Intro to Vaccines COPY Flashcards
Immunisation definition
Process of rendering someone immune or resistant to an infectious disease.
Can be naturally acquired or artificially induced
Vaccination definition
Stimulating protective adaptive immunity by exposure to nonpathogenic forms called vaccines
Vaccine definition
Live attenuated/killed organisms or microbial components given for prevention of infectious disease.
Can be given as postexposure prophylaxis after exposure to disease causing pathogen
Two types of immunisation
Active (Natural infection vs artificial vaccine)
Passive (natural from mother vs artificial antibodies given)
Different protection with different types of immunisation
Long term protection for ACTIVE immunity
Short term protection for PASSIVE immunity
Current problems active immunisation
Lower uptake of childhood measles vaccine
UK no longer measles free
Types of vaccine
Live attenuated virus/bacteria (eg rotavirus, influenza, MMR, BCG)
Inactivated virus (Hep A, rabies)
toxin (diphtheria, tetanus)
subunit (Hep B, meningococcal)
Live vs inactive vaccine
Live:
Advantages - single/fewer doses, reproduce natural infection, good protection
Disadvantages - Reversion to virulent wild virus (cause harm), storage issues
Inactive
Advantages - safe, not mutation, stable
Disadvantages - Multiple doses/boosters needed, less effective than live, variable efficacy, high conc required
Target population of vaccines
babies (>8 weeks)
Teens (>12-14 years)
Adults (>65)
OR ANY AGE if underlying conditions
Routes of vaccines
Oral (rotavirus) Nasal spray (influenza) Injectable vaccine (Deltoid area/anterolateral leg of thigh in infant)
Mechanism of vaccination
Vaccine antigens and Adjuvant (contain danger signals)
MHC class 2 present antigens to TCR on CD4+
Cd4+ cell activated
PRR recognise Adjuvant
Stimulates T helper cells and CD8+ cell
MHC class 1 presents to CD8+ and activates
CD8+ stimulates effector T cells and memory cells
T helper cell stimulates B cells to proliferate and form memory cells and plasma cell that produce antibody
Goals of active immunisation
Long lasting immunity: IgA, IgG, Vaccine specific T cell response, immunological memory
QUICKER and more EFFECTIVE production of IgG
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Herd immunity
What is herd immunity
Indirect protection from infectious disease that happens when a population is immune via vaccination or previous infection.
WHO supports achieving herd immunity via vaccination and not allowing a disease to spread through a population
Importance herd immunity
Abolishes circulation of pathogen
Protects immunocompromised
Protects those that respond poorly to vaccines
What does herd immunity threshold depend on
The R0 value (reproduction) value of disease
eg. if high R0 value (highly infectious) would need high percentage of immunity to reach herd immunity threshold