Vaccines: bacterial and viral

Question 1

What do we know about Haemophilus influenza type B? how effective is the vaccine and what is it made up of?

Answer 1

Paediatric disease - usually 6 mo - 3 yrs 1/600
Initially, a nasopharyngitis (often starting with viral infection)
spreads to an otitis media,
sinusitis, bronchitis, pneumonia or
sometimes epiglottitis (requiring a
tracheotomy):- croup

Spreads : bacteraemia,
septic arthritis,
meningitis (60% cases)

Neurological disorders (33%) or
death (5%) if not vigorously treated
Vaccine effective: (99% cases are type b)

type b - capsule polysaccharide linked to conjugate:-
diphtheria/tetanus toxoids + outer membrane proteins

Question 2

What do we know about diphtheria?

Answer 2

Pharynx - non-invasive multiplication

Toxin produced locally but acts at a distance
- absorbed by lymphatics – systemic effects
damages heart, kidney, nerves, adrenals

• the bacteria kills epithelial cells and polymorphs
  gelatinous exudate
• ulcer - necrotic exudate - Pseudomembrane
• local inflammation ,swelling, lymph nodes - Bull Neck
• Respiratory obstruction
  Diphtheria is a toxin-mediated disease so the vaccine we use targets the toxin of the bacteria

Question 3

Why is a new vaccine needed every year for the flu/influenza?

Answer 3

Influenza viruses are always changing- influenza genes DRIFT to create new viruses.

Around the RNA are different proteins called haemagglutinin(HA) and neuraminidase(NA).
There are 16 subtypes of HA and 9 subtypes of NA.

Question 4

What is pneumococcal vaccine?

Answer 4

1. Pneumococcal Polysaccharide Vaccine PPV23
   The 23-valent pneumococcal polysaccharide vaccine (PPV) for at risk adults and children over the age of 2

Children under 2 can’t make a long-lasting protective immune response to polysaccharide vaccines.

These 23 types of bacteria cause about 96% of all pneumococcal disease cases in the UK

to target the fact that children under 2 could not gain long-lasting protection from the Pneumococcal Polysaccharide Vaccine PPV23, another vaccine was made that is conjugated:

2. Pneumococcal Conjugate Vaccine PCV-13V
   Polysaccharides from 13 most common capsule types
   Conjugated to T/D toxoids + OMP as for Hib and MenC

Estimated that the capsular types in the vaccine cause
~66% of all pneumococcal disease cases and
82% of pneumococcal disease in under five year olds