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Flashcards in Vaccines Bacterial and Viral Deck (24)
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1

How is public health implemented in vaccine development? 

  • Making and administering vaccines depends on quantitative data that tells us if its emerging, how many people have it and course of spread 
  • With the two meningococcal infections we dont get cross-protection, this is because the polysaccharide capsule is different hence we need to develop different vaccines 

2

Describe how the MenB vaccine came about

  • There was a vaccine that covered Neisseria meningitidis groups C, A W and Y (conjugated polysaccharide) 
  • In 2015 a group MenB vaccines was developed and administered to new borns, secondary shots were then given at 2 and 4 months and a booster at 12 
  • There was a catch up programme for babies after 1st May 2015 for 
    • However there some issues 
      • More reactogenic
      • Not all serotypes of group B covered (unlike men C)
      • Some cross-protection against men W
      • £75 per dose à needs to be £20 for cost effectiveness
      • 88% efficacy and strain coverage
      • Duration of protection – 10 years (doesn’t provide a lifelong memory)

3

Describe the vaccine that was developed against MenW

  • There was the emergence of a new highly virulent strain W (increasing 2009) 
  • It was decided to vaccine risk groups (young groups): 
    • 14-18 year olds 
    • Older university entrants (aged 19-25) 
  • From spring 2016 it was decided that MenACWY would replace MenC
  • A catch up programme currently offered to year 9 or 10 + catch up year 11s

4

Describe the vaccination schedule for children/young people 

DTaP = (Diptheria, tetanus, Pertussis (Whooping Cough) = toxoid subunit vaccine 

IPV = Inactivated polio virus 

Hib = Haemophilus influenzae type B vaccine

PCV = Streptococcus pneumoniae (pneumonia), Pneumococcal conjugate vaccine (PCV) (subunit polysaccharide) 

 

5

Expand on the vaccination schedule and how it changed

  • HepB was added as there were many children acquiring it during birth from Hep+ mothers 
  • Pneumonia (Streptoccocus pneumoniae), subunit capsular vaccine also given in boosting doses 
  • Rotavirus is live attenuated viral vaccine and it was thought that you would only need to give them once however they need to be given twice 
  • MMR also given twice although it is a live attenuated viral vaccine, as 10% of the people at the age of 1 year miss out and there were still pockets of measels in the community. 

6

Describe Haemophilus Influenza Type B 

  • Capsule polysaccharide linked to conjugate diptheria/tetanus toxoids + outer membrane protein 
  • Given at 2,3,4 months 
  • Causes meningitis 
    • Initially nasopharyngitis 
    • Spreads to an otitis media, sinusitis, bronchitis, pneumonia or sometimes epiglottis (requires tracheotomy) 
    • Can spread into the bloodstream and lead to bacteraemia, spetic arthirits + meningitis (60% of cases) 

7

What type of vaccine is Haemophilus Influenza Type B (Hib) ? 

Capsule polysaccharide linked to conjugate diphtheria/ tetanus toxoids + outer membrane protein

8

Describe diptheria 

  • Caused by corynebacterium diptheriae 
  • Sits in pharynx and undergoes non-invasive multiplication 
    • Produces toxins locally but can cause serious damage at a distance 
      • DT toxin will be released from pharyngeal tissue causing necrosis of tissue (pharyngitis) and neck swelling 
        • Necrotic exudate and pseudomembrane formation 
        • Swelling and oedema in neck can cause respiratory obstruction 
          • Toxins be absorbed by the lymphatics and enter bloodstream where it can have systemic effects on 
            • Heart, kidney and nerves 

 

 

9

How do we vaccinate against diptheria? 

Vaccinated in the dTaP vaccination (diptheria, tetanus and pertussis), toxoid vaccine 

10

Describe tetanus 

  • Caused by clostridium tetani (gram +ve, rods, anaerobic) 
  • Spore forming, soil dwelling organism 
  • Grows in wounds (anaerobic warm environment) and releases toxins that have systemic distribution and an effect on nerves 
    • Paralytic excitation on nerves due to the tetanospasmin toxin cleaving SNARE protein synaptobrevin (preventing release of NT) 

11

What are symptoms of tetanus? 

  • Risus Sardonicus = Grin caused by facial muscle spasm 
  • Opisthotonus = Spasm of all voluntary muscles simultaneously, causes backward arching of head, neck and spine in a locked position 
  • Trismus = Lock jaw

12

How does tetanus cause these symptoms? 

