Vaccines Bacterial and Viral Flashcards
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
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)
- However there some issues
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
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)
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.
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)
What type of vaccine is Haemophilus Influenza Type B (Hib) ?
Capsule polysaccharide linked to conjugate diphtheria/ tetanus toxoids + outer membrane protein
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
- Toxins be absorbed by the lymphatics and enter bloodstream where it can have systemic effects on
- DT toxin will be released from pharyngeal tissue causing necrosis of tissue (pharyngitis) and neck swelling
-
Produces toxins locally but can cause serious damage at a distance
How do we vaccinate against diptheria?
Vaccinated in the dTaP vaccination (diptheria, tetanus and pertussis), toxoid vaccine
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)
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
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
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
- 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)
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
- These people are at more risk of developing serious illnsses such as heart problems or death should they develop influenza
- . Reduce circulation of the virus
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?
What is antigenic drift?
Gradual accumulation of mutations in the haemaglutinin gene = Can cause epidemics
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
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
What vaccines are given to a pregnant mother?
