principles of immunisation

Question 1

Describe the principles of active and passive immunisation.

Answer 1

Active: infection or vaccination transfers antigenic material to organisms which stimulates an immune response which generates memory cells and specificity
Passive: transfer of serum of antibodies which allows temporary relief from antigenic material. Can be natural-placental transfer- or artificial: immunoglobulin transfer. Does not produce memory cell but does allow specificity

Question 2

Describe the types of vaccine available for active immunisation

Answer 2

• Killed whole organism: Virus is killed by heating- will require boosts
• Attenuated whole organism: virus is extracted from human cells and cultured on plate with other human cells. It is then injected into monkey cells where it becomes attenuated. This virus can then be used in vaccinations
• Sub-unit: Uses recombinant proteins. It is easy to standardise but needs to be combined with an adjuvant in order to be immunologically effective. e.g. HPV
• Toxoid: A toxin treated with formalin- only effect against toxin- not entire antigen
• Conjugate: carbohydrate antigen capsule. Not very effective unless used in conjunction with protein.

Question 3

Define what is meant by the term vaccination

Answer 3

Administration of antigenic material which triggers the immune system to trigger a response which will develop adaptive immunity against a pathogen

Question 4

Describe the contra-indications to vaccination

Answer 4

Short-term: -Attenuated viruses cannot be administered during pregnancy
-Febrile illness
Long-term:
-allergy
-Immunocompromised patients cannot be vaccinated.

Question 5

Describe how an immune response occurs

Answer 5

Antigenic material recognised by the innate immune system.
Taken up by phagocytes which become antigen presenting and present material to T-cells.
T-cells stimulate response via triggering production of:
-CD8+ - T-cell cytotoxin
-CD4+- T helper
-Plasma cells: produce antibodies or memory cells

Question 6

Describe the concept of herd immunity

Answer 6

• Vaccination reduces the presence of a disease in the individual
• Overall this decreases the likelihood of unvaccinated individuals becoming infected with the vaccination
• Protects individuals who cannot be vaccinated e.g. babies under 2 months, immunocompromised patients

Question 7

Describe the vaccination schedules for children

Answer 7

2/3/4 months: Diphteria, tetanus, polio, pertussis, haeminfluenza b
12/13 months: rotavirus
2/4 months: streptococcus pneumonia  
3 months: neiseria meningitis C.
3/4 years: influenza 
3 years and 4 months: MMR, DTPP
12-13: HPV
13-18:  DTPolio, neiseria meningitis C.

Question 8

Describe the vaccines that may need to be given to travellers

Answer 8

hep A, rabies, yellow fever, Japanese encephalitis, tick-borne encephalitis, typhoid.

Question 9

problems which may occur with vaccines?

Answer 9

• Not all pathogens can be treated by vaccination
• Immunocompromised patients cannot be treated with vaccines
• Does not last forever- may require boost
• May not produce memory cells
• Babies: cannot be immunised before 2 months. between 18-24 months not protected against capsulated pathogens, fewer FdC receptors, short term antibody production.
• Elderly: reduced production of plasma cells, Reduced response to vaccines
• Antigenic shift: influenza virus has 8 strains of RNA. when Co-host infections occur then genetic mutations are possible
• Cold chain network: standard set temp range at which the vaccine must be transported in order to be effective.