Post-vaccination complications

Normal vaccination process and potential complications

The administration of any vaccine initiates the formation of artificial active immunity: the body recognizes the antigen and independently synthesizes protective antibodies. Since it is impossible to select an individual dose for every person, the drugs are designed to provide an adequate response in the vast majority of people in the population.

The line between a normal course and pathology is conveniently illustrated by immunization against tuberculosis (BCG vaccine), which protects against generalized and disseminated forms of infection.

Normal reaction following intradermal BCG administration proceeds in stages:

• After 4–6 weeks, a papule up to 8 mm in size appears at the injection site.
• Moderate local inflammation develops, with a small area of necrosis and crust formation permitted.
• After 2–4 months, the process concludes completely with the formation of a neat post-vaccination scar (up to 5 mm).

Post-vaccination complications in this context are extremely rare. They include:

• Regional lymphadenitis;
• Cold abscess;
• Periostitis;
• Formation of a pathological keloid scar.

Admission algorithm and prevention of adverse events

To avoid complications, the decision to perform immunization is made exclusively by a physician after a thorough examination of the patient.

1. Status assessment: Thermometry is mandatory. If body temperature exceeds 37 °C, the procedure is postponed.
2. Legal aspect: Informed voluntary consent must be signed by the patient themselves or their legal representative.
3. Documentation: Every administration is strictly recorded in medical record accounting forms and the vaccination certificate. The physician must indicate the date, drug name, dose, batch number and control number, expiration date, and the nature of the reaction to the injection.

Drug compatibility rules

The modern schedule covers protection against 12 major infections, which often requires administering multiple drugs on the same day.

• Simultaneous administration of vaccines against different diseases is permitted, but must be done with different syringes and at different injection sites.
• Inactivated influenza vaccine can be safely combined with any other inactivated drugs.
• Strict exception: it is strictly prohibited to simultaneously administer vaccines against tuberculosis and yellow fever.

Vaccination of special patient groups

Patients with chronic and immunodeficient conditions require modification of standard regimens to reduce the risk of complications and achieve the required protective antibody titer.

• Immunosuppressive therapy: The vaccination course must be completed well in advance (4–6 weeks before a cladribine course and at least 6 weeks before divozilimab administration). Live vaccines are not recommended during such treatment until the corresponding cell pool recovers.
• Oncology and HIV: Patients who have completed immunosuppressive treatment are permitted to receive vector vaccines (e.g., against COVID-19) without additional restrictions. HIV-infected children must be administered drugs against diphtheria, tetanus, pertussis, hepatitis B, and Haemophilus influenzae, and also vaccinated against influenza annually.
• Chronic diseases: Patients with Crohn's disease retain the risk of an inadequate response, therefore a check of immunity levels (e.g., quantitative anti-HBs testing) is recommended one month after the course. Children with spinal muscular atrophy (SMA 5q) receive the pneumococcal vaccine according to a special schedule: three doses before one year of age, and the fourth after 12 months.

Class and exam questions

What else to study on this topic

• Structure and logic of the National Schedule of Preventive Vaccinations (NSPV)
• Emergency post-exposure prophylaxis of infectious diseases
• Features of the development of artificial active and passive immunity
• Chemoprophylaxis of tuberculosis in exposed contacts
• Specifics of immunization in patients with autoimmune diseases and SMA

Other topics in the "Additional Topics" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.