Lecture 7- Vaccination Flashcards
Immunisation =
process of rendering a person immune or resistant to an infectious disease. Can be naturally acquired or artificially induced as a result of vaccination.
Vaccination
= process of stimulating protective adaptive immunity against a microbe by exposure to its nonpathogenic forms called vaccines.
Vaccine =
Live attenuated or killed organisms or microbial components (proteins, modified toxins or RNA) given for the prevention of infectious diseases. Vaccines can also be given as a therapy as a form of postexposure prophylaxis (PEP) following the exposure to a pathogen known to induce a disease.
active vs passive immunity
- Active= best form of vaccination
- Only active will lead to long term protection due to the production of memory cells
types of vaccine
live attenuated virus/bacteria
inactivated virus
inactivated toxin
conjugate/ subunit
live attenuated virus
rotavirus
influenza
MMR
varicella zoster virus
live attenuated bacteria
BCG
inactivated virus
HepA
influenza
rabies
inactivated toxin
diptheria, tetanus
conguhate
HepB, HiB
pneumomococaal and meningococcal
advantages and disadvantages of live vaccines
advantages and disadvantages of inactivates/subunit vaccines
Target population
Route of vaccine administration
Immune mechanism
- APC (dendritic) engulf antigens from vaccine- initiating immune response
- Stimulate CD8 and B cell response
- Cytotoxic and humoral immunity
- Long term protection –> memory B cells and plasma cells
Goals of active immunisation
- Long lasting immune protection
- Protective antibody (IgM, IgG)
- Vaccine-specific T cell response (viruses)
- Immunological memory to allow a quicker and more effective production of the above
- Herd immunity
Herd immunity
“‘Herd immunity’, also known as ‘population immunity’, is the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection. WHO supports achieving ‘herd immunity’ through vaccination, not by allowing a disease to spread through any segment of the population, as this would result in unnecessary cases and deaths”
Importance:
- Reduces or abolishes the circulation of the pathogen
- Protects the immunocompromised patients
- Protects the poor responders to vaccines (2-10%)
Immunisations strategies
Childhood immunisation (8 weeks up to 14 yo)
- Routine immunisation (see table)
- Non-routine immunisation
Adult immunisation
- >65yo
- Travelers
- Medical conditions
Absolute contraindications to active immunisation
- Any severe, local or generalized reaction to a previous dose of vaccine (anaphylaxis)
- Moderate and severe illness (with fever >38.5∘C)
Special considerations for live vaccines
- Infants born to a mother who received immunosuppressive biological therapy during pregnancy (no live vaccines)
- Pregnant women (no live vaccines)
- Allergy to egg (Influenza and Yellow fever vaccines)
- Allergy to gelatin (MMR, varicella, shingles)
- Allergy to neomycin, streptomycin, or polymyxin B (pertussis, polio, Tetanus, Shingles, varicella, MMR)
No LIVE vaccine in immunocompromised individuals
- Those with primary or acquired immunodeficiency affecting cell immunity
- Are within 6 months of having received chemotherapy/radiotherapy for malignant and non-malignant diseases
- Have received bone marrow transplantation
- Are receiving or have received high doses of immunosuppressive therapy in the past three months (corticosteroids, methotrexate, azathioprine) and in the past 12 months (biological therapies = monoclonal antibodies)
Adverse effects
- Common : local reactions, rashes, fever, headache
- Very rare: anaphylaxis* (1: 1 million) or syncope (fainting)
False contraindications to routine vaccines
- Atopy and food intolerance
- Prematurity
- Currently breast-feeding or being breast-fed
- Current antibiotic or topical corticosteroid therapy
- Personal history of febrile convulsions or epilepsy
- Underweight or past the age of vaccine recommended by the schedule
- Pregnant mother (No LIVE vaccine)
- Egg allergy and MMR vaccine
