vaccines rationale successes problems nester 5 th edition chapter 17th
TRANSCRIPT
Nester Chapter 17
• Principles of Immunization• Naturally acquired passive immunity• Naturally acquired active immunity• Artificially acquired passive immunity• Artificially acquired active immunity
Principles of Immunization• Antiserum
– Serum containing antibodies
• Antitoxin– Serum protects against toxin
• Immune globulin– Passive immunization preparations contain
gamma globulins IgG.
• Hyperimmune Globulins– Sra of donors with high amount of
antibodies
Nester Chapter 17• Herd Immunity - the inability of an
infectious disease to spread in a population because of the lack of a critical concentration of susceptible non-immune hosts.
• Vaccine - a preparation of attenuated or inactivated microorganisms or viruses or their components used to induce active specific immunity.
Herd Immunity Figure 2
InfectiousAgent
Active Immunization or Recovery from Natural Disease
Non-ImmuneNo disease
Non-ImmuneDisease
Vaccines• Attenuated vaccine agents
– Either organisms or viruses that cause a sub-clinical or mild disease and that produce long lasting immunity.
– Antigen is intact, may decrease circulation of wild type
– Examples- mumps, measles, rubella, yellow fever and Sabin polio
Nester Chapter 17• Inactivated vaccine agents
– Antigen is altered slightly to still produce immunity without the disease
– Whole agents• Killed micro-organism or inactivated virus• Example- cholera, influenza, rabies and
Salk vaccine
– Toxoid• Inactivated toxins• Example- Diphtheria and tetanus
Inactivated vs. Attenuated Virus Vaccines Table 1
Property Attenuated Inactivated
Route of Administration Injection, oral, or nasal Injection
Dose of Virus Low High
Number of Doses Single Multiple
Duration of Immunity Long-term Short-term
Antibody Immune Response IgG and IgA IgG
Cell-mediated Immune Response Good Poor
Heat Lability in Tropics Yes No
Reversion to Virulence Rarely, OPV No
Cost Low High
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• Protein sub-unit vaccines– Key protein antigens or antigenic
fragments– Examples- acellular pertussis (aP)
• Recombinant vaccines – Subunit vaccine produced by
genetically engineered micoorganism– Example- Hepatitis B
Nester Chapter 17
• Polysaccharide vaccines– composed of the polysaccharide that
make up capsule– elicit a poor response
• Conjugate vaccine– improvement over purified– Haemophilus influenza type b and
Streptococcus pneumonia
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• Adjuvant– Inactivated contain a substance that
enhances the immune response to antigens
– Currently approved in United States is alum (Aluminum hydroxide and aluminum phosphate)
Comparison of the Antibody Response to Inactivated and Attenuated Vaccines – Figure 1
Time in Days
Antibody
Levels
Serum IgG - Both
Serum IgM - Both
Nasal IgA m- Atten
Serum IgA - Both
Duodenal – IgA - Atten
Nasal & Duodenal IgA - Inactivated
Nester Chapter 17
• Text 17.1 Some important vaccines• Text 17.3 Effectiveness of vaccines
in US (20th Century)• Text 17.4 Recommended schedule
in the US (2000)• Text 17.5 Diseases for which new
vaccines are sought
Vaccines
• Rationale – To produce, without harm to the
recipient, a degree of resistance sufficient to prevent a clinical attack of the natural infection
• Goals– To increase Herd Immunity– To help limit a present epidemic– To prevent a future epidemic
Vaccines
• Properties of an Ideal Vaccine– Promotes effective immunity– Confers lifelong protection– Has no side effects– Is stable– Is affordable in price not quality– Is seen to be good and effective
• No vaccine is perfect; some are close.
Prevention
• Phases of vaccine testing– Phase I
• testing for safety• ability to induce an immune response
– Phase II• determine optimum dose• kinds and duration of responses
– Phase III• effectiveness
Vaccines
• Duration of immunity varies:– For different vaccines.– For different groups of people.– Since protection does not always
relates to antibody level.
Vaccines• Contraindications - Do not give:
– Vaccines to someone with an acute disease or neurological disturbance.
– Attenuated vaccines to pregnant women.– Vaccines in the first trimester of pregnancy.– Vaccines to people on immunosuppressive
drugs or irradiation or with AIDS.– Vaccines made in eggs to people allergic to
eggs.
