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vaccines Flashcards

1
Q

what is the difference between active and passive immunisation

A

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

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2
Q

what are the types and levels of protection obtained through vaccination

A

individual protection, herd immunity, global protection, indefinitely shelter future generations from harm

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3
Q

what are the types of vaccines

A

inactivated
live, attenuated
subunit, recombinant, polysaccharide and conjugate
toxoid
viral vector
mRNA

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4
Q

what are the basic components in a vaccine

A

immune antigens, suspension fluids, stabilisers, preservatives, emulsifiers/ surfactants, adjuvants

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5
Q

what are the requirements of vaccine

A
  1. 100% effective in all age groups
  2. should provide long term protection after a single application, for a lifetime if possible
  3. should not have side effects
  4. should be stable in different conditions (heat, light, transport)
  5. should be easily accessible and inexpensive
  6. should protect against more than one diseases at the same time, should be able to simulate both systemic and mucosal immunity
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6
Q

what do vaccines contain and how does it affect the stability of vaccines

A

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

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7
Q

what is a cold chain

A

temperature controlled supply chain that includes all vaccine related equipment and procedures

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8
Q

what are the characteristics of a cold chain

A

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

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9
Q

what are inactivated vaccines and what kind of reponse do they produce

A

contain bacteria or viruses that has been inactivated by heat or chemically

produces a weak immune response and requires repeated doses

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10
Q

what are examples of inactivated vaccines

A

polio, hep A, flu shot, rabies

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11
Q

what is the manufacturing process of inactivated vaccines

A

virus -> live cells -> inactivated by chemicals -> purification and impurity removal -> vaccine stock bulk -> filling and packaging

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12
Q

what are live attenuated vaccines and what kind of response do they produce

A

maintains antigenicity but loses pathogenicity, similar to natural infection

strong and long lasting immune response

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13
Q

what are examples of live attenuated vaccines

A

MMR, rotavirus, chicken pox, small pox, yellow fever

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14
Q

what are the disadvantages of live attenuated vaccines

A

not suitable for immunocompromised and transplant receivers, need to be refrigerated, can become live again and cause host with the vaccine to fall sick

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15
Q

what is the manufacturing process of live attenuated vaccines

A

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

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16
Q

what are subunit, recombinant, polysaccharide and conjugate vaccines

A

contains a specific part of the pathogen which can be protein, peptide or polysaccharide

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17
Q

what is the difference between recombinant and conjugate vaccine

A

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

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18
Q

what are examples of recombinant and conjugate vaccines

A

shingles (recombinant), hep B (recombinant), haemophillus influenzae (conjugate), pertussis aka whopping cough

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19
Q

what are toxoid vaccines and how does it work

A

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

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20
Q

what are the disadvantages of toxoid vaccines

A
  1. need boosters as immune response not high
  2. need adjuvant to increase immune response
  3. difficult to manufacture as want to inactivate toxin but not by too much such that the structure is disrupted and cannot provide adequate immunity
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21
Q

what is the manufacturing process of toxoid vaccines

A

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

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22
Q

what are viral vector vaccines

A

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

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23
Q

what is the manufacturing process of viral vector vaccines

A

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

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24
Q

what are mRNA vaccines

A

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

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25
Q

what are immune antigens

A

active ingredients that directly stimulate the immune response but does not cause the disease

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26
Q

what are the suspension fluids

A

includes everything inside the vial except active ingredients (includes the chemicals used to inactivate or weaken the virus etc)

27
Q

what are preservatives and what are some examples of preservatives used in vaccines

A

used to prevent bacterial and fungal growth, only used in MDV to ensure content and potency remains unchanged

formaldehyde, 2-phenoxyethanol, thimerosal

28
Q

what are stabilisers and what are some examples of stabilisers used in vaccines

A

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

29
Q

what are surfactants and what are some examples of surfactants used in vaccines

A

amphiphilic molecules with a lipophilic part linked to a hydrophilic part

sorbitan esters, lecithin, mannide oleates, lipopolysaccharides (LPS), glycoside, saponines, DDAB

30
Q

what are adjuvants

A

help to induce a more potent immune response

31
Q

compare between the preservatives (formaldehyde, 2-phenoxyethanol, thimerosal)

A

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

32
Q

what happens if you use preservatives with overlapping spectrums

A

synergistic effect -> can lower dose of bot preservative

33
Q

what is the consideration for vaccines since it consist of proteins, mRNA etc

A

temp limit so must ensure it is aseptically produced and used excipients to keep sterile

34
Q

what are the two types of adjuvants that can be used in vaccines and what are the examples of such adjuvants

A

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

35
Q

compare between vaccine delivery systems and immunostimulatory adjuvants

A

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)

36
Q

compare between the commonly used adjuvants (aluminium salts, complete and incomplete Fruend’s adjuvant, montanide, MF59)

