Lecture 27: Immunisation

Question 1

3 types of protecting us with vaccines?

Answer 1

Protein antigens

• T cell-dependent antibodies

Polysaccharide antigens

• T cell-independent antibodies

Live viral vacccines (attenuated viruses are best or inactivated)

• Antibodies, CD8 cytoxic cells

Conjugate Vaccines

• Cell-wall polysaccharide chemically linked to immunogenic protein

Question 2

Live Vaccine examples?

Answer 2

Modify virus or bacteria in the lab to replicate and produce immunity in the body BUT not illness.

Generally long lasting - many lifelong

Viral = Measels mumps, runella, varicella, oral polio

Bacterial = BCG (tuberculosis), oral typhoid

Reassorted = rotavirus vaccine

(you are still injecting in a live organism so not the best for people who are immunocomromised eg. very small children)

Question 3

“killed” antigen vaccines?

Answer 3

Don’t give lifelong immunity with one dose and so often repeat doses given.

Whole viral = Influenza, injected polio, rabies, Hep A

Whole bacteria = Pertussis, typhoid, cholera

Fractional (component) vaccines = Subunits (HepB, influenza, acellular pertussis)

= toxoids (diptheria, tetanus)

(these are the ones that are preferred as very low risk but you do need more than one injection)

Question 4

Neonatal tetanus and the prevention steps in place?

Answer 4

Accountd for 50% of tetanus deaths in developing world

Gains entry via the umbilical cord to infant incompletely immunised or unimmunised mother - nfant has no passive immunity with no IgG passing through the placenta.

WHO gives all women of child-bearign age in high-risk areas three doses of tetanus toxoid to build immunity and cause increased circulating IgG levels that can pass to offspring.

Question 5

Passive immunisation for tetanus (advantage and disadvantages)?

Answer 5

Human or equine tetanus immunoglobulin provides short lived immunity by neutralising unbound toxins and will shorten the course and lessen the severity of disease in already affected people.

advantages:

• Immediate protection

Disadvantages:

• No long term protection
• Risk of transmission of other disease
• Expensive and not always available
• Serum sickness from injection possible

Question 6

Clinical manifestations of pertussis? Treatment?

Answer 6

Whooping cough (similar sound to that horrible thing Leary does)

• Catarrhal phase (1-2 weeks) - runny nose, conjunctival injection, malaise
• Paroxysmal phase (1-10 weeks) - short expiratory burst of rapid couchs, then inspiratory gasp and high pitched whoop (uncommon in infants and adults)
• Convalescent phase (weeks-months)

Can result in other bacterial infections and rarely encephalopathy, seizures and anpoea.

Eryhtromycin may shorten illness if started early but does little to established illness. Acellular vaccination has high efficacy and requires multiple doese.

Question 7

Poliomyelitis from poliovirus?

Answer 7

Virus destroys LMN resulting in paralysis predominantly affecting children under 5 years. 1 in 200 cases leads to irreversible paralysis and 5-10% die due to respiratory difficulty. Could be eliminated by vaccination.

Question 8

Polio vaccines?

Answer 8

Live oral poliovirus vaccine

• Intestinal immunity of wild-virus circulation
• Rare, vaccine-associated polio disease (1 in 2.4 million)

Inactivated polio vaccine

• 99% effective with 3 doses
• Most countrie have changed from OPV to IPV
• NZ changed to IPV due to lower vaccine associated risk