Vaccines

Question 1

History of Vaccines

Answer 1

Edward Jenner in 1796 injected samples from cowpox lesions into people to prevent small pox after seeing milkmaids getting a less severe cowpox disease and resisting smallpox

Question 2

Passive Immunization

Answer 2

Transfer of maternal IgG antibody to the fetus in utero or IgA to the child’s gut from breast milk.

Injection of antibody against the pathogen or toxin. Protection lasts weeks to months. (ex. pre-exposure Hep A serum)

Question 3

Active Immunization

Answer 3

Vaccination with an antigen that elicits an immune response.

Prior exposure to pathogen or related pathogen.

The memory response (T cells, antibodies) protects from reinfection and/or disease.

Question 4

Immunoglobulins available for post-exposure prophylaxis

Answer 4

Hep A 
Hep B 
Measles 
Rabies 
Chickenpox, VZV 
CMV 
Tetanus 
Botulism 
Diptheria 
Ebola 

bacterial ones do not block infection but block toxin which causes them to get sick

Question 5

What does a vaccine do?

Answer 5

Block the initial infection - sterilizing immunity

Block spread in the body or establishment of chronic infection (HBV)

Lesson symptoms of infection

Shorten the time of infection

Block the action of toxins (tetanus - bacteria)

Reduce or eliminate the risk of virus-caused cancers (HBV, HPV)

Reduce opportunity of spread to other individuals lowering the incidence in a population.

Herd immunity.

Question 6

Inactivated (killed) Vaccine

Answer 6

can take an infectious agent and you can render it noninfectious and inject it. So it’s inactivated or killed.

Usually fixed in formaldehyde (formalin)

Question 7

Examples of Attenuated Vaccine

Answer 7

Sabin Polio Vaccine
Measles, Mumps, Rubella (MMR)  
VZV only 
Yellow Fever
Influenza nasal spray (FluMist)

Question 8

Attenuated (live) Vaccine

Answer 8

to immunize somebody with a virus that is weakened and causes no or less disease because when you are generally infected with an infectious agent, your immune response is much more robust

Question 9

Examples of Subunit Vaccines

Answer 9

HBV

HPV

Question 10

Vector Vaccines

Answer 10

in development
Use a different, non-pathogenic virus to deliver genes for the one you are immunizing against.

ex, EBOLA; use an attenuated animal virus vesicular stomatitis virus (VSV) and insert the gene for the Ebola envelope protein.

People are then infected with the rVSV-EBOV vaccine, the virus replicates a
little but does not cause disease

Question 11

DNA Vaccines

Answer 11

Deliver a gene for a viral component directly using DNA injected into the muscle.

The DNA is taken up by muscle cells that then make proteins for the antigenic component of the virus.

Question 12

Attenuated v. Inactivated

Answer 12

1) Number of doses is usually lower with a live vaccine, not always, but very frequently.
2) You don’t need an adjunct because the natural replication of the virus provides the inflammatory response that you’re looking for with an adjunct.
3) You often also don’t get good T-cell responses with inactivated. Cell mediated immune responses are usually much better with an attenuated vaccine versus a killed or sub unit and that can be important because you need that cellular immunity to support the antibody production and to also have killer cells.

Question 13

Herd Immunity

Answer 13

Vaccines are usually not 100% effective - some people will not develop a protective immune response and not all people will receive a vaccine.

If enough people are successfully vaccinated, the chain of transmission can be broken and the incidence of infection will drop.
The viral reproductive ratio (r) is reduced to r<1

Question 14

Adjuvants

Answer 14

Agents such as aluminum salts or oil emulsions (e.g. squalene) added to non-live vaccine formulations.

Adjuvants enhance the immune response:

Hold the antigen in place, allowing a greater length of time for a response and aiding in presentation of antigens to macrophages.

Stimulate localized inflammatory/innate immune response which recruits T and B cells to the site, thus enhancing the adaptive response.

Can sometimes allow for less antigen to be used

Question 15

Preservatives

Answer 15

Thimerosal (Merthiolate)

Prevents growth of bacteria and fungi
Added to vials containing multiple doses of vaccine

Thimerosal is a compound containing ethylmercury it is cleared from the body more quickly than:
Methylmercury is the mercury compound that is in fish that we try to avoid it can build up in the body and be toxic.

Thimerosal was taken out of childhood vaccines in the United States in 2001.