principles of immunisation mw % + Flashcards
Describe the principles of active immunisation?
- Active immunity is part of the adaptive immune system.
- It has a natural and artificial pathways.
- In active immunity, the microbial antigen (vaccine) is administerated to a person, leads to recovery and its specific to the antigen
- immunological memory is present
Define what is meant by the term vaccination?
Vaccination is the administration of antigenic material to stimulate an individual’s immune system to develop adaptive immunity to a pathogen.
Describe the contra-indications (when not to take them) to vaccination?
- Temporary
- Febrile illness (fever symptoms)
- Pregnancy
2.Permanent
- Allergy
- Immunocompromised
Describe the concept of herd immunity?
Primary aim of vaccination is to protect the individual who receives the vaccination, vaccinated individuals are less likely to be a source of infection to others so reduces the risk of unvaccinated individuals being exposed to infection.
Describe the vaccination schedules for children?
Children are vaccinated with various types of vaccines unti the age of 18 years. There is also non-routine vaccines at birth such as Tuberculosis if the child is more likely to come into contact with the diease.
Describe the vaccines that may need to be given to travellers?
- Hepatitis A
- Typhoid
- Cholera
- Yellow fever
- Rabies
Describe the principles of passive immunisation?
- Serum (antibody) from immune individual is adminstrated to unaffected individual.
- Leads to recovey
- its specific
- No memory
What are the advantages and disadvantges of passive immunisation?
Advantages:
- Gives immediate protection
Disadvantages
- Short term effect – no immunological memory
- Serum sickness – incoming antibody is recognised as a foreign antigen by the recipient and results in anaphylaxis.
What are the advantages and disadvantges of active immunisation?
Antigen (whole organism or part of it) stimulates immune response.
Advantages:
- Long term immunity – may be lifelong
- Immunological memory
Disadvantages:
- No immediate effect (slow acting), but faster and better response to next antigenic encounter.
What are the types of vaccines?
- Conventional vaccines
- Subunit vaccines (just antigen)
- Toxoid (just toxin)
Describe conventional vaccines?
Kill whole organism:
- Target organism (e.g. polio virus) is killed.
- Virus must be heat killed effectively – any live virus can result in vaccine-related disease
Attenuated whole organism (mainly viruses)
An avirulent strain of target organism is isolated
- Can be very powerful and better than killed
- Simulate natural infection
- Reversion back to virulent form
Describe a subunit vaccine?
A subunit vaccine presents an antigen to the immune system without introducing whole viral particles
Recombinant protein: a protein encoded by a gene that has been cloned in a system that supports expression of the gene and translation of messenger RNA
- Generally very safe
- Not very immunogenic without an effective adjuvant (substance which enhances immunological response to antigen)
Describe Toxoid (Modified Toxin) vaccine?
- Toxin is treated with formalin (antiseptic)
- Toxoid retains antigenicity but has no toxic activity
- Only induces immunity against the toxin, not the organism that produces it.
What makes a good vaccine?
- Potent antibody response – high antibody titers
- Potent CD8+ cytotoxic T cell response
- CD4+ T helper response
- Memory
What are the challenges facing vaccines?
- Conventional vaccines cannot elicit immunity against all infectious disease.
- Antigenic shift and drift, and strain diversity in general
- Persistence – ideally vaccines should give life long protection
The young and the old
•Neonates
- Vulnerability <18–24 months to encapsulated bacteria such as pneumococcus, Hib and meningococcus
- Fewer FDC, and B cells do not express costimulatory molecules
- Short term antibody production
•Elderly
- Reduced efficacy or responsiveness to vaccination
- Oligoclonal responses lacking specificity
- Reduced plasma cell survival niches
