Vaccines Flashcards
What is post-exposure immunization? Give an example of a post-exposure vaccine
The use of a vaccine conferring both passive and active immunity, important with diseases having acute onset and fatal incomes
I.e. Rabies shot: immunoglobulin and vaccine given
or
Toxoid (immunogenic) and antitoxin given for diphtheria exposure
Why is the measles vaccination delayed until one year?
Maternal antibody can interfere with the immunization by binding the immunogenic antigens and having the infant’s immune system fail to form an immune response
When is the rapidity of the anamnestic response important?
For diseases with a short incubation period -> resasons why children receive multiple injections of tetanus toxoid to keep circulating antibody levels high
What is a vaccine paradox that causes waning immunity?
Fewer individuals in the population having the disease limits “natural boosting”, when circulating Ig’s actually make a difference. As a result, multiple booster shots are needed to keep antibodies at protective levels
This is a problem right now with Rubella
Why are subcellular vaccines easier to store than live?
Many live vaccines need to be kept cold to remain stable, and some countries lack the resources to refrigerate vaccines
What is the primary way in which live, attenuated viruses are attenuated? Why are they better?
Passage through a non-human host, reducing the virulence
Better because they induce a stronger, longer-lasting immunity
What major vaccines are live, attenuated?
MMR, Polio (Sabin), Yellow fever, BCG
What are the major risks associated with live attenuated vaccines?
- Insufficient attenuation (done randomly) or reversion to wild type
- Persistent infection induced by living virus from vaccine
- Risks to fetuses or immunocompromised
What is the Salk polio vaccine? When are these types of vaccines used? What are the issues?
Inactivated polio via formaldehyde
Used when risk of reversion is too high, issue is reduced immunogenicity and multiple doses are needed
What major vaccines are killed / inactivated?
Rabies, influenza, polio (salk), bordetella pertussis, yersinia pestis
What are subcellular vaccines, and when are they conjugated?
Vaccines in which protective immunity can be induced via some component of the pathogen. I.e. toxoids or capsular polysaccharides). Conjugated when one component wouldn’t be immunogenic enough. I.e. Hib vaccine: capsular polysaccharide is conjugated with diphtheria or tetanus toxin in order to invoke a greater immune response
What is the problem with the immune response induced in the Sabin vs Salk vaccine?
Sabin - live, attenuated - can be given orally and induce protective sIgA response, the normal fecal-oral route of polio (GI infection)
Salk - inactivated - induces serum IgG response, no mucosal immunity for protection where the virus actually strikes
However, they have comparable effectiveness
Why do polysaccharide antigens fail to induce a T cell response?
They are ineffective at inducing a secondary response at under two years of age, so they must be conjugated to a toxoid
What types of vaccines do asplenic individuals really need?
Vaccines against encapsulated pathogens since they are not cleared by the spleen - i.e. Hib. Increased risk of infection by these organisms.
What is one live, attenuated vaccine the HIV-infected patients should still have?
MMR vaccine - risk of death from natural infection far outweighs the potential vaccine complications
