The Case Of The Vaccine Refuser + The Case Of The Misunderstood Disease Flashcards
(93 cards)
The principle of vaccination are often …
misunderstood
The reduction in the number of cases of infectious diseases is testament to the incredible success of vaccination as a global … strategy.
The reduction in the number of cases of infectious diseases is testament to the incredible success of vaccination as a global preventative strategy.
What is a vaccine?
Usually, a vaccine is an agent causing a “pretend” infection that the body will fight
What are the advantages of vaccines? (4)
Can be administered at will and as required before an infection is contracted
Much lower risk and fare fewer side effects than the real infection
They prevent the real infection from occurring or reduce its severity and duration
Can be tailored to different target groups
Important requirements for vaccines
Must be safe to use and not cause the disease they aim to prevent
Must have minimal side effects
Must be long acting
Must be easy to store and transport
Must be cheap as possible
Basic types of vaccines
Active - causing the organisms to mount an immune response as if a real infection had taken place
Passive - providing the organisms with a ‘prefabricated’ immune response
Active and passive immunisation in history
Active vaccination practices in early 1700s in china - small amounts of pus from patients with small pox were used to inoculate others to prevent them from getting the disease
Edward Jenner and Small Pox
In the UK, Edward Jenner is credited with the foundation of modern vaccinology - used pus from a milk maid infected with cow pox to ‘vaccinate’ an orphaned boy - potentially lethal but he went ahead anyway and luckily the boy survived
Emil von Behring and passive immunisation - Diphteria
Horse anti-serum is used as a basis for preparing a medicine used for treating patients with diphteria, called diphteria anti-toxin
Horses injected with corynebacterium diphteriae toxin
Antitoxin prepared for human use from the horse serum
Passive immunisation - Horse serum for diphteria
Disadvantage - horse protein induces anti-antibodies in the patient, which beginning about a week to 10 days after inoculation will form complexes with the horse immunoglobin and inactivate it
These complexes can be deposited and cause secondary immune complex disease
Passive immunisation - Horse serum for diphteria (2)
Horse antitoxin is more rapidly eliminated than human antitoxin - half life of human IgG is about 20 days but than of horse antitoxin less than 5 days
Repeat administration of horse antiserum can cause severe ….
anaphylactic shock - today horse antiserum is still in use but will hopefully soon be replaced by human IgG produced in bio-reactors
Basic types: Live Vaccines
Also called ‘attentuated’; contain agents that have been weakened, but not killed
Attenuated agents cannot normally cause disease in healthy people, but can still replicate to produce a strong immune response
Basic types : recombinant and synthetic vaccines
DNA/RNA vaccines - various infections, cancer
protein/virus like particle - Hep B, HPV
Subunit vaccines - Hep B, TB (experimental stage)
Subunit/conjugate - HIB (polysaccharide plus protein)
Toxoid - Tetanus, Diphteria
Common passive vaccinations in practice
Hep B hyperimmune serum - post-exposure
Tetanus hyperimmune serum - post-exposure
Rabies hyperimmune serum - post-exposure
Anti-venoms, anti-toxins, etc - post-exposure
Hep A hyperimmune serum used to be given as exposure prophylaxis - now, an active, pre-exposure vaccine is available
VSV hyperimmune globulin is an effective prophylaxis for babies and mothers who develop varicella in a 1 week period before or after delivery
When do routine childhood immunisations start in the UK?
8 weeks old - schedule is updated to reflect changing needs and new vaccine developments
Live Vaccines should not be given to individuals who …
have a compromised immune system, because they could develop the disease the vaccine is designed to prevent
COVID-19 and vaccine development
Actual immune correlates or protection are still not fully understood, antibodies to the SARS-CoV-2 spike and nucleocapsid proteins appear to correlate with protection to a large extent
Interestingly, human coronaviruses causing the common cold seem to leave little immunity, however cross-reactivity appears to contribute to protection against covid in large parts of the population
A passive vaccine against COVID-19?
The SARS-CoV-2 spike protein can bind to ACE-2 and NRP-1 both of which are located at the cell surface
Regeneron Pharmaceuticals have developed an apparently effective antibody cocktail from recovered patients and humanised mice containing antibodies that recognise different receptor binding domain in a non-competitive fashion and abrogate binding
B-cells and antibodies: Therapeutics
Therapeutic antibodies recognising the spike protein are administered to individuals with COVID-19 to avoid serious disease courses
Treatment with REGN-COV2 resulted in a statistically significant reduction in the time-weighted average daily change from baseline in viral load from day 1 through day 7
Can be given to household members for protection - reduced the rate of symptomatic infection by 81% day 0 and 29
RNA-vaccines
Intracellular mRNA stability is achieved by:
a specially modified nucleotide positioned at the 5’ end (Cap)
A poly (A) tail (length)
The composition and structure of the 3’ untranslated regions (3’UTR)
good things about vaccines? (3)
prevent or reduce severity of infections can be tailored to different groups can be given in advance of an infection
requirements for effective vaccine (5)
safe, doesn’t cause disease minimal side effects long lasting easy to store/transport cost effective
patient’s own immune system is activated and the protection is usually life-long
patient’s own immune system is activated and the protection is usually life-long = active vaccination
