Antigenic preparations for active immunization

Antigenic preparations for active immunization are designed to stimulate an immune response, helping the body develop immunity to a specific pathogen. These preparations include:

1. Live Attenuated Vaccines:

   • Weakened but live forms of the pathogen that replicate in the host without causing the disease.
   • Examples: Measles, Mumps, Rubella (MMR), Varicella (Chickenpox), Yellow Fever, Oral Polio Vaccine (OPV).

2. Inactivated (Killed) Vaccines:

   • Pathogens that are killed using heat or chemicals but can still trigger an immune response.
   • Examples: Inactivated Polio Vaccine (IPV), Hepatitis A, Rabies, Influenza (some types).

3. Subunit Vaccines:

   • Contain only the specific antigens (proteins or polysaccharides) of the pathogen that are necessary to trigger an immune response.
   • Examples: Hepatitis B, Human Papillomavirus (HPV), Pertussis (acellular pertussis in DTaP).

4. Toxoid Vaccines:

   • Inactivated toxins produced by bacteria. These toxins are modified to be harmless while still eliciting immunity.
   • Examples: Tetanus, Diphtheria.

5. Conjugate Vaccines:

   • Antigens (often polysaccharides) are chemically linked to a protein carrier to enhance immunogenicity, especially in infants and young children.
   • Examples: Haemophilus influenzae type B (Hib), Pneumococcal Conjugate Vaccine (PCV), Meningococcal Conjugate Vaccine.

6. Recombinant Vaccines:

   • Created using genetic engineering to produce specific antigenic proteins of the pathogen.
   • Examples: Hepatitis B, Recombinant Influenza Vaccine, HPV.

7. Virus-Like Particle (VLP) Vaccines:

   • Contain proteins that mimic the virus structure without containing the virus's genetic material.
   • Examples: HPV, Hepatitis B (some versions).

8. RNA/DNA Vaccines:

   • Contains genetic material (mRNA or DNA) encoding the pathogen's antigen. Cells use this genetic code to produce the antigen and trigger an immune response.
   • Examples: COVID-19 mRNA vaccines (Pfizer-BioNTech, Moderna).

9. Vector-Based Vaccines:

   • Use a virus (vector) to deliver genetic material encoding the antigen. The vector is harmless and cannot cause disease.
   • Examples: COVID-19 vaccines using adenovirus vectors (AstraZeneca, Johnson & Johnson).

Each type of antigenic preparation serves to expose the immune system to the pathogen in a safe manner, leading to immunity without causing illness.