Vaccines 1 Flashcards
Brief History
Smallpox epidemic in Europe in 16th and 17th century. Variolation - induced some protection, reducing symptoms but some still developed smallpox and died. 1798- noticed milkmaids who had cowpox didn’t get small pox, scratched material from cowpox lesions into skin. Rabies- 1880s. Mid-20th century - many vaccines including diphtheria, pertussis and typhoid.
Whats a vaccine
Biological product which safely induces an immune response. Must contain an antigen. Broadly classified as live or inactivated
Properties of a good vaccine - Antigen
Specific or cross reactive to protect against multiple pathogens/strains but not-cross reactive against host.
Properties of a good vaccine - Delivery System
Low side effects: non-toxic, no chance of pathogenic reversion. Induces a strong and long lasting memory response. No boosters needed for better compliance. Effective against the target pathogen inducing the right sort of immune response. Not injected. No refrigeration chain required. Cheap to manufacture and distribute. Easy to administer
What are critical antigens?
Induce protective antibodies to be made e.g surface proteins of influenza/ clostridium tetanii toxin.
What is herd immunity
Sufficient proportion of a population immune to an infectious disease providing indirect protection to those who are not immune. Infection cannot spread in population from vaccinated individuals protecting susceptible individuals.
Contraindications for vaccines
Acute illness side effect. Pregnancy ( no live vaccines, no vaccines in 1st trimester). Immunocompromised ( Due to drugs or irradiation/ chronic illness). Allergy
Principles of Vaccination - Passive Immunisation
- Natural: Maternal antibodies passed to foetus or neonate.
Passive Immunisation - Artificial
Homologous pooled human antibody ( immune globulin) / globulins. Heterologous (equine) hyperimmune serum (antitoxin). Monoclonal antibodies e.g palivizumab for RSV.
Active Immunisation
- Bodys immune system stimuatled to produce immune response against a specific pathogen/ antigen
- Immune system
Exposed to antigen to induce production of antibodies and memory cells providing long-term protection against future exposure to the same pathogen to induce strong secondary immune response without causing illness from the primary challenge. Primary and secondary antigen challenges refer to different stages in this process.
Active Immunisation - Primary and secondary challenge
Primary antigen challenge involves vaccinated antigen exposure causing experience some symptoms of the disease if the antigen is a live or attenuated pathogen
Secondary immune response occurs when the
Immune system encounters the same antigen again at a different time naturally or via subsequent vaccinations. Much faster response, memory B cells quickly differentiate into plasma cells producing a large quantity of antibodies specific to the antigen. Memory T cells help to eliminate pathogen. may develop symptos but milder and of shorter duration.
Live attenuated vaccines adv and disadv
Live attenuated: Living but avirulent: Adapted to different host, genetically manipulated and grown in sub-optimal conditions. Adv: One booster. DisAdv: Reversion to virulence and poor stability
Vaccinations- Killed whole organism adv and disadv
Dead organism: Pathogen killed by chemical/ irradiations. Adv: Stable and long last lasting, safe, no reversion. DisAdv: Several doses, requires an adjuvant, inefficient.
Toxoid vaccines - adv and disAdv
Toxin causes the disease: toxin treated with formaldehyde. Adv: Stable and long lasting, safe. DisAdv: Not highly immunogenic requires an adjuvant
Subunit; Adv and DisAdv
Sub unit: Selection of antigens from the pathogen. Adv; Stable and long lasting, safe. DisAdv: Not highly immunogenic. requires an adjuvant
