely due to its pertussis component.
Severe post-vaccination complications
These are rare but serious conditions requiring emergency measures. Globally, they are divided into three groups: toxic, allergic, and nervous system disorders. A separate category is the post-vaccination infectious process triggered by live attenuated pathogens.
General criteria for severe complications:
- Anaphylactic shock and severe generalized allergic reactions.
- Convulsive syndrome.
- Body temperature elevation above 40 °C.
Specific complications:
- Upon DTaP administration: atypical prolonged piercing cry and pronounced neurological symptoms (convulsions, gaze fixation, head nodding). The frequency of such encephalitic reactions is extremely low: 1 case per million doses.
- Upon OPV administration: there is a rare risk of developing vaccine-associated paralytic poliomyelitis (VAPP).
Upon detecting a severe complication, the physician is obliged to immediately hospitalize the child and issue an emergency notification to the Center for State Sanitary and Epidemiological Surveillance (Sanitary Epidemiological Surveillance Center).
Contraindications and global significance
Despite the proven safety of modern preparations, strict contraindications to vaccination exist:
- Immunodeficiency states.
- Severe reactions or complications following a previous administration of a similar vaccine.
- Allergy to any components of the preparation (e.g., to the Al(OH)2 adjuvant in liquid hepatitis B vaccine, the preservative thimerosal, or traces of antibiotics in dry viral vaccines).
It is important to understand that isolated cases of complications (including fatalities) are absolutely incomparable to the global positive effect of immunization. Vaccination has allowed humanity to eradicate deadly epidemics and has radically reduced mortality rates from infectious diseases, especially in childhood.
For quick memorization of absolute contraindications to vaccination, use the mnemonic IAO: Immunodeficiency, Allergy to components, Organism complications from the previous dose.
Class and exam questions
Why are antiviral vaccines administered only 12–15 months after birth?
Such a delay is necessary to prevent the neutralization of the vaccine preparation by maternal antibodies circulating in the child's blood serum during the first year of life.
Is local tissue necrosis after the BCG vaccine considered a complication?
No, the formation of a specific papule with local necrosis is a normal (acceptable) local post-vaccination reaction to this preparation.
What is the physician's tactic when a child exhibits a prolonged piercing cry following DTaP administration?
This is a sign of a severe neurological complication from the pertussis component. The physician must immediately hospitalize the patient and send an emergency notification to the Sanitary Epidemiological Surveillance Center.
What else to study on this topic
- Nature of antigens and vaccine composition (adjuvants, preservatives, stabilizers)
- Routine immunization schedules: primary and booster vaccination
- Mucosal vaccines: prospects for oral and nasal administration routes
- State system for recording and investigating adverse events following immunization (AEFI)
- Reporting forms and deadlines for submitting notifications for various types of complications
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