Vaccines (Lec. 24) Flashcards
Identify the general immunology principles underlying vaccinations
Artificial active immunity; prompts an immune response (T cells and B cells) to the antigens in the vaccine, which results in the formation of memory cells and antibodies with specificity to those antigens. When the vaccinated individual encounters the real microbe at a later time, memory cells act quickly to prevent infection. NOTE: do not provide immediate protection (~2 weeks).
Identify types of active and inactive vaccines
Active vaccines: attenuated vaccines and vector vaccines.
Inactivated vaccines: whole-agent vaccines or parts of a pathogen (mRNA vaccines or subunit vaccines: purified subunit, toxoid, or conjugate).
Describe live attenuated vaccines
An active virus or live bacterium rendered non-pathogenic; microbes that can multiply in the host but are too weak to cause disease). Provide best immune response and closely mimic natural infection; however typically need refrigeration and may not be safe for immunocompromised people. Very rarely, there can be a back-mutation to restore that virus or bacterium’s virulence (very bad).
Describe recombinant vector vaccines
Genes encoding important antigens are identified and packed inside a harmless virus (vector), which is then injected into the body. Good immune response, very safe, often requires refrigeration. May require boosters to achieve full immunity.
Describe whole-agent vaccines
Consists of an entire dead cellular pathogen or whole inactivated virus. Good immune response, safe for immunocompromised patients, usually stable at room temperature. Boosters are required to achieve full immunity.
Describe subunit vaccines
Consist of purified antigens (the immunogenic portion of the pathogen). Require adjuvants. Provide good immune response; very safe, usually stable at room temperature. May require boosters to achieve full immunity. Public is wary of adjuvants due to aluminum additives.
Subunit vaccine types:
- Purified subunit: purified antigenic components of the pathogen
- Toxoid vaccines: purified and inactivated toxins
- Conjugate (or polysaccharide) vaccines: polysaccharide antigens conjugated to a more immunogenic protein antigen because children <2 years old do not respond to T-independent antigens like capsular polysaccharides
Describe nucleic acid vaccines
Never been done and made commercially available until COVID. Instead of giving a whole virus or even giving a protein of that virus, DNA or RNA that encodes those proteins can be used as the subunit. Host cells will translate the genes and make the antigens. Good immune response, very safe, results in a humoral and cellular immune response. Requires boosters for full immunity and may require ultre-refrigeration.
State what adjuvants are and describe their purpose
Pharmacological additives that increase immunogenicity; often increase uptake by APCs. Improve the innate immune response. Often have additives like aluminum.
Define vaccine hesitancy
Refers to delay in acceptance or refusal of vaccines despite availability of vaccine services. Replaces terms like anti-vaxxer. Is complex and context-specific; varies across time and place. Influenced by complacency, convenience, and confidence. Factors: perception, worries, safety concerns, social norms, education, information sources, vaccine availability, consent, delay, refusal. Common reasons behind vaccine hesitancy: autism, flu vaccines, mistrust of science, belief that natural infection is “better”, religious or cultural practices against medical intervention, moral objections to the use of chicken eggs, animal cells, or human cells in vaccine production.
Describe factors that contribute to the re-emergence of vaccine-preventable diseases
Lack of herd immunity that usually would be provided by high rates of childhood immunization, but now there’s increased vaccine hesitancy and declining vaccination rates. Also travel to regions with high disease prevalence, inadequate access to vaccines in certain populations, and potential changes in the pathogen itself.
Explain herd immunity and describe how it protects non-immunized people
Communal immunity that protects unvaccinated individuals if the majority of the population is vaccinated. Prevents a pathogen from finding enough susceptible people in the community to persist and protects those unable to receive immunizations.