A

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

36
Q

what is the caution regarding w/o and o/w emulsions

A

considered toxic and dangerous to use

37
Q

compare between the stabilisers (monosodium glutamate, gelatin, sorbitol, buffers)

A

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

38
Q

what are examples of buffers used as stabilisers

A

monopotassium phosphate, sodium borate, sodium chloride

39
Q

where are glycosides and saponines derived from

A

from quilaja saponaria tree

40
Q

what are the routes of administration of vaccine

A

oral, intranasal, subcutaneous, intramuscular

41
Q

compare between subcutaenous route and intramuscular route

A

subcutaneous: administered into fatty tissue found below dermis and above muscle tissue
intramuscular: administered into muscle through the skin and subcutaneous tissue

42
Q

what are jet injectors

A

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

43
Q

how long does vaccine manufacturing take and what are the stages of vaccine manufacturing and what is the shelf life of vaccine

A

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

44
Q

what are the stages under bioprocessing in vaccine manufacturing

A

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)

45
Q

what are the types of Ag produced in the upstream stage of bioprocessing in vaccine manufacturing

A
  1. virus generated by primary cell or continuous cell line
  2. bacteria grown in fermenters
  3. recombinant protein generated by bacteria
46
Q

what are the processes involved in the midstream stage of bioprocessing in vaccine manufacturing

A
  1. cake/ alluvial filtration
  2. tangential flow filtration
  3. centrifugation
47
Q

what are the processes involved in downstream stage of bioprocessing in vaccine manufacturing

A
  1. chromatography
  2. ultrafiltration
  3. precipitation
  4. enzyme digest
48
Q

compare between the processes in midstream stage of bioprocessing in vaccine manufacturing

A

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

49
Q

what is chromatography process in bioprocessing stage of vaccine manufacturing

A

using HPLC analysis, columns retain certain particles and let others go through

50
Q

what is precipitation method in bioprocessing stage of vaccine manufacturing

A

forming reversible complex -> change pH to form precipitate of what you need -> remove precipitate -> reverse reaction -> purify to obtain desired product

51
Q

what occurs in the formulation stage of vaccine manufacturing

A

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

52
Q

can formulated vaccines be filtered sterilised

A

no, adjuvants etc are filtered and sterilised separately then aseptically blended before final step

53
Q

what process occurs in the filling stage of vaccine manufacturing

A

lyophilisation process:

  1. dissolve drug and excipients in a suitable solvent, generally water for injection
  2. sterilise bulk solution by passing it through 0.22microm bacteria retentive filter
  3. filling into individual sterile containers and partially stoppering it under aseptic conditions
  4. transport the partially stoppered containers to the lyophiliser and load into chamber under aseptic conditions
  5. freeze the solution by placing the partially stoppered containers onto cooled shelves in a freeze drying chamber or pre freezing in another chamber
  6. apply vacuum to the chamber and heat the shelves in order to evaporate the water from frozen state
  7. complete stoppering of the vials usually by hydraulic or screw rod stoppering mechanisms installed in lyophiliser
54
Q

what are the parts of the stopper of a vial

A

stopper flange, aluminium cap, rubber stopper

55
Q

what is the process of reconstituting a vial with sterile water

A
  1. remove stopper flange
  2. Al cap still on
  3. pierce rubber stopper with syringe full of sterile water
  4. shake a little and take out with same syringe
56
Q

what are the components under quality control stage of vaccine manufacturing

A

before approval, QC testing, good manufacturing practices (GMP) inspection, pharmacovigilance, additional QC testing by independent labs

57
Q

what needs to be done before approval (quality control stage)

A

in depth review of registration file by medicines agencies

58
Q

what are the components of the registration file to be reviewed (quality control stage)

A
  1. all biological materials used in process needs to be screened for potential contaminants
  2. process, process control, QC tests described
  3. containers and process equipments evaluated for possible leaching of elements into vaccine
  4. impurities removal capacities of process needs to be demonstrated
  5. confirmation of safety of product assessed
  6. residuals need to be below acceptable limits
  7. all info above included, reviewed and approved by authorities
59
Q

what needs to be done in QC stage (quality control stage)

A

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

60
Q

what are the types of potency tests that can be done during QC stage

A
  1. 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
  2. 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
  3. 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
  4. potency by polysaccharide vaccine
    polysaccharide content, size, purity, degree of adsorption (for vaccines adsorbed onto aluminium)
61
Q

compare SDS-PAGE and SEC-HPLC

A

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

62
Q

what needs to be done for GMP inspection

A

before and after approval every 2-3 years, verification of compliance with legislation and registration file

63
Q

what are the components to be complied with for GMP inspection

A
  1. compliance with GMP guidelines
  2. full traceability
  3. manufacturing and testing done as described in registration file
  4. quality of raw materials: properly tested as described in registration file
  5. properly validated and analyticl QC methods
  6. results within acceptance limits for process controls

pr3151 (12 decks)

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