Bacterial And Viral Vaccines Flashcards
What is the adaptive immune response?
Direct recognition of antigens by B cells, neutralisation of circulating antigens, production of antibodies.
Activation of B cells by T cells, production of long lived plasma and memory B cells
What is involved in T cell mediated immunity?
Activation of T cells by APC
Multiplication of T cells into effector T cells
Cytotoxicity, activation of B cells, memory T cells
What is the principle of vaccine?
Prime immune response so on subsequent encounter the memory response allow a more rapid and rigorous response to be made.
What is active immunity?
Induce and adaptive immune response in the host
What is passive immunity?
Transfer of immune effectors only eg immunoglobulin
What is antisera immunity?
Passive immunity, animal derived, specific for a certain toxin
What are the aims of vaccine?
Produce same immune protection which follows natural infection
Long lasting
Stop spread of infection
equally effective in all individuals
What are examples of immunoglobulin vaccine?
Varicella zoster ig
Human normal ig
Hep b ig
Tetanus ig
What are examples of anti toxins?
Diphtheria anti toxin
Botulinum anti toxin
What are examples of inactivated subunit vaccine?
Diphtheria, tetanus, acellular pertussis, inactivated polio, h influenzae b Influenza Meningococcal C Pneumococcal PCV, PPV HPV HAV HBV
What are examples of live attenuated vaccine?
MMR, opv, rotavirus, yellow fever
What is a live vaccine?
Attenuated strains which replicate in the host, cannot cause disease.
Ilicit good strong long lasting immunity
What are the advantages of live vaccines?
Single dose often sufficient
Strong immune response evoked
Local and systemic immunity
What are the disadvantages of live vaccines?
Potential to revert to virulence Contradicted in immunosuppressed Interference by viruses or vaccines and passive antibody Poor stability Potential for contamination
What are inactivated vaccines?
Suspension of whole intact killed organisms, pertussis, influenza, rabies, hepA
Acellular and subunit vaccines contain one or few components of organism important in protection
What are the advantages of inactivated vaccines?
Stable
Constituents clearly defined
Unable to cause the infection
What are the disadvantages of inactivated vaccines?
Need several doses
Local reactions common
Adjuvant needed
Shorter lasting immunity
What are combination vaccines?
Give several vaccines at one time
Ensure that immune responses are equivalent to single vaccines
Adverse effects are no worse or frequent
What is SSPE?
Sub acute sclerosing pan encephalitis associated with measles
ITP associated with MMR
What is the relationship of adverse events with live and inactivated vaccines?
Live- frequency of adverse events falls with number of doses
Inactivated- frequency of adverse events increases with number of doses
What is the timing of inactivated vaccine reactions?
Generally within 48 hrs following vaccination
What is the timing of live vaccine reactions?
According to time taken for virus to replicate
Measles- malaise, fever, rash, 6-11 days
Rubella- pain, stiffness, swelling of joints, 2nd week
Mumps- parotid swelling, 3rd-6th week
When should you avoid live vaccines? Especially bcg, polio
Patients having chemo for malignancy
Patients less than 6 months after BMT
Children on high dose steroids or cytotoxics
Pregnant women (no evidence of harm from MMR)
What vaccines can be given to HIV positive patients?
MMR, inactivated HIB,DTP, HBV
Not BCG
Not yellow fever vaccine
How do immunoglobulins work?
Provide passive antibody and can be used prophylactically before or after exposure
Cannot be used to test established disease
Can attenuate disease (antitoxins can treat)
What are examples of immunoglobulin therapy?
VZIG- used in susceptible pregnant women, neonates or immunosuppressed patients exposed to chicken pox
HBIG- prevention of HBV, in conjunction with vaccine
NHIG- prevention of HAV, rubella and polio
How is rotavirus given?
Oral liquid vaccine