Vaccine

Expanded Program on Immunization (EPI) 2022 Notes

Primary Health Care Components

• Education: Involves educating communities about prevailing health problems, methods for identifying them, and strategies for prevention and control.

• Disease Prevention: Focuses on the prevention and control of locally endemic diseases.

• Expanded Programme of Immunization: Aims to immunize against major infectious diseases.

• Maternal and Child Health Care: Includes family planning services.

• Essential Drugs Arrangement: Ensures the availability of essential medications.

• Nutritional Support: Provides nutritional food supplements, ensuring an adequate supply of safe and basic nutrition.

• Treatment: Involves treating communicable and non-communicable diseases and promoting mental health.

• Safe Water and Sanitation: Essential components for overall health.

• Cold Chain Maintenance: Necessary for the proper storage and transportation of vaccines.

• Population Aging: Considerations within primary health care practices for an aging population.

Principles of Vaccination

• Immunity:

  • Definitions:

  • Self vs. Non-Self: Differentiation between body’s own cells and foreign invaders.

  • Protection from Infectious Diseases: Indicated by the presence of specific antibodies.

  • Specificity: Immunity is usually very specific to a single organism.

Types of Immunity

• Active Immunity:

  • Description: Immunity produced by an individual's own immune system.

  • Duration: Generally, it is permanent.

• Passive Immunity:

  • Description: Immunity transferred from another individual (human or animal).

  • Duration: Temporarily provided, tends to wane with time.

Antigens and Antibodies

• Antigen:

  • Definition: A live or inactivated substance (e.g., protein, polysaccharide) capable of inducing an immune response.

• Antibody:

  • Definition: A protein molecule produced by B lymphocytes that plays a role in eliminating antigens.

Sources of Passive Immunity

• Sources:

  • Blood products and plasma.

  • Homologous pooled human antibody (immune globulin).

  • Homologous human hyperimmune globulin.

  • Heterologous hyperimmune serum (antitoxin).

Monoclonal Antibodies

• Monoclonal Antibody:

  • Definition: Derived from a single type of antibody-producing B cell, specific to one antigen or closely related antigens.

  • Uses: Diagnostic and therapeutic applications for cancers, autoimmune, and infectious diseases.

Vaccination and Immune Response

• Vaccination:

  • Definition: Administration of a vaccine to produce active immunity.

  • Immunological Memory: Similar to natural immunity without the risk of disease.

Classification of Vaccines

• Types:

  • Live Attenuated Vaccines:

  • Description: Contains a weakened form of the virus or bacterium.

  • Features: Must replicate to confer immunity, typically produces a long-lasting immune response with one dose (except oral vaccines).

  • Inactivated Vaccines:

  • Types: Includes whole virals and bacteria, fractional (protein-based), toxoid, and subunit vaccines.

  • Characteristics: Cannot replicate; usually requires multiple doses and immune responses are mostly humoral.

Specific Live Vaccines

• Viral: Include measles, mumps, varicella, zoster, yellow fever, rotavirus, and oral polio.

• Bacterial: Include BCG (tuberculosis) and oral typhoid.

Specific Inactivated Vaccines

• Whole Cell Vaccines:

  • Viral: Polio, hepatitis A, rabies, influenza.

  • Bacterial: Pertussis, typhoid, cholera, plague.

• Fractional Vaccines: Subunit (e.g., hepatitis B, HPV) and toxoid (e.g., tetanus).

Polysaccharide Vaccines

• Types:

  • Pure Polysaccharide Vaccines: Pneumococcal, meningococcal, and salmonella typhi.

  • Conjugate Polysaccharide Vaccines: Haemophilus influenza type B, pneumococcal, and meningococcal.

Immunogenicity of Vaccines

• Pure Polysaccharide Vaccines:

  • Not consistently immunogenic in children under 2; does not provide booster response; conjugation improves immunogenicity.

Expanded Programme on Immunization (EPI)

• Establishment and Goals: Established in 1974, aimed to make vaccines against diphtheria, pertussis, tetanus, poliomyelitis, measles, and tuberculosis available to every child worldwide by 1990.

