WEEK 9: VACCINES Flashcards
What is a vaccine?
It is a modified form or weakened form or a component of a microbe that is used to elicit protective immunity to a subsequent exposure to the pathogenic (wild type) form of that microbe
Do we have vaccines for fungal diseases?
no.
Do we have vaccines for parasitic diseases?
yes.
What 2 diseases have been eradicated by vaccinations?
variola major (smallpox) and rinderpest
What is the R0 value?
The R0 is the number of people that one sick person will infect (on average). It varies from one pathogen to another
What is herd immunity?
Herd immunity is when a threshold of individuals have been vaccinated or have been infected naturally that results in a level of community immunity in a population that limits the movement of the virus or bacterial pathogen.
What is active immunity?
- giving the recipient a modified form of the pathogen or material derived from it that induces long term immunity to the disease
- long term protection
What is passive immunity?
- giving the products of the immune response i.e. antibodies or immune cells, into the recipient
- short term protection
Give examples of passive vaccines.
Varicella-zoster vaccine, Lassa virus vaccine, Ebola virus vaccine (Zmapp)
What are the key immunological requirements of an effective vaccine? (3)
- induce appropriate immune response (includes neutralising antibodies, CD4+ T cells responses, CD8+ T cell responses)
- the immune responses that need to be elicited to achieve protection = correlates of immunity
- vaccinated individuals must be protected against the disease caused by the virulent of the specific antigen
What are the key safety and economic requirements of an effective vaccine?
- Safety: no disease, minimal side effects
- Induces protective immunity in the population
- Protection must be long lasting
- Other factors:
- Low cost (WHO suggests <£1)
- Genetic stability
- Storage; preferably no cold chain
- Route of administration (oral, needle, IV,intramuscular)
What is an attenuated vaccine?
A live vaccine. Virus retains antigenicity but loses pathogenicity.
How is attenuated vaccine made?
take the wild type pathogen and either passage it through cells or an animal model. Changes from wild type and attenuates. Virus retains antigenicity but loses pathogenicity.
What is a subunit vaccine?
A subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response
How is an inactivated vaccine produced?
Grow virus i cell culture (mammalian cell culture or MCACKS??). Isolate virus and inactive virus.
Inactivated through chemical procedures to preserve antigenicity and eliminate infectivity simultaneously.
