Lecture 27: Immunisation Flashcards
What are the benefits of vaccination to the public and to the individual?
For individual,
- immunity to infection
For population:
- Reduced transmission of infection
- Reduced disease in vaccinated AND unvaccinated people (herd immunity)
What are the different types of Vaccines?
- Protein antigens
- using T cell-dependent antibodies
- Polysaccharide antigens
- using T cell-independent antibodies
- Live viral vaccines
- using antibodies, CD8 cytotoxic cells
What are the 2 classifications of vaccines?
Live attenuated vaccines include:
- Live viruses or live bacteria
Inactivated vaccines include:
- Whole viruses or bacteria, or fractions but cannot multiply
-
Protein-based vaccines
- are toxoids (inactivated bacterial toxin), subunit or subvirion
-
Polysaccharide-based vaccines
- are pure cell-wall polysaccharide from bacteria
-
Conjugate polysaccharide vaccines
- are cell-wall polysaccharide chemically linked to a protein
- Taken some antigens from polysaccharides and attached to immunogenic protein to increase response (compared to polysaccharide-based vaccines)
- are cell-wall polysaccharide chemically linked to a protein
Describe Live Vaccines
Live vaccines are modified virus or bacteria in lab.
Replicate and produce immunity but _not illnes_s.
Generally l_ifelong immunity._
- Viral: such as measles mumps, rubella, varicella, oral polio vaccine
- Bacterial: such as BCG (tuberculosis), oral typhoid vaccine
- Reassorted such as rotavirus vaccine (Rotateq)
Can cause problems in immunocompromised people
(infectious cycle)
Describe Inactivated Vaccines
Inactivated vaccines can be “killed” antigen vaccines.
Not lifelong immunity with one dose. Repeat immunisation necessary.
- Whole viral
- such as influenza, injected polio, rabies, and hep A
- Whole bacterial
- such as pertussis, typhoid, cholera
Inactivated vaccines can also be “fractional” vaccines (preferred)
- Subunits (hep B, influenza, acellular pertussis)
- Toxoids (diphtheria, tetanus)
(no infectious cycle, stimulation of the immune system isn’t that great so not a lot of memory or response. Therefore you need a few doses)
Name some Live Vaccines
- Viral such as
- measles mumps,
- rubella,
- varicella,
- oral polio vaccine
- Bacterial such as
- BCG (tuberculosis),
- oral typhoid vaccine
- Reassorted such as
- rotavirus vaccine (Rotateq)
Name some Inactivated Vaccines
- Whole viral such as
- influenza,
- injected polio,
- rabies, and
- hep A
- Whole bacterial such as
- pertussis,
- typhoid,
- cholera
Inactivated vaccines can also be “fractional” vaccines (preferred)
- Subunits
- (hep B, influenza, acellular pertussis)
- Toxoids
- (diphtheria, tetanus)
Describe Recombinant Vaccines
Hepatitis B vaccines are segment of hepatitis B virus gene into yeast expression system
Live attenuated influenza vaccine (LAIV) are engineered to replicate effectively in mucosa of nasopharynx but not in lungs
(but for the future- not really used now)
Describe the vaccinations that are given to children (what they are and when they are given)
D T aP IPV HepB HiB (Infanrix-hexa) are 6 vaccinations in one injection, including diphtheria, tetanus, acellular pertussis, inactivated polio, haemophilus influenza type B, hepatitis B.
- All component antigen vaccines (HepB are recombinant surface antigen, HiB are protein conjugated polysaccharide)
- Given at 6 weeks, 3 months, 5 months, 4 years
M M R are measles, mumps, rubella
- All live virus vaccines
- Given at 15 months (and 4 years)
- Later because they are live and we aren’t sure about the immunocompetence of the individual
D T aP IPV HepB HiB (Infanrix-hexa) are 6 vaccinations in one injection, including …..
D T aP IPV HepB HiB (Infanrix-hexa) are 6 vaccinations in one injection, including
- diphtheria,
- tetanus,
- acellular pertussis,
- inactivated polio,
- haemophilus influenza type B,
- hepatitis B.
Describe the Tetanus Immunisation
Clostridium tetania are anaerobic, spore-forming, Gram-positive bacillus, penicillin-sensitive
- Spores everywhere, particularly manure/soil
- Easily introduced at time of injury, especially deep penetrating dirty wounds
Toxin symptoms starts ~10 days after exposure of a wound to dirt/soil.
Symptoms
- Muscular rigidity caused by tetanospasmin toxin.
- Clinical features of arching of back (opisthtonus), f_acial grimace (_risus sardonicus), ‘lock jaw’
Tetanus is uncommon in developed world due to universal immunisation (34 cases 2000-2010 in NZ). Major problem in the developing world (≈ 300,000 deaths per year). Most at risk are those over the age of 60, where immunity has waned.
