Immunization and Vaccination | CHAPTER 7 | Microbiology & Parasitology for Nurses

Immunization and Vaccination – Basic microbiology, parasitology, and immunology; nature, reproduction, growth, and transmission of common microorganisms and parasites in Bangladesh; prevention including universal precaution and immunization, control, sterilization, and disinfection; and specimen collections and examination. Students will have an understanding of common organisms and parasites caused human diseases and acquire knowledge about the prevention and control of those organisms.

Immunization and Vaccination

Definition of Immunization

According to 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.

Vaccination:

Injection of a killed microbe in order to stimulate the immune system against the microbe, thereby preventing disease. Vaccinations, or immunizations, work by stimulating the immune system, the natural disease-fighting system of the body.

Definition of Vaccine

According to WHO

A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins.

Or

Any biological products prepared from microorganism that is useful in the prevention and treatment of disease is called vaccine.

Or

Vaccines are immuno-biological substances which are introduced to the body of a person or other animals to produce immunity against a specific disease.

Classification of Vaccine

Live attenuated vaccine

Bacterial:

• BCG vaccine (for tuberculosis).
• Typhoid oral.
• Plague.

Viral:

• Oral polio vaccine.
• Yellow fever
• Rubella
• Mumps
• Influenza

Rickettsial:

• Epidemic Typhus

Inactivated or killed vaccine

Bacterial:

• Pertussis vaccine (for whooping cough).
• Cholera vaccine.
• Typhoid vaccine.
• Plague vaccine.

Viral:

• Salk vaccine (Polio).
• Rabies
• Influenza.
• Hepatitis B

Toxoids

Bacterial:

• Tetanus toxoid – Tetanus.
• Diphtheria toxoid – Diphtheria

Extracted cellular fractions

Meningococal vaccine.

Pneumococcal vaccine.

Combination

• DPT-Diphtheria, Pertussis, Tetanus.
• MMR-Measles, Mumps, Rubella.
• DT.
• DP.
• DPT with typhoid vaccine.
• DPTP (DPT + inactivated polio).

Recombinant vaccine

More recent preparations are subunit vaccine and recombinant vaccine, e.g. recombinar hepatitis-B vaccine.

Hazards of Immunization

A. Reaction inherent to inoculation

It may be

• Local reactions
• General reactions.

a) Local Reaction:

• Pain
• Swelling
• Tenderness
• Small nodules.
• Sterile abscess.

b) General reaction:

• Fever.
• Anorexia
• Malaise
• Headache

B. Reaction due to faulty techniques

a) No immunity (inadequate inactivation’s of microbe).

b) Hepatitis – B

c) Strepto and staphylococcal

d) Local abscess

C. Reaction due to hypersensivity

a) Anaphylactic shock:

• Bronchospasm
• Dysponea
• Pallor
• Hypotension
• Collapse

b) Serum sickness:

• Fever
• Rash
• Oedema

Difference between Live Vaccine and Killed Vaccine

Properties of a Good Candidate Vaccine

• The organism should be a significant pathogen.
• It should exist in one serotype.
• Should have powerful immunogenic property & the antibody should be able to block infection & stop systemic spread.
• It should not have oncogenic property.
• The vaccine should be heat stable.

Advantages of Live Vaccine

Live vaccines are more potent than killed vaccines, because:

• Live organisms multiply in the host and the resulting antigenic dose is larger than what is injected.
• Live vaccines have all major and minor antigenic components.
• Live vaccines engage certain tissues of the body.
• There may be other mechanisms such as the persistence of latent virus.

Single dose is adequate.

No need of adjuvant.

Duration of immunity is longer

Greater effectiveness of protection

Both cell mediated and antibody mediated immunities are produced

Disadvantages of Live Vaccine

• Reversion to virulence is possible.
• Excretion of vaccine virus and transmission to to non-immune contacts is possible.
• Interference by other viruses in host is possible

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