• Access to Vaccines: Enshrined in Presidential Decree 996 in 1976, to ensure that children and mothers have access to age-recommended vaccines.

• Immunization: Improves individual and communal health by preventing the spread of infectious diseases through antibody stimulation.

Benefits of EPI

• Protection: Simple and effective in protecting individuals and populations from specific diseases.

• Response to Infections: Triggers immune response that allows vaccinated individuals to combat diseases more effectively.

• Post-vaccination Observation: Individuals should remain for 15-30 minutes after vaccination to monitor for rare reactions.

• Side Effects: Potential mild reactions include soreness and fever; severe allergic reactions require emergency intervention.

Specific Health Risks

• Guillain-Barré Syndrome: Associated with tetanus vaccines, however, vaccinated children with the 5-in-1 vaccine are not at higher risk.

• General Vaccine Safety: Vaccines are generally considered safe; risks associated with infections are much greater.

Contraindications for Children

• Aspirin Usage: Should NEVER be given to children under 12 due to the risk of Reye’s syndrome, which can cause severe liver and brain damage.

Definitions of Fully Immunized Child

• Criteria: A fully immunized child has:

  • Received BCG vaccination.

  • Three doses each of DPT, Hib, and HepB vaccines.

  • Three doses of polio vaccine.

  • Two doses of PCV, RV, and one dose of measles vaccine.

• Age Requirement: Must be fully immunized within the first year of life.

Immunization Schedule in Zambia

BCG Vaccination at Birth

• Purpose: Given to protect against severe tuberculosis in infants; neonatal immune systems are still maturing.

Pentavalent Vaccine

• Definition: The 5-in-1 vaccine which protects against diphtheria, tetanus, whooping cough, polio, and Hib disease.

• Administration: Given in a series over time, typically four injections from 2 to 18 months of age.

Diphtheria, Pertussis, and Previous Concerns

• Diphtheria: Caused by bacteria that can obstruct breathing and produce toxic effects.

• Pertussis (Whooping Cough): Causes severe coughing spells in infants.

• Tetanus (Lockjaw): Caused by a bacterial toxin, can result in painful muscle spasms.

• Hepatitis B: Virus spread through contact with infectious body fluids; vaccination is crucial to prevent chronic infections and hepatic disease.

• Haemophilus Influenzae Type B (Hib): Can lead to severe infections in young children; vaccination is important for prevention.

Polio Overview

• Causative Agent: Poliovirus, a member of the enterovirus family.

• Spread: Through contact with infected feces or respiratory droplets.

• Manifestation: Can lead to mild illness or severe paralysis.

• Types of Polio: Wild poliovirus types 1, 2, and 3; type 2 has been eradicated.

Polio Vaccination Types

• Inactivated Polio Vaccine (IPV): Administered through injection; safer for developed regions.

• Oral Polio Vaccine (OPV): Given via mouth; used largely in developing regions, effective in preventing disease spread.

Stages of Poliomyelitis

• Stages include: Prodromal, Acute, Convalescent, and Recovery, which vary in duration and symptoms.

• Pathophysiology: Involves stages from entry through nasopharynx, multiplication in gut, and progression to neurological effects leading to paralysis.

Rotavirus Infection and Vaccination

• Disease Overview: Causes severe diarrhea, especially in young children.

• Vaccine: Administered orally; children receive 2-3 doses based on the vaccine brand.

• Vaccine Safety: Potential side effects include intussusception and allergic reactions; vaccine mitigates severe illness effectively.

Measles Overview

• Viral Infection: Highly contagious; can lead to serious complications and remains a leading cause of global mortality.

• Transmission: Airborne via respiratory droplets; viral load remains infectious on surfaces for prolonged periods.

• Vaccination: Best prevention strategy; MMR and MMRV vaccines provide protection, with high efficacy reported for two doses.

Complications and Side Effects of Measles Vaccine

• Potential Side Effects: Link to low platelet counts or seizures, but generally very safe.

End of Expanded Program on Immunization (EPI) Notes