What are the symptoms and clinical features of Tetanus?
Muscular rigidity caused by tetanospasmin toxin.
Clinical features of
- _arching of back (_opisthtonus),
- facial grimace (risus sardonicus), ‘lock jaw’
Describe the Neonatal Tetanus
Neonatal tetanus accounts for 50% of tetanus deaths in developing world. Mortality rate >90%
-
Entry via umbilicus to infant of incompletely or _unimmunised mothe_r (developing world)
- Antibodies aren’t passed onto the babies
- Infant has no “passive immunity”, i.e. no IgG passed through from mother
- Failure of aseptic technique during birth
WHO aim is elimination of neonatal tetanus. Plan is to give all women of child-bearing age in high-risk areas three doses of tetanus toxoid.
If someone who hasn’t been immunised is infected, what can you do? (for Tetanus)
It provide passive immunisation via human or equine tetanus immunoglobulin (TIG)
- Acquire immunity by transfer of serum (Ig) from a donor to a non-immune person
- Neutralises unbound toxin
- Shortens the course, lessens the severity of disease, improves survival
Required if dirty wound and no previous tetanus immunisations
What are the advantages and disadvantages of Passive Immunisation?
Passive immunisation has advantages of
- immediate protection
However, disadvantages
- no long-term protection
- Risk of transmission of other disease from donor
- Expensive and not always easily available (esp in developing countries)
- Serum sickness (side effects) from injection of another person’s or animal’s serum
Describe the organism that cuases Pertussis
Pertussis (Whooping Cough)
Bordetella pertussis is Gram-negative bacilli (cocci-bacillus). It is among 10 most common causes of death from an infectious disease. It is a leading cause of vaccine-preventable deaths.
- ~ 50 million cases causing 350,000 deaths annually, 90% in 3rd world
- Highest mortality in first year of life
- Highly contagious, household spread up to 90%
What are the clinical manifestation sof Pertussis?
Clinical Manifestations
Pertussis is deposited in respiratory tract by aerosol droplets produced by the cough (very infectious).
Clinical manifestations include:
- Catarrhal phase (1 to 2 weeks) includes runny nose, conjunctival injection, malaise
- Paroxysmal phase (1 to 10 weeks) includes short expiratory burst of rapid coughs, then inspiratory gasp and high-pitched whoop (uncommon in infants and adults)
- Convalescent phase (weeks to months)
What are some complications of Pertussis?
Complications
- Secondary bacterial infections such as pneumonia
- Encephalopathy, seizures, apnoea
How do you treat Pertussis?
Treatment: Antibiotics?
Erythromycin (macrolide antibiotic) may shorten illness if started early (during first few weeks of illness). It decrease infectivity but do little in established illness.
Describe the features of Pertussis Vaccines
Pertussis Vaccines
Pertussis vaccines include:
- Whole cell vaccine (old vaccine) killed whole cell vaccines (efficacy ≈80%). Introduced in NZ 1945. Major limitation of local and systemic reactions.
- Acellular vaccine contains a number of virulence factors (efficacy ≈85%). It is used since August 2000. It is a 3-dose primary schedule and 2 booster doses.
Infanrix HEXA (DTaP IPV HepB HiB) include diptheria, tetanus, pertussis, polio, hepatitis B, Haemophilus influenza type B.
- Nearly 90% coverage by 2 years, but only 50% get 3rd dose at 5 months (‘timeliness’)
- Immunisation gives 80% protection to 6 years, immunity wanes 5 to 10 years
- Booster pertussis dose at age 11 years on schedule since 2008
Vaccination has changed pertussis epidemiology.
How has pertussis epidemiology changed?
Vaccination has changed pertussis epidemiology.
Recommended for Pertussis Vaccine
- Parents and other adults living in the households with young children
- Family members (particularly parents) source of infection in > 50% of cases
- Adults working with children specifically teachers or childcare employees
- Health care workers, particularly those working with newborns
Describe Poliomyelitis
- What does it cause?
- Who does it mostly effect?
Poliomyelitis from Poliovirus
Poliovirus destroys lower motor neurons resulting in paralysis.
Predominantly affects children under 5.
- 1/200 leads to irreversible paralysis (legs usually), 5-10% die due to respiratory difficulty.
- By 2008, polio endemic only in 4 countries Afghanistan, India, Nigeria and Pakistan. Could be eliminated by vaccination
Describe Polio Vaccines
Polio vaccines can be live oral poliovirus vaccine (OPV)
- It is used where polio endemic Intestinal immunity, controls of wild-virus circulation
- Rare, vaccine-associated paralytic polio disease VAPP (1 case for every 2.4 million doses)
Polio vaccines can also be inactivated polio vaccine (IPV)
- It has 99% effective with three-dose course
- Just the antigens of the poliovirus
- Most countries have changed from using OPV to IPV (NZ changed to IPV in 2002)
