immunization Flashcards
Two key public health measures have a major effect on lowering the incidence of infectious disease:
- Public sanitation
- Vaccines
Potable water supplies, sewage disposal, improvements in housing
Prevention of infectious diseases by inducing immune responses
Vaccine
An immunizing agent derived from microorganisms
Vaccine types
- Live, attenuated microorganisms
- Killed (irreversibly inactivated) microorganisms
- Products or derivatives of microorganisms
Types of immunization
Active immunization - administration of a vaccine
Passive immunization - administration of exogenously produced or preformed antibodies
Passive immunization
newborns?
postexposure treatment
Injection of purified antibody or antibody-containing serum to provide rapid, temporary
protection or treatment.
Newborns receive natural passive immunization- maternal immunoglobulin that crosses the placenta and is present in breast milk
Uses of passive immunization:
- To prevent disease after a known exposure
- To ameliorate the symptoms of an ongoing disease
- To protect immunodeficient individuals
- To block the action of bacterial toxins and prevent the diseases they cause
Human Immune Globulins used against what diseases?
Hepatitis A Hepatitis B Rabies Respiratory Syncytial Virus Varicella tetanus
animal antitoxins used against
Botulism
Diphtheria
passive immunization Limitations
sometimes antiviral antibody titers not high enough
contamination with other infectious agents
need to use early after exposure, often this is not possible
some viruses have a limited extracellular phase
herpesviruses, enteroviruses
ab containing products and vaccines
Antibody-containing products can inhibit the immune response elicited by vaccines
Administration of vaccines should be delayed until passive antibody has degraded
active/passive immunity for diseases with long incubation
For diseases with long incubation periods both active and passive immunization are
used for postexposure control
Hepatitis B, rabies, tetanus
Active immunization
Use of vaccines to elicit immune responses
Inactivated, subunit, and killed vaccines Live vaccines (attenuated)
Inactivated, subunit, and killed vaccines
No risk of infection
Use large amounts of antigen
Inactivate or kill by chemical treatment (e.g. formalin) or heat
for bacteria, viruses, or bacterial toxins
Purify or synthesize subunits or components of the infectious agent
Adjuvants
modern ones?
influence?
Adjuvants required to boost the immunogenicity of Inactivated, subunit, and killed vaccines
Alum (aluminum salt)
Modern adjuvants are designed to be or to mimic PAMPs
bacterial cell wall components
synthetic polymers
bacterial toxins (attenuated)
Adjuvants influence the type of immune response
Th1 or Th2
secretory IgA
Some disadvantages of Inactivated, subunit, and killed vaccines
- Immunity is not usually long-lived (generates a Th2 response that does not elicit effective immune memory)
- Immunity may be humoral and not cell-mediated
- The vaccine does not usually elicit a local IgA response
- Booster shots are required
- Larger doses must be used
vaccines/dieases using these methods of immunization
toxoids?
inactivated?
capsular polysaccharides+?
toxoids: Corynebacterium diphtheriae, Clostridium tetani
inactivated (killed) bacteria: Vibrio cholera
capsule or protein subunits of bacteria
Capsular polysaccharide vaccines: Haemophilus influenzae B,
Conjugate these because polysaccharides are poor immunogens
Hib polysasccharide + diphtheria toxoid
Viral vaccine types
inactivated viruses (polio, hepatitis A, influenza, and rabies) protein subunits of viruses (hepatitis B)
Active immunization: Live vaccines use? host rxn? # doeses? longevity? adjuvant?
Use avirulent or attenuated microorganisms
Immunization resembles the natural infection
host reaction progresses through Th1 and Th2 immune responses: humoral, cellular, and memory immune responses are developed
Only a single dose usually required
Immunity is generally long-lived
No adjuvant required
live vax disadvantages
- Vaccine microorganism may still be dangerous for immunosuppressed people or
pregnant women, who do not have the immunologic resources to resolve even a
weakened infection - The vaccine microorganism may revert to a virulent form (for viruses)
- The viability of the vaccine must be maintained
Live Bacterial vaccine example
why not used?
Calmette-Guerin bacillus (tuberculosis)
attenuated strain of Mycobacterium bovis
not routinely used in United States because vaccinated individuals show a false-positive reaction to
the tuberculosis test used in this country (PPD test = purified protein derivative test)
live vax viral vax example
MMR vaccine measles virus mumps virus rubella virus Varicella-zoster virus (also available as part of MMRV vaccine)
correlates of protection
the host immune responses associated with disease protection
Vaccines that protect solely or principally by induction of serum antibodies
hepA and tetanus
Secretory antibodies play a role in protection against infections caused by
agents that must first replicate on mucosal surfaces, which disease
rotavirus
Vaccines for which T-cell responses are essential include
measles and varicella
SARS-CoV-2 vaccines for generating active immunity
mRNA, viral vector, and protein subunit vaccines encoding the Spike protein (or parts of)
mRNA vaccine encoding the Spike protein
Pfizer - BioNTech & Moderna
mRNA enters cells and is translated into parts of Spike
active immunity
Viral vector vaccine encoding the Spike protein
engineered harmless adenovirus (DNA virus) that infects
cells and then produces parts of Spike
Johnson & Johnson - Janssen
active immunity
Protein subunit vaccine containing parts of the Spike protein
also contains adjuvants (saponins)
Novavax
active immunity
Treatment for COVID-19 based on passive immunity to SARS-CoV-2
mAb- binds SARS-CoV-2 virions and“neutralizes” them, which means it blocks the virus from interacting with ACE2 receptors and entering cel
