Principles of immunisation Flashcards
Active immunisation
Process of exposing the body to a specific antigen to generate an adaptive immune response. Takes days/weeks but long lasting (sometimes lifelong).
Natural= infection or exposure
Acquired= immunisation vaccines
Stimulates body’s own immune response and antibodies
More powerful system- recognising antigen- creates immunological memory- if antigen returned it would be a lot more effective.
Passive immunity
Process of providing IgG antibodies to protect against infection. Gives immeiate, short-lived, temporary protection. No memory.
Natural passive immunity comes from transfer of maternal immunoglobulins (IgG) from placenta or milk from breastfeeding that give passive immunity to new born baby.
Artificial passive immunity comes from immunoglobulin therapy or immune cells. ie taking serum from immune individuals, pooling this, concentrating the immunoglobulin fraction and then injecting it to protect a susceptible person. Quick fix, no memory.
What is immunoglobulin
immunoglobulins fight antigens. Any of a class of proteins present in the serum and cells of the immune system, which function as antibodies.
Advantages of passive immunity
Gives immediate protection
quick fix
Disadvantages of passive immunity
- Short term effect- no immunological memory
- Serum sickness- incoming antibody is recognised as a foreign antigen by the recipient and results in anaphylaxis
Graft versus host disease (cell grafts only) incoming immune cells reject the recipient. They go on the offensive and attack the host’s tissues.
What is meant by the term ‘vaccination’?
It is the administration of antigenic material (a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a pathogen.
Which vaccines might travellers need and why?
Hep A- liver infection spready by faecal-oral route
typhoid- eating or drinking food or water contaminated with the feces
cholera- contaminated food and water
Rabies- a bite from rabid animal- causes inflammation of the brain
Permanently, who are there restrictions to vaccinations to?
those with specific allergies
immunocompromised patients- cannot be given live attenuated vaccines as individuals may develop disease as have low immunity to
fight/recover from the vaccine.
What does ‘contraindication’ mean?
conditions in a recipient that increases the risk for a serious adverse reaction
Herd immunity
increasing the number of resistant hosts in the population therefore increases herd immunity.
Herd immunity threshold
the density of resistant hosts required in a population to prevent an epidemic. Vaccinated individuals are less likely to be a source of infection to others
What is the 6 in 1 vaccine?
Common childhood vaccine. Protects against: diphtheria, tetanus, whooping cough, polio, Hib (Haemophilus influenzae type b) and hepatitis B
MMRV
measles, mumps, rubella, varicella (chickenpox). Vaccine against measles.
Measles
one of the most contagious viral diseases. Most unpleasant and dangerous of children’s diseases. Results in rash
Mumps
caused by a virus- can lead to meningitis
Rubella
dangerous to unborn children
temporarily, who are there restrictions to vaccinations to?
those with febrile illness- having or showing symptoms of it
those who are pregnant- cannot be given live attenuated vaccines
Give 2 differences between the primary and secondary exposure to an antigen in terms of antibody concentration and rate of response?
Primary - low Ab conc.
Secondary - high Ab conc.
Primary - slower response
Secondary - faster response
what is an adjuvant?
Adjuvants may be added to a vaccine to boost the body’s immune response to an antigen.
What is commonly added to human vaccines that act as an adjuvant?
Aluminium salts
what is an epitope?
the part of an antigen molecule to which an antibody attaches itself
Describe how an immune response occurs
small doses of an antigen are given to trigger an immune response. It causes activation of B cells which produce antibodies for the antigen. They also then produce memory B cells fro future immune responses to this specific antigen.
What types of vaccinations are available for active immunisation?
Live attenuated (LAV)
inactivated (killed antigen)
subunit
Live attenuated
contain a version of the living microbe that has been weakened in the lab so it can’t cause disease.
They elicit strong cellular and antibody responses and often confer lifelong immunity with only one or two doses.
Inactivated vaccination
the disease-causing microbe is killed with chemicals, heat or radiation. These vaccines are more stable and safer than live vaccines because the microbes can’t mutate back to their disease-causing state. Most inactivated vaccines, however, stimulate a weaker immune system response, so require several doses or booster shots to maintain a person’s immunity.
Subunit vaccine
instead of an entire microbe- subunit vaccines include only the antigens that best stimulate the immune system e.g epitopes. Because subunit vaccines contain only the essential antigens and not all the other molecules that make up the microbe, the chances of adverse reactions to the vaccine are lower.
toxoid vaccine
these vaccines are used when a bacterial toxin is the main cause of illness. They can inactivate toxins. Toxoids are harmless toxins that teach the immune system to fight off the natural toxin.
how is passive immunotherapy a ‘quick fix’ with no memory
because you are giving antibodies from immune person to other person, person receiving them doesn’t have to make own specific antibodies to fight infection so no plasma cells basically which means no memory
of infection just quick fix
