Theme 3 & 4: Vaccination & healthcare Flashcards
2 main functions of a vaccine. What can be measured to see the effectiveