vaccines Flashcards
what is the difference between active and passive immunisation
active immunisation is when host’s immune system encounters the pathogen and elicits immune response while passive immunisation is the administration of specific Ab for short term immunological protection of the host
what are the types and levels of protection obtained through vaccination
individual protection, herd immunity, global protection, indefinitely shelter future generations from harm
what are the types of vaccines
inactivated
live, attenuated
subunit, recombinant, polysaccharide and conjugate
toxoid
viral vector
mRNA
what are the basic components in a vaccine
immune antigens, suspension fluids, stabilisers, preservatives, emulsifiers/ surfactants, adjuvants
what are the requirements of vaccine
- 100% effective in all age groups
- should provide long term protection after a single application, for a lifetime if possible
- should not have side effects
- should be stable in different conditions (heat, light, transport)
- should be easily accessible and inexpensive
- should protect against more than one diseases at the same time, should be able to simulate both systemic and mucosal immunity
what do vaccines contain and how does it affect the stability of vaccines
vaccines contain proteins, lipids, carbs and nucleic acids
freezing and temperature below 0degC has negative effect on potency of vaccines, should be stored, transported and applied in special conditions
what is a cold chain
temperature controlled supply chain that includes all vaccine related equipment and procedures
what are the characteristics of a cold chain
temperature 2-8degC
vaccine vial or cold chain monitors to track temperature at all points in time
insulated container for transportation
shake test
starts off with manufacturer and ends with provider administrating the vaccine to patient
what are inactivated vaccines and what kind of reponse do they produce
contain bacteria or viruses that has been inactivated by heat or chemically
produces a weak immune response and requires repeated doses
what are examples of inactivated vaccines
polio, hep A, flu shot, rabies
what is the manufacturing process of inactivated vaccines
virus -> live cells -> inactivated by chemicals -> purification and impurity removal -> vaccine stock bulk -> filling and packaging
what are live attenuated vaccines and what kind of response do they produce
maintains antigenicity but loses pathogenicity, similar to natural infection
strong and long lasting immune response
what are examples of live attenuated vaccines
MMR, rotavirus, chicken pox, small pox, yellow fever
what are the disadvantages of live attenuated vaccines
not suitable for immunocompromised and transplant receivers, need to be refrigerated, can become live again and cause host with the vaccine to fall sick
what is the manufacturing process of live attenuated vaccines
forcing virus to grow in unusual conditions -> causes genetic code to change over time within weeks or months -> changes to genetic code makes virus harmless enough to use as vaccine
what are subunit, recombinant, polysaccharide and conjugate vaccines
contains a specific part of the pathogen which can be protein, peptide or polysaccharide
what is the difference between recombinant and conjugate vaccine
recombinant vaccines contain genes that encode the specific antigen or antigens -> once DNA encoding the antigen-containing-vaccine is taken up by cells, Ag can be secreted or stimulate cellular immunity in relation to cell surface
conjugate vaccine contains a weak and a strong antigen
what are examples of recombinant and conjugate vaccines
shingles (recombinant), hep B (recombinant), haemophillus influenzae (conjugate), pertussis aka whopping cough
what are toxoid vaccines and how does it work
toxoid vaccines are preparations whose toxic effects are eliminated as a result of removing exotoxins and endotoxins with formaldehyde at a certain temperature for a period of time
provides immunity by stimulating anti-toxoid Ab and can bind to toxin thus neutralising its toxic effects
what are the disadvantages of toxoid vaccines
- need boosters as immune response not high
- need adjuvant to increase immune response
- difficult to manufacture as want to inactivate toxin but not by too much such that the structure is disrupted and cannot provide adequate immunity
what is the manufacturing process of toxoid vaccines
bacteria secreting toxins or harmful chemicals are grown in culture media -> toxoids which are secreted toxins are inactivated by heat or chemicals -> injecting of entire dose of vaccine as priming vaccination -> induction of immune response -> subsequent booster doses
what are viral vector vaccines
makes use of a vector virus which is a harmless, modified version of a virus
contains DNA spike protein which is a large and highly glycosylated transmembrane protein of the virus
vector viruses are genetic makeup of different viruses or engineered viruses
what is the manufacturing process of viral vector vaccines
spike protein of virus extracted (eg. of COVID-19) -> this genetic material is inserted into unrelated harmless virus that act as a vector -> formulate viral vector vaccine -> when administered and “harmless virus” enter cell -> produces spike protein which stimulates Ab by immune system -> recognises and provides immunity if subsequently infected with actual virus
what are mRNA vaccines
works by introducing a piece of mRNA that corresponds to a viral protein usually found on the virus’ outer membrane
mRNA surrounded by tiny lipids which help mRNA directly enter into cells
what are immune antigens