Vaccines
• Hazards– Mild to moderate pain at the injection
site– Fever and malaise for a day or two– Anaphylaxis - rare– Encephalopathy– Guillain-Barre syndrome– Epilepsy
Vaccines
• Hazards– Death from the vaccine viral strain– Aseptic meningitis– Demyelinating disease– Deafness– Sterility– Arthritis
Vaccines
• Safety considerations– Use a separate sterile syringe and
needle– Avoid errors - check the vial– Consider patient’s history– Consider contraindications– Keep careful records
Measles• Disease - Fig. 22.21
– 0-1000 cases/year - U.S.
– Death 1-2/1000 up to 150/1000 (15%)
– Secondary infections 85%
– Encephalitis 1/2000 1/2 die; 1/2 lose a function
– Pneumonia 1/20 -(5%)
• Vaccine– Encephalitis or
severe allergic reaction 1/1,000,000
– Thrombocytopenia purpura 3/100,000
– Aseptic meningitis 1/11,000 (mumps)
– Death is rare
Mumps
• Disease– 0-2 cases per 100,000 in
US– Hearing loss or deafness– Encephalitis– Pancreatitis– Aseptic meningitis 10%– ¼ cases in post-pubertal
males orchitis– 1 in 20 post-pubertal
females ovarian involvement pelvic pain
• Vaccine– Aseptic meningitis 2%
Rubella
• Disease– 0.1-0.2 cases per
100,000 in US– Congenital rubella
• Blind• Deaf• Retarded• Heart defects
• Vaccine– Arthralgia– Transient arthritis
2-3 weeks– Knee joint arthritis
may last 24 months
– Same as MMR
Polio
• Disease– 0 cases since
2000 from vaccine in US
– Cases come from outside US
– Paralytic death rate 1-2 %
• Vaccine– 8 cases/yr– 1 case/2,500,000
doses– Guillain-Barre
Chickenpox
• Disease– 10-60,000 cases
per year in US– 50-90 deaths– Zoster 77/100,000 – Encephalitis– Pneumonia
• Vaccine– Zoster 18/100,000
Hepatitis A
• Disease– 3-10 cases per
100,000 in US– Long
convalescence period of about a month
– 11% hospitalized
• Vaccine– Mild or of no
consequence– Same as placebo– Soreness and
redness at inoculation site
Hepatitis B
• Disease– 3-25 cases per
100,000 in US– Death 0.5-2%– Cirrhosis 4,000/yr.
• 25% die
– Cancer 800/yr.– 2-10% adult
carriers– Infants 90%
become carriers
• Vaccine– Autoimmune
disease• Lupus• Rheumatoid
arthritis
Bacterial Vaccine Types
• DPT– Diphtheria– Pertussis– Tetanus
• H. influenzae• Pneumococcal pneumonia
Diphtheria
• Disease– 0-5 cases a year
in US– Death 1/20– Heart– Kidney– Nervous system
• Vaccine– toxoid– Continuous crying
then full recovery 1/100
– Guillain-Barre– Brachial neuritis– Anaphylaxis
Pertussis
• Disease– 0.5-3.5 cases per
100,000 in US– Death 1/200– Encephalitis 1/20– Pneumonia 1/8
• Vaccine– Acute
encephalopathy 0-10 cases/1,000,000 immunizations
– Acellular vaccine has far fewer side effects especially of the neurological types
Tetanus
• Disease– 30-50 cases /yr. in
US (97% non-vaccinated)
– Mortality 30% in US
– Mortality 50% or more worldwide
• Vaccine– toxoid– Convulsions then
full recovery 1/1750
– Guillain-Barre– Brachial neuritis– Anaphylaxis
H. influenzae
• Disease– Age > 5:
0.5/100,000– Age < 5: 2/100,000– Death 3-7%
neurological disease– Pneumonia - death
50%– Epiglottitis– Septic arthritis
• Vaccine– Reduced
meningitis so much that S. pneumo has replaced H. influenzae
– Juvenile diabetes is a side effect
Pneumococcal pneumonia
• Disease– Death 5-20%
untreated– Resistance is a
problem• 1 state: >401
cases• 10: 101-400• 15 + 1: 1-100• 0: rest
• Vaccine