Question

Outline and explain the principle of population vaccination.

Answer 1

Introduction

Immunity is the ability of the human body to tolerate against the non-self-material and eliminate them. It provides protection from various infectious disease as most of the microbes are identified as foreign body by the immune system. There are two basic mechanism for acquiring immunity active and passive.

• Active immunity provides protection produced by the person’s own body, and usually the protection is permanent.
• Passive immunity are transferred from another human or animal, this type of immunity provides protection that decrease with time.

Antigens are live or attenuated substance capable of inducing an immune response, which involves the production of molecules by B lymphocytes called antibodies which helps to eliminate the foreign substances.

Vaccination

Vaccination enhance the ability of immune system to fight against certain infections caused by the microbes. It is an effective way to decrease morbidity and mortality rate of infectious diseases in a population.

Principle of vaccination is inducing protective immune response by mimicking the interaction of pathogens with human immune system. Vaccine can be antigenic protein, inactivated or weak live pathogen. On administrating, our body produces antibodies and memory B-cell and memory T-cell. So when a person is exposed to pathogenic conditions, the memory cells induce the production of lymphocytes and antibodies that kills the pathogens and provide immunity.The more similar a vaccine is to disease causing pathogens the better the immune response.

Types of Vaccine

1. Live attenuated Vaccine: They are produced by modifying a disease- causing virus or bacterium. The resulting vaccine organism retains the ability to replicate and produce immunity, but usually does not cause illness. Live vaccine used to protect against diseases like Measles, mumps, rubella, Rotavirus, Chicken pox

2. Inactivated Vaccine: They are composed of either whole viruses or bacteria, or fractions of either. Inactivated vaccines usually don’t provide protection as that of live vaccines. So a several doses over time is required to boost the immunity. Inactive vaccines are used against Hepatitis A, Flu, Polio, Rabies.

3. Subunit, recombinant, polysaccharide and conjugate vaccines: They contain a pieces of pathogens that provoke an immune response. The specific protein is isolated and presented as an antigen to the same pathogen. The conjugate vaccines are made using pieces of bacteria, the protein is linked to a carrier protein and used as a vaccine. These vaccines are used against Hepatitis B, HPV, Pneumococcal diseases, Shingles.

4. Toxoid Vaccine: Some diseases are caused by bacterial toxins. Eg.,tetanus caused by bacteria, Clostridium tetani. Vaccines are made by inactivating the toxins that causes disease symptoms.