VACCINES!!!! Flashcards
Immunization
process by which a person or animal becomes protected against a disease
often interchangeable with vaccination or inoculation
How is it that smallpox was eradicated?
Humans are the only host
were able to identify a vaccine target
effective vaccine
virus is stable
Vaccine
product that produces immunity therefore protecting the body from the disease
Active immunization
directed at a specific organism
injection of killed, weakened or subunit of an infectious organism in order to elicit an immune response which is effective at preventing the disease when encountered
Passive immunization
alternative to vaccination for those already infected or are immunodeficient
may be acquired naturally (breatmilk) or artifically (Ab containing preparation)
Two types of Ab preparations are available
- normal human immunoglobin (pooled sera)
- specific hyper immune human immunoglobin
- preformed antibodies taken from an individual (s) during convalescence or following vaccination
what are requirements for a successful vaccine?
safety
induction of protective immune response (effectiveness, proper cell responses must be evoked)
Practical issues - affordable, stable, administration, perception
Vaccine efficacy is related to
duration of immunity elicited
Traveler’s vaccines last
a short period
months to years for Cholera
Two years for TAB vaccine - typhoid/parathypoid
DTap vaccine
lasts 3 to 5 years
BCG vaccine
5 or more years
Vaccines that last about ten years
Tetanus (Td) yellow fever
Vaccines with solid immunity/lifetime
MMR - measles, mumps and rubella
What are efficacies of some vaccines given?
Absolutely protective - 100% - yellow fever vaccine
almost abs. protective - Variola, measles, mumps, rubella, diphtheria and tetanus
highly protective - (80-95%) - polio, BC, Hep B, and pertussis
Moderately protective - (40-60%) - TAB, cholera vaccine, and influenza
Herd immunity
acts as firewall to block or slow disease transmission
since some vaccines do not cover 100% of people, some people given the vaccine will remain unprotected
some people are not able to receive vaccines - the immunocompromised - so this is most effective way to protect these ppl
for non infectious diseases - there is no herd immunity
Additives used in production of vaccines may include
suspending fluid - sterile water, saline, or fluids containing proteins
Preservatives and stabilizers - helps it remain potent and unchanged - albumin, phenols, glycine
adjuvants or enhancers to help the vaccine to be more effective
Some common ingredients in vaccines
aluminum gels or salts - adjuvant
antibiotics - no vaccine in the US has penicilllin
Albumin - egg protein in influenza and yellow fever vaccines
Formaldehyde - to inactivate bacterial products for toxoid vaccines (most is removed before packaging)
Monosodium glutamate and 2-phenoxy-ethanol - stabilizers in a few vaccines, help vaccine remain unchanged when exposed to heat, light, acidity or humidity
thimersol - mercury containing preservative, in vials of vaccine that contain more than one dose to prevent contamination, All US vaccines are available with no or trace amounts of thimersol
Types of vaccines
Live attenuated vaccines
Non living whole organisms vaccines
Non-living subcellular fragment vaccines
Passive immunization
Live attenuated vaccines
microbes with artificially reduced virulence
microbes with naturally reduced virulence for humans
Non-living whole organism vaccines
inactivated/killed whole organism
Non-living subcellular fragment vaccines
toxoid - inactivated toxin
recombinant vecor expressing protein of interest
surface antigen alone - peptide or capsular polysaccharide
Conjugate vaccines
In live attenuated vaccines where the microbe has artifically reduced virulence usually
do not cause serious disease in healthy ppl
Genetic roulette
randomly mutated by imposing unusual growth conditions
low temp, abnormal host cell, and select for loss of virulence with continued antigenicity
Measles, mumps, rubella, influenza, VZV, polio (sabin), yellow fever, BCG
site directed mutations and deliberate deletions of virulence genes
Microbes with naturally reduced virulence for humans
pathogen from related species can be used to elicit protective response
vaccinia virus for smallpox
rotavirus vaccine - reassortant virus with gene segments from human and animal rotaviruses or an attenuated human rotavirus
Advantages of live attenuated vaccines
elicit a better memory response than killed vaccines, therefore, provide longer-lasting immunity
- replication competent (to an extent)
- localize to site where protection is required - OPV (sabin) vaccine induces gut immunity (IgA) vs. IPV (Salk) inducing IgG (IM)
Disadvantages of Live attenuated vaccines
instability if cold chain not maintained
potential for reversion to wild-type and production of disease
small probability of causing serious disease in IC/immunodeficient pts
-OPV (Sabin) vaccine
-Smallpox vaccine in person with eczema (immunodeficient) or HIV pt
Attenuation
the process of weakening a pathogen
- serial passage in cells cultured in vitro (OPV)
- adaptation to low temperature (intranasal influenza vaccine)
What is serial passage?
pathogenic virus is isolated from a pt and grown in human cultured cells then cultured virus is used to infect monkey cells then virus acquires many mutations that allow it to grow well in monkey cells
Lastly, the virus no longer grows well in human cells amd may be a candidate for a vaccine