Immunization

Childhood Immunization

Dr.Mazin Al-Jadiry October 12th 2015

vaccination

Immunization saves lives
Immunization saves the lives of approximately 3 million people each year, all over the world.

Figure 17.1 Effect of immunization-overview

Learning objectives
Define immunity, immunization, immunizing agents & the types of active and passive immunization Know the factors that affect the response to vaccinations Understand the goal of immunization Define the types of vaccine failure Recognize the adverse effects & general C/I of vaccination To be aware of false contraindication of vaccinations

Immunity

Immunity is the ability of the human body to protect itself from infectious disease. Natural or non-specific immunity is present from birth and includes: physical barriers (e.g. intact skin and mucous membranes) chemical barriers (e.g. gastric acid, digestive enzymes and bacteriostatic fatty acids of the skin) phagocytic cells complement system. Acquired immunity is generally specific to a single organism or to a group of closely related organisms.


Immunization-Definition (WHO)
Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease

Immunization

Two Artificial Methods of Immunity Active immunization Administration of antigens so patient actively aquire a protective immune response Passive immunization Individual acquires immunity through the transfer of antibodies formed by immune individual or animal

Active immunity

Protection that is produced by an individual’s own immune system and is usually long-lasting. Active immunity can be acquired by natural disease or by vaccination. Vaccines generally provide immunity similar to that provided by the natural infection, but without the risk from the disease or its complications.

Immunization

Active Immunization Vaccine types Attenuated (live) vaccines Use pathogens with reduced virulence Can result in mild infections Active microbes stimulate a strong immune response Can provide contact immunity Modified microbes may retain enough residual virulence to cause disease

Immunization

Active ImmunizationVaccine typesInactivated (killed) vaccinesWhole-agent vaccinesSubunit vaccinesBoth safer than live vaccinesMicrobes don’t provide many antigenic molecules to stimulate the immune responseOften contain adjuvants Chemicals added to increase effective antigenicity

Immunization

Active Immunization Vaccine types Toxoid vaccines Chemically or thermally modified toxins used to stimulate immunity Useful for some bacterial diseases Stimulate antibody-mediated immunity Require multiple doses because they possess few antigenic determinants



Passive immunity
Passive immunity is protection provided from the transfer of antibodies from immune individuals, Most common: Across the placenta Less often: Blood transfusion & blood products including immunoglobulin This protection is temporary – commonly for only a few weeks or months

Immunizing agents

Vaccine: A preparation of proteins, polysaccharides, or nucleic acids of pathogens that are delivered to the immune system to induce active immunization. Toxoid (detoxified toxins) : A modified bacterial toxin that has been made nontoxic but retains the capacity to stimulate the formation of antitoxin and induce active immunization.
?
?

Immunizing agents cont.

Immune globulin: An antibody-containing solution derived from human blood obtained by large pools of plasma and used for passive immunization (primarily for the maintenance of immunity of immunodeficient persons). Antitoxin: An antibody derived from the serum of humans or animals after stimulation with specific antigens; used to provide passive immunity.
?
?

Goal of Immunization

Immediate goal of immunization is to prevent disease in individuals Ultimate goal is to eliminate or even eradicate a communicable disease.

Herd Immunity OR community immunity

The risk of infection among susceptible individuals in a population is reduced by the presence and proximity of immune individuals "indirect protection" or a "herd effect" In this way transmission falls or stops without universal immunity. The more children in a community that are fully immunized, the more everyone is safe.
Immunization can protect the unprotected

Types of Active Immunization

The current approaches to active immunization are the use of live-attenuated infectious agents (Measles, mumps, rubella, Oral Polio Vaccine and rotavirus vaccine) Inactivated or detoxified agents, their extracts, or specific recombinant products, include: Inactivated whole organisms (e.g., whole-cell pertussis) Detoxified exotoxins (e.g., tetanus and diphtheria toxoids) Purified protein antigens (e.g., acellular pertussis & hepatitis B) Polysaccharides (e.g., capsular meningococcal vaccine) Capsular polysaccharides conjugated to carrier proteins (e.g., Hib and pneumococcal conjugate vaccines) Components of the organism (e.g., subunit influenza vaccine).