  • Toxin released from tetanus (tetanospasmin is a Zn2+ endopeptidase) 
    • Will cleave synaptobrevin (SNARE PROTEIN)
  • This will block the release of inhibitory neurotransmitters GABA and Glycine = Unopposed continuous excitation = spastic paralysis 
    • The vaccine for this disease generates neutralising toxins; we are able to neutralise them before they get into synapses and they dont have an effect 

13

Describe Whooping Cough (Pertussis) and its vaccine 

  • Whooping cough is a multi-toxin disease
    • Included in the DTaP vaccine (diptheria, tetanus and pertussis (whooping cough)
    • Old vaccine was whole killed vaccine which wasn’t as effective, produced a lot of toxicity and lead to fevers
      • New vaccine is now an acellular vaccine (subunit vaccine)
      • Contains adhesin, pertussis toxoids + outer membrane protein
        • By having these three components the body will produce antibodies against adhesin, surface proteins and the toxin which will block adhesion and neutralise the toxin (through neutralising antibodies)
          • This vaccine is very effective

14

What is the importance of administering the flu vaccine? 

  • The aim of the flu vaccine is to stop vulnerable people from getting the flu
    • These people are at more risk of developing serious illnsses such as heart problems or death should they develop influenza 
      • It is also given to people surrounding them so they dont become carriers and deliver influenza to them
  • . Reduce circulation of the virus 

 

15

What is the problem with the flu virus? 

  • The flu vaccine targets the haemagglutinin surface proteins 
    • However the virus commonly undergoes antigenic shift and antigenic drift 
  • When developing a vaccine, we need to base a vaccine on what will be the most common circulating strain in the following year
  • Different parts of the world have different flu strains circulating  
    • This is an assumption based on notification rates, surveillance rates from hospitals, what components need to be put in place to give us the maximum amount of protection?

16

What is antigenic drift? 

Gradual accumulation of mutations in the haemaglutinin gene = Can cause epidemics 

17

What is antigenic shift? 

Recombination of viruses so they acquire a completely new gene for haemaglutinin that hasnt been in the population = Risk of pandemics 

18

Describe the flu vaccine

  • Orthomyxovirus, influenza type A and B (H3N2 + H1N1+B)

  • .  Surface antigen : purified heamagglutinin + neuraminidase from disrupted virus
    • Trivalent: contains 2 type A and 1 type B corresponding to most likely circulating strains in forthcoming season;
    • 70% protection from vaccine strains for about 1 year
  • Effectiveness depends on 
    • Variable by year/age group
    • Will be effective if the virus is matched to the flu strain present in the population
    • Need to consider antigenic drift and shift
    • Prior exposure; cross-reacting antibodies
    • Vaccine production issues

 

19

What are the two risk groups who are given the streptococcus pneumoniae vaccine? 

  • Given to people over the age of 65-70 and children below the age of 1 

20

What are the two types of streptoccocus pneumoniae vaccines and to whom are they given? 

  1. Pneumococcal Polysaccharide Vaccine (PPV23) 
    • Contains a polysaccharide whose antigens can be recognised by adults but not babies 
  2. Pneumococcal Conjugate Vaccine (PCV-13) 
    • Conjugated to T/D toxoids + OMP as for Hib and MenC

21

Describe the different types of human papilloma virus? 

  • HPV causes genital warts however some serotypes (16,18 specifically) can cause cervical cancer
    • Hence there was a vaccine developed to prevent women from getting cervical cancer as well as protection from genital warts

22

What are the two types of vaccines used for HPV? 

  • Gardasil (used now)
    • Protects us against HPV strains 16, 18, 6 and 11
    • This vaccine is better because it reduces the prevalence of HPV in the community
    • Schedule = Sept 2008 – all 12-13y and 17-18 year old girls
    • 3 doses over 6 months
    • Booster not currently necessary (now 2 doses)
  • Cervarix
    • Protects us against HPV strains 16, 18
  • It is a recombinant capsid L2 protein in Virus-like particles – subunit

23

What vaccines are given to a pregnant mother? 

24

Why do we vaccinate mothers during pregnancy? 

  • We can protect neonates and babies from diseases by vaccinating pregnant mothers 
    • The antibodies are passed onto the neonate and provide short term protection 
      • NO LIVER VACCINES as they can cause damage to the foetus e.g rubella MMR 

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