active ingredients that directly stimulate the immune response but does not cause the disease
what are the suspension fluids
includes everything inside the vial except active ingredients (includes the chemicals used to inactivate or weaken the virus etc)
what are preservatives and what are some examples of preservatives used in vaccines
used to prevent bacterial and fungal growth, only used in MDV to ensure content and potency remains unchanged
formaldehyde, 2-phenoxyethanol, thimerosal
what are stabilisers and what are some examples of stabilisers used in vaccines
stabilisers are used to keep vaccine stable and maintain its effectiveness during storage, stop chemical reactions from occurring in the vaccine and prevent separation of components or sticking onto vial during transportation and storage which helps to increase shelf life
monosodium glutamate (MSG), gelatin, sorbitol, buffers
what are surfactants and what are some examples of surfactants used in vaccines
amphiphilic molecules with a lipophilic part linked to a hydrophilic part
sorbitan esters, lecithin, mannide oleates, lipopolysaccharides (LPS), glycoside, saponines, DDAB
what are adjuvants
help to induce a more potent immune response
compare between the preservatives (formaldehyde, 2-phenoxyethanol, thimerosal)
formaldehyde: kills or inactivates unwanted germs in a vaccine
2-phenoxyethanol: antimicrobial preservative used in cosmetic and topical formulations, usually used in combination, narrow range of actions, easily eliminated with little toxicity
thimerosal: alternative to benzalkonium chloride or other phenylmercuric preservatives, has bacteriostatic and fungistatic activity, used in parenteral formulations at 0.01% conc, but may trigger hypersensitivity thus slowly phasing out
what happens if you use preservatives with overlapping spectrums
synergistic effect -> can lower dose of bot preservative
what is the consideration for vaccines since it consist of proteins, mRNA etc
temp limit so must ensure it is aseptically produced and used excipients to keep sterile
what are the two types of adjuvants that can be used in vaccines and what are the examples of such adjuvants
vaccine delivery systems and immunostimulatory adjuvants
aluminium salts (phosphates and hydroxides), complete Fruend’s adjuvant, incomplete Fruend’s adjuvant, M59 (for flu vaccine), montanide aka mannide oleate
compare between vaccine delivery systems and immunostimulatory adjuvants
vaccine delivery systems allows nano and microparticles to concentrate and target antigen while immunostimulatory adjuvants are immunopotentiators that activate the immune system directly through cytokines or through pattern recognition receptors (PRRs)
compare between the commonly used adjuvants (aluminium salts, complete and incomplete Fruend’s adjuvant, montanide, MF59)
aluminium salts: commonly used adjuvant, weak effect but slow down rate of release of Ag and increases duration of Ag interaction with immune system
complete Freund’s adjuvant: heat killed mycobacteria -> responsible for stimulating Ab production, has severe side effects
incomplete Freund’s adjuvant: w/o emulsions prepared from non metabolisable oils, very effective but show cutaneous reactivity
MF59: submicron o/w emulsion containing squalene
montanide: family of oil based adjuvants
what is the caution regarding w/o and o/w emulsions
considered toxic and dangerous to use
compare between the stabilisers (monosodium glutamate, gelatin, sorbitol, buffers)
MSG: protects vaccine from heat, light, humidity, acidity during storage
gelatin: protects vaccine from heat during storage
sorbitol: stabilises protein when in solution
buffers: adjust tonicity and maintain osmolarity to keep same as body
what are examples of buffers used as stabilisers
monopotassium phosphate, sodium borate, sodium chloride
where are glycosides and saponines derived from
from quilaja saponaria tree
what are the routes of administration of vaccine
oral, intranasal, subcutaneous, intramuscular
compare between subcutaenous route and intramuscular route
subcutaneous: administered into fatty tissue found below dermis and above muscle tissue
intramuscular: administered into muscle through the skin and subcutaneous tissue
what are jet injectors
needle free devices that pressurise liquid medications, forcing it through a nozzle orifice into a narrow stream capable of penetrating skin to deliver drug or vaccine into intradermal, subcutaneous or intramuscular tissue
how long does vaccine manufacturing take and what are the stages of vaccine manufacturing and what is the shelf life of vaccine
vaccine manufacturing’s lead time can range from several months to three years, shelf life from one to three years
stages: bioprocessing -> formulation, filling, quality control -> finishing and packaging
what are the stages under bioprocessing in vaccine manufacturing
upstream: Ag generated
midstream: removal of cells and cell debris
downstream: Ag separated from impurities and released from substrate through cell lysis if necessary (eg. for mRNA need break virus to release mRNA)
what are the types of Ag produced in the upstream stage of bioprocessing in vaccine manufacturing
- virus generated by primary cell or continuous cell line
- bacteria grown in fermenters
- recombinant protein generated by bacteria
what are the processes involved in the midstream stage of bioprocessing in vaccine manufacturing
- cake/ alluvial filtration
- tangential flow filtration
- centrifugation
what are the processes involved in downstream stage of bioprocessing in vaccine manufacturing
- chromatography
- ultrafiltration
- precipitation
- enzyme digest
compare between the processes in midstream stage of bioprocessing in vaccine manufacturing