Types of Active Immunization

BCG
Live attenuated
Bacterial
Pertusis, typhoid & cholera
Killed whole organism
Inactivated
Tetanus, diphtheria
Toxoids
Capsular meningococcal
Polysaccharides
Acellular pertussis
Purified protein antigens
Hib & pneumococcal conjugate vaccines
Capsular polysaccharides conjugated to carrier proteins
OPV, MMR, Rotavirus
Live attenuated
Viral
IPV, hepatitis A
Inactivated whole organisms
Inactivated
Hepatitis B
Purified protein antigens
Subunit influenza vaccine
Components of the organism


Active Immunization

OPV: Oral Polio Vaccine, IPV: Inactivated Polio Vaccine

Passive Immunization

Passive Immunization

Specific equine antibodies (IM) Botulism antitoxin Diphtheria antitoxin Tetanus antitoxin Snake & spider anti-venom

Factors that affect the response to vaccinations

Chemical and physical state of the antigen Host factors (age, nutrition, and pre-existing antibody) Presence of high concentrations of maternal antibody in the first few months of life and the relative immaturity of the immune response impair the initial immune response to some vaccines Route of administration Parentally administered vaccines may not induce mucosal secretory IgA, whereas vaccines given orally are likely to do so. The immunogenicity of some vaccines is reduced when not given by the proper route. For example, subcutaneous hepatitis B vaccine.

Rights of vaccine Administration

the right patient the right vaccine the right time* the right dosage the right route, needle length, and technique the right site; and the right documentation *(includes administering at the correct age, the appropriate interval, and before vaccine or diluent expires)

Route of administration

Route of administration

Route of administration

Route of administration
I.M.

Route of administration

S.C.

Route of administration

I.D.

Route of administration

Route of administration

Vaccine failure

No vaccine offers 100% protection and a small proportion of individuals get infected despite vaccination. Vaccines can fail in two main ways – primary or secondary vaccine failures:

Vaccine failure

Primary failure occurs when an individual fails to make an initial immunological response to the vaccine. Infection can therefore occur at any point after vaccination. e.g. is the 5–10% of children who do not respond to the measles component of the first dose of MMR. The risk of measles in such children is reduced by offering an additional dose of vaccine, usually before school entry.

Vaccine failure

Secondary failure occurs when an individual responds initially but then protection decrease over time. Individuals who acquire infection despite vaccination may have a modified, milder form of disease and are less likely to suffer serious complications than those who have never been vaccinated. pertussis vaccine, when protection against whooping cough after three doses is initially high but declines as a child gets older. A fourth (booster) dose is given to improve protection during the school years.

Principles in Vaccination

Live vaccines, unless given simultaneously, should not be given within a month of each other. Vaccines should not be given within 3 months of receiving a gamma globulin product Premature infants should be kept on the same schedule as full-term infants; split doses of vaccine are unnecessary.

Principles in Vaccination

Lapsed immunizations do not require reinstitution of an entire vaccine series; immunizations should be given as though the proper interval has elapsed Children whose vaccination status is uncertain should be considered unimmunized and should be given appropriate vaccines. There are no contraindications to simultaneous administration of multiple vaccines.

Adverse events after vaccination

Vaccine components can cause allergic reactions in some recipients, the most common extraneous allergen is egg protein from vaccines prepared in embryonated eggs, such as measles, mumps, influenza, and yellow fever vaccines. Reactions may be local or systemic, including anaphylaxis and urticaria. Local or systemic reactions result from too frequent administration of some vaccines, such as tetanus toxoids or rabies, and are probably caused by antigen-antibody complexes.

Booster doses

For most vaccines, the immunity against a particular pathogen has a tendency to wear off over time. A periodic ''booster'' administration to be given in order to strengthen and lengthen the duration of immunity

General Contraindications

Serious allergic reaction (e.g., anaphylaxis) after a previous vaccine dose Serious allergic reaction (e.g., anaphylaxis) to a vaccine component Moderate or severe illnesses with or without a fever (more than 38 C )

False contraindications to vaccination

Mild acute illness with low grade fever or mild diarrhea Mild to moderate local reaction (soreness, redness, swelling) after a dose of an injectable antigen Current antibiotic therapy Prematurity Breast feeding Pregnancy of mother or household contact Malnutrition A history of penicillin or other non specific allergy Family history of convulsion in a child considered for pertussis or measles vaccination

Thanks