Vaccines - Bacterial & Viral Flashcards
What is the importance of immunisation schedules
- Keeps booster vaccines up to date to keep protection
- Live attenuated vaccines don’t need boosters as they are generally single-dose
- Increase vaccine coverage
Describe the vaccines for meningitis in the UK
- ## It is classified into different types according to the structure of the polysaccharide coat. Six serogroups responsible for almost all disease in world A, B, C, W-135, X, Y
What are the current MenC vaccine available in the UK
- HiB/MenC combined vaccine given at 1 year. tradename Menitorix. MenC is conjugated bacterial polysaccharide conjugated to tetanus toxoid
- Men ACWY – 14 years. Two available in UK tradenames Menveo and Nimenrix. Menveo consists of polysaccharides from A,C,W-135, Y conjugated to diptheria toxoid.
Why is it hard to develop a MenB vaccine
- Very difficult to develop because polysaccharides are too similar to that on some human cell
- A vaccine was developed in 2015
- Maybe not cost effect for mass vaccination
Describe the Hib vaccine
Type b capsule polysaccharide linked to conjugate:-
either diphtheria or tetanus toxoids or meningococcal outer membrane proteins
Describe the effects of diphtheria pathogen which is vaccinated by DTP
- Inhibits protein synthesis in eukaryotes
- Pharynx, larynx, nose - non-invasive multiplication
- Toxin produced locally but acts at a distance
- absorbed by lymphatics - systemic effects
- damages heart, kidney, nerves, adrenals
- kills epithelial cells and polymorphs
- gelatinous exudate ulcer - necrotic exudate - Pseudomembrane
How does the vaccine work to prevent diphtheria
- Diphtheria toxin treated to make the toxoid which is not toxic but is immunogenic
- Combined with aluminium salts adjuvant
- Given as combined vaccine DTaP or dTaP (D = higher amount of toxoid)
Describe the effects of tetanus pathogen which is vaccinated by DTP
- Caused by Clostridium tetani which is gram +ve rods, that exist within soil
- Tetanus toxin is a neurotoxin that inhibits the release of neurotransmitters (GABA, glycine) from inhibitory interneurons, which interact with motor neurones, resulting in violent spastic paralysis.
How does the vaccine work to prevent tetanus
- Tetanus toxin is treated with formaldehyde to convert it into a toxoid, loss of toxicity but not immunogenicity
- Combined with aluminium salt adjuvant
Describe the effects of pertussis pathogen which is vaccinated by DTP
- Severe cough lasting weeks often with a ‘whoop’ noise. Cough can last for weeks. WC can result in death especially in newborns
- Bacterium adheres to ciliated epithelial cells in upper respiratory tract and multiplies. In infants may descend to lungs
- Secretes pertussis toxin which is a virulence factor in pathogenesis of the disease and causes many of systemic symptoms including profound leukocytosis
How does the vaccine work to prevent pertussis
- Old vaccine: Whole cell killed vaccine - reactogenic (fever, headaches, redness), concerns over efficacy in some countries and lingering concerns over link with brain damage
The new vaccine is an acellular vaccine which contains pertussis toxoid - Blocks adhesion and neutralises toxin
What are the main aims of the Influenza programme
- To protect those who are most at risk of serious illness or death should they develop influenza
- To reduce the circulation of the virus
Who are vaccinated against influenza
- all those aged 65 years or over
- all those aged 6 months or over in a clinical risk group
- those living in long-stay residential facilities
- those who care for elderly or disabled persons
- household contacts of immunocompromised individuals
- those working within health and social care settings
- pregnant women
What is influenza
- RNA virus with 3 types and multiple serotypes
- Surface glycoproteins Haemagglutinin
(H/HA) and Neuraminidase (N/NA) - Seasonal flu – yearly, up to half a million
deaths
What Influenza types mostly cause disease
Types A and B
