Types of Immunization

 Types of Immunization

1. Active Immunization

2. Passive Immunization

3. Combined passive and active immunization

1. Active immunization (by vaccine)

Active immunization is done by use of vaccines.

The vaccines may be live attenuated, killed or an ideal vaccine is that;

1. Containing enough antigen to protect against infection.

2. Doesn't cause disease in vaccinated person

Types of Vaccine

1. Live attenuated vaccine

2. Inactivated or killed vaccine

3. Toxoids

4. Subunit vaccine; use antigenic portion of pathogen.

5. Conjugate vaccines

6. DNA vaccine

7. Autogenous vaccine

8. Combined vaccines

1. Live attenuated vaccines

For example; 

BCG (Bacille Calmette Gurein)

OPV (oral polio vaccine)

Oral typhoid vaccine

Yellow fever vaccine

Measles vaccine

Mumps vaccine

Rubella vaccine

Varicella vaccine

Live attenuated vaccines is those vaccine when produced into the body produce artificial active immunization.

These are prepared from live attenuated organism. Due to attenuation process, the organism lost their capacity to produce disease.

Attenuation of organisms is achieved by;

1. Aging of culture

2. Culture of high temperature

3. Passage through another host species

4. Drying, for example; rabies vaccine

5. Selecting of mutant (temperature sensitive)

2. Inactive and Killed vaccine

These are prepared from killed organisms.

Organisms are killed by heat, formalin, phenol, alcohol, ultraviolet light and photodynamic inactivation.

For example; 

Whooping cough, Typhoid (Typhoid and paratyphoid fever vaccine)

Killed polio vaccine and Influenza vaccine

Plague vaccine, Cholera vaccine, Hepatitis A vaccine

3. Toxoids

These are exotoxins produced by certain microorganisms which are treated with formalin to destroy their toxicity but retaining their immunogenicity.

Toxoids are usually prepared by inactivating exotoxins with formalin or heat.

For example; 

Diphtheria toxoids vaccine

Tetanus toxoid vaccine

4. Subunit vaccine

A subunit vaccine is a vaccine that contains only the minimal microbial elements necessary to stimulate long-lasting protective immune response.

For example;

Hepatitis B vaccine

Lyme disease vaccine

For example; A vaccine containing pili of N. gonorrhoea could stimulate the immune system to produce antibodies that would attach to the pili of N. gonorrhoea and prevent its attachment to genitourinary cell and hence prevents gonorrhoea infection.

5.  Conjugate vaccines

These are vaccines made by conjugating bacterial capsular antigen to molecules that stimulate the immune system to produce antibodies against less antigenic capsular antigens.

For example;

Hib conjugate vaccine

Meningococcal vaccine

Pneumococcal vaccine 

6. DNA Vaccines

In such vaccines a particular gene from pathogen is inserted into the plasmid of bacteria and- these plasmids are then injected into the skin or muscle tissue.

Inside host cells, the genes direct the synthesis of particular microbial protein (antigen).

The immune system then produces antibodies against these proteins/ antigens and thus protect the individual from infection.

7. Autogenous Vaccines

These are vaccines prepared from the bacteria isolated from the localized infection, such as; Staphylococcal bolis.

The pathogens are killed and then injected into the se person to induced production of more antibodies against that pathogen.

8. Combined vaccines

This is mixture of two or more types of vaccines.

For example; 

DPT (Diphtheria, pertussis, and tetanus)

Polio, and influenza vaccines are prepared this way.

2. Passive Immunization 

Passive immunization is administration of purified antibodies or serum containing antibodies to provide, rapid and temporary protection at the time of emergency (i.e when individuals immune system is unable to provide resistance against infection).

For example; newborn receive natural passive immunity from mother's antibodies (immunoglobulins) that can cross placenta IgG or it is also present in mother's milk IgA.

Passive immunization is done by sera which contains antibodies - it involves human sera and animal sera.

It is considered necessary to give immediate protection to an anticipated infection.

For example;

Passive immunization against tetanus, hepatitis B and rabies.

Passive immunization is used to;

1. Prevent disease after a known exposure.

For example; needle stick injury with blood that is contaminated with Hepatitis B virus.

2. Protect immunodeficient individuals who are incapable of making an immune response.

Three types of preparation are available for passive Immunization;

1. Pooled immunoglobulin

2. Specific immunoglobulin

3. Homologous and heterologous sera

1. Pooled immunoglobulin

It is prepared from plasma of approximately a thousand or more blood donors.

Containing high level of antibodies.

Human normal immunoglobulin (HNIG) is used in short term prophylaxis against hepatitis A and measles.

2. Specific immunoglobulin

It is prepared from serum of patients who are recovering from infection.

Specific immunoglobulins are available against tetanus as human tetanus immunoglobulin (HIIG).

Hepatitis B as hepatitis B human immunoglobulin (HBIG)

Rabies as human rabies immunoglobulin (HRIG)

Varicella zoster as zoster immunoglobulin (ZIG).

3. Homologous and heterologous sera

Antibacterial, antiviral, antibodies in human (homologous) or animal (heterologous) serum are injected to provide temporary protection against infection.

3. Combined passive and active immunization

In some diseases (such as diphtheria, tetanus, rabies) passive immunization is undertaken in combination with inactivated vaccine product's in order to provide both immediate, passive immunity which is temporary and slowly developing active immunity which lasts for longer periods of time.

Both the preparation should be injected at different sites in a body.