BSC 438 Vaccines

Active Immunization

injecting antigen, stimulating immune system, antigen-specific antibodies and T cells made

includes vaccines

Passive Immunization

protective antibodies are administered, injection of immunoglobulin, antitoxins, breastfeeding

What are the requirements of an effective vaccine?

1. it should have a favorable benefit-to-risk profile

2. it should stimulate B-cell (antibody) and T-cell (cell mediated) responses

3. it should result in long-term memory

4. it should not require many boosters

5. it should protect against the natural pathogen

What are the three different vaccine goals?

prevent infection, prevent symptomatic illness, prevent severe disease and death

What are the four basic types of vaccines?

1. killed whole cells or inactivated viruses

2. live, attenuated (weakened) bacteria or viruses

3. purified components (antigenic subunits) of an infectious agent (acellular or toxoid)

4. DNA or RNA vaccines

Killed whole cells or inactivated viruses vaccines

use inactivated (dead) organism

antigenicity remains

ex: cholera and rabies

Live, attenuated (weakened) bacteria or viruses vaccines

weakened to reduce disease risk while retaining immunogenicity

often mimic infection and generate strong immune responses

Herd Immunity

occurs when a large portion of the population is immunized

can reduce transmission between people

Why is measles a favorable vaccine target?

Antigenically stable (one serotype)

Two doses of MMR give strong, durable protection

Vaccination can interrupt transmission at high coverage

Why are influenza vaccines reviewed and updated annually

H and N change over time

Influenza A has 8 RNA genome segments that can reassort

Antigenic drift reduces recognition by existing antibodies, and protection against the infection can wane

What are the difficulties with the COVID vaccine?

spikes evolve under immune selection and the protection against the infection wanes and varies by variant

Why does the nose matter in regards to vaccines?

Flu and COVID began replicating in respiratory tissues

Compare Measles, Flu, and COVID

measles: stable antigen, durable protection, transmission can be interrupted

flu: antigenic drift, waning protection, annual updates

COVID: antigenic evolution, waning infection protection, updated vaccines

Vaccine Adverse Events Reporting System (VAERS)

people can report post-vaccination health issues such as allergic reactions, intestinal conditions, blood clots, etc

could include problems that may or may not be related to a vaccine

serves as an early warning system for unforeseen problems with approved vaccinations

What is actually in a vaccine?

active component, adjuvants, some include stabilizers, preservatives, and small residual materials

Vaccine Active Component

an antigen-or instructions for cells to make an antigen- trains immune responses

Adjuvants

Substances that help vaccines work better by boosting the body’s immune response. Tiny amounts of aluminum salts have been used for decades

Preservatives

Typically added to multidose vaccine vials to prevent contamination once a vial is opened

use ethyl mercury- broken down and excreted faster from body compared to methylmercury

Stabilizers

Used to keep the antigen stable during shipping and storage. Can include sugars, amino acids, proteins, and gelatin

May also contain surfactants or emulsifiers to keep the ingredients blended together and prevent clumping