Vaccine types Flashcards
What is a live attenuated vaccine?
Vaccine uses a live, but weakened virus. Which has been passed through several cell lines until the pathogenic features have been lost
The virus should be immunogenic enough to stimulate an immune response, but should ideally not be able to cause disease itself
This is the “best” vaccine type, as it stimulates the strongest immune response. However, it cannot be given to high risk patient groups
What is an inactivated whole cell vaccine?
Vaccine uses a “killed” virus.
Virus is neutralised by a chemical or physical process, which means it can no longer replicate
Examples:
Hepatitis A
Rabies
Polio (Salk)
What are benefits of inactivated whole cell vaccines?
cannot cause disease
can be given to more patients groups e.g pregnant/ immunocompromised
What are the drawbacks of inactivated whole cell vaccines?
Less immunogenic than live vaccines - booster vaccines doses are commonly required
What is an inactivated toxoid vaccine?
Bacteria may not cause disease themselves, but rather it is the toxin they produce which causes disease
The toxin can be modified so it is no longer toxigenic, but can provoke an immune response which protects against the toxin in the future
Examples:
Diphtheria
Tetanus
Pertussis
What is a subunit recombinant vaccine?
Vaccines do not need to target the entire virus, just the key components.
For example, Hepatitis B virus requires a specific surface antigen to enter liver cells. Therefore a vaccine is made that targets this specific receptor, so the immune system can produce antibodies to neutralise this
Examples:
Hepatitis B
What is a polysaccharide vaccine vaccine?
A polysaccharide is a molecule which is a long chain carbohydrate, designed to appear like a foreign molecule, and stimulate the immune system
These vaccines are poorly immunogenic, requiring multiple doses
Examples:
Meningococcal
Pneumococcal
What is a polysaccharide conjugate vaccine?
A polysaccharide is a molecule which is a long chain carbohydrate, designed to appear like a foreign molecule, and stimulate the immune system
A bacterial protein can be joined (conjugated) to this chain, to also help further stimulate the immune system
These vaccines are poorly immunogenic, requiring multiple doses
Examples:
Meningococcal
Pneumococcal
Haemophilus Influenzae
What is an adenovirus vector vaccine?
Adenovirus is a very common human pathogen, with everyone having previously been infected
The DNA can be removed from Adenovirus, leaving the “shell” of the virus intact, for use as a vector.
New DNA can be inserted into the “shell” which codes for the virus you are wanting to protect against
The Adenovirus “shell” is used to enter human cells, which then releases the new DNA into the host cells
The host cells then uses this foreign DNA to make viral proteins, and triggers the immune response
Examples:
SARS-CoV-2 (Astra-Zeneca)
What is an mRNA vaccine?
mRNA codes for viral proteins
mRNA coding for a specific viral target can be injected into a patient
This is taken up by host cells
Viral proteins are then generated using this mRNA template
This then triggers an immune response
This is more modern vaccine technology. The benefits are mRNA vaccines can be edited more quickly, to help respond to mutations and future outbreaks more quickly
Examples:
SARS-CoV-2 (Moderna/ Pfizer)
When considering suitability of a vaccine, what are the main characteristics we look at?
Protective effect - the amount by which the vaccines reduce severe disease, prevent hospital admission, and death.
Duration of protection
Speed of protection
Side-effects
Eligible patients
