Vaccines Flashcards
How does a vaccine work?
*antigens, on the surface of the weakened or dead bacteria or viruses introduced into blood
*antigen presenting cells (APC’s) capture and ingest antigen and express on their surface
*APC’s move to cluster of immune cells. Activate T cells, trigger killer T cel,s and maturation of B Cells
*naive killer T cells become mature killer T cells specific to the antigen,
*if vaccine live- t killer cells destroy cells
*now have memory killer T cells
*b cells produce antibodies binding to antigens, marking for killer T cells
*memory b cells produced
What are characteristics of an ideal vaccine?
*produce immune protection without causing disease
*generate long lasting immunity
*interrupt infection spread
What types of vaccines are there ?
*live weakened
*inactivated
*subunit- conjugate
*nucleic acid vaccines- RNA
What are advantages of live weakened vaccines?
*most potent vaccine - mimic real infection
*strong immune response
*long term immunity after one or two doses
What are disadvantages of live weakened vaccines?
*potential to revert to infectious form
*poor stability- strict storage and transport conditions
*not given to immunocomp
What are examples of live weakened vaccines?
*shingles
*measels
What are examples of inactive vaccines?
*polio
*influenza
What are advantages of inactivated vaccines?
*safer than live weakened
*more stable- easier to store
What are disadvantages of inactivated vaccines?
*if not treated well enough, can leave live infectious agents in vaccine
*requires booster
What are advantages of subunit vaccines?
*only part of antigen used- not whole pathogen so saved
*can be given to immunocomp
What are disadvantages of subunit vaccines?
*complicated to manufacture
*local side effects more common ie pain at injection site
What is an example of a conjugate subunit vaccine?
Pneumococcal vax
What are nucleic acid vaccines?
*do not supply antigen
*supply rna of antigen to develop immunity
What are advantages of nucleic acid vaccines?
*safer- don’t contain whole pathogen
*easy to make
What are disadvantages of nucleic acid vaccines?
*ultra low storage <70°C
*boosters
How does the Covid 19 RNA vaccine work?
*mRNA injected
*mRNA of spike protein of SARS-CoV-2 (antigen)
*mRNA taken up by host cell, which translates genetic info into producing spike proteins
*stimulates immune system to produce antibodies and activate T cells
What is a viral vectored vaccine?
*vector carries genetic sequence for antigen (or spike protein)
*stimulates immune system, make antibodies, activate T cells
(AstraZeneca vax)
How does the viral vector vaccine by AstraZeneca work for Covid?
*non replicating viral vector vaccine
*used part of weakened adenovirus as Carrier to deliver genetic sequence for SARS-CoV-2 virus spike proteins
*modified adenovirus binds to host cells, delivers mRNA for spike protein
*stimulates immune system
What ingredients in a vaccine provide immunity?
*antigen- active component or RNA of it- generate immune response
*adjuvant- improves immune response to vaccine- aluminium phosphate
What ingredients in a vaccine keep them safe and long lasting?
*preservatives- prevent contamination once open- 2-phenoxyethanol
*stabilisers- prevent chemical reactions occurring within vaccine- keep vax components sticking to vial- sugars
*surfactants- keep all ingredients blended together- prevent settling and clumping- polysorbate 80
What two extra ingredients are in vaccines?
*residuals- tiny amount of substance used during manufacture- yeast, antibiotics
*diluent- dilute to correct conc- sterile water
Apart from the API in a vaccine, what is the other main ingredient?
Water
What phases are there in vaccine clinical trials?
*preclinical- animal testing- if triggers immune response, tested in humans
*phase 1- small no of HEALTHY individuals-assess safety and dose
*phase 2- several hundred- volunteers with same characteristics ie age and sex- asses safety, dose and confirms immune response
*phase 3-thousands of volunteers- determines efficacy, assess safety in large group
*phase 4- ongoing studies
At what temperatures are vaccines stored?
*2-8°C
*-20°C
*-70°C
Term- cold chain
What is the purpose of cold chain in vaccines?
*maintain vaccine product integrity from time of manufacture to administration
*storage outside recommended leads to: formulation degradation, product contamination, loss of potency, substandard immune response
What muscle are vaccines administered into usually?
Deltoid (upper arm)
*if unsuitable, vastus lateralis (middle thigh)
How is a vaccine administered IM?
*identify correct site
*stretch skin at site
*insert at 90° angle
*depress plunger
*gently remove needle
*apply light pressure if bleeds
What are the benefits of administering vaccine into muscles?
*better immune response- muscle contains cells to initiate immune response
*less likely to cause local reaction
What are challenges in vaccinations?
*anti vax movement
*social media
Myth: contain mercury which is dangerous- very few contain thiomersal- no evidence risk to health