cake/alluvial filtration: filter stops flow -> purified version flows through -> over time layers build up on filter -> become more effective -> but can create backpressure -> reach a point where filtration stops completely -> need maintenance
tangential flow filtration: filtration not against flow but along side -> will not clog -> smaller particles go to the side while bigger particles flow along -> not as efficient but depends on area -> use longer pipe to increase filtration area
centrifugation: separation by weight -> bigger particles exit
what is chromatography process in bioprocessing stage of vaccine manufacturing
using HPLC analysis, columns retain certain particles and let others go through
what is precipitation method in bioprocessing stage of vaccine manufacturing
forming reversible complex -> change pH to form precipitate of what you need -> remove precipitate -> reverse reaction -> purify to obtain desired product
what occurs in the formulation stage of vaccine manufacturing
all components that constitute the final vaccine are combined in the formulation process, designed to maximise the stability, efficient distribution and preferred clinical delivery method, may include adjuvant/stabilisers/preservatives
can formulated vaccines be filtered sterilised
no, adjuvants etc are filtered and sterilised separately then aseptically blended before final step
what process occurs in the filling stage of vaccine manufacturing
lyophilisation process:
- dissolve drug and excipients in a suitable solvent, generally water for injection
- sterilise bulk solution by passing it through 0.22microm bacteria retentive filter
- filling into individual sterile containers and partially stoppering it under aseptic conditions
- transport the partially stoppered containers to the lyophiliser and load into chamber under aseptic conditions
- freeze the solution by placing the partially stoppered containers onto cooled shelves in a freeze drying chamber or pre freezing in another chamber
- apply vacuum to the chamber and heat the shelves in order to evaporate the water from frozen state
- complete stoppering of the vials usually by hydraulic or screw rod stoppering mechanisms installed in lyophiliser
what are the parts of the stopper of a vial
stopper flange, aluminium cap, rubber stopper
what is the process of reconstituting a vial with sterile water
- remove stopper flange
- Al cap still on
- pierce rubber stopper with syringe full of sterile water
- shake a little and take out with same syringe
what are the components under quality control stage of vaccine manufacturing
before approval, QC testing, good manufacturing practices (GMP) inspection, pharmacovigilance, additional QC testing by independent labs
what needs to be done before approval (quality control stage)
in depth review of registration file by medicines agencies
what are the components of the registration file to be reviewed (quality control stage)
- all biological materials used in process needs to be screened for potential contaminants
- process, process control, QC tests described
- containers and process equipments evaluated for possible leaching of elements into vaccine
- impurities removal capacities of process needs to be demonstrated
- confirmation of safety of product assessed
- residuals need to be below acceptable limits
- all info above included, reviewed and approved by authorities
what needs to be done in QC stage (quality control stage)
every single batch of vaccines are to be tested by manufacturer according to a predefined set of specifications that has been approved by authorities
testing includes i) general parameters (pH, appearance) ii) identity (correct Ag) iii) potency (correct content of Ag) iv) purity/integrity of Ag v) safety (sterility, endotoxins)
specific tests for potency, purity, integrity depends on type of Ag or vaccine
additional tests may be required if i) potentially toxic compounds used -> test with formaldehyde ii) inactivated vaccines -> test for residual live or bacteria
what are the types of potency tests that can be done during QC stage
- animals testing
positive control (reference) or negative control administered into mice or guinea pigs -> animals then challenged to toxins -> protection induced by vaccine compared to that of reference standard - potency by in vitro immunoassay
using recombinant or subunit Ag
Ag content measured by ELISA
may require additional assays to monitor size, purity, integrity of Ag using SDS-PAGE or SEC-HPLC - potency by live attenuated vaccine
virus titer measured using in vitro cell cultures -> cells are infected with various dilution of vaccines -> cell death quantified -> potency expressed as PFU/ml (number of infective particle units) or TCID50 - potency by polysaccharide vaccine
polysaccharide content, size, purity, degree of adsorption (for vaccines adsorbed onto aluminium)
compare SDS-PAGE and SEC-HPLC
SDS-PAGE: destroy protein using SDS -> identify fragment -> if pattern similar to original protein, can still identify fragment as protein
SEC-HPLC: to identify size and not other surface characteristics of particle done by filtration using different types of columns
what needs to be done for GMP inspection
before and after approval every 2-3 years, verification of compliance with legislation and registration file
what are the components to be complied with for GMP inspection
- compliance with GMP guidelines
- full traceability
- manufacturing and testing done as described in registration file
- quality of raw materials: properly tested as described in registration file
- properly validated and analyticl QC methods
- results within acceptance limits for process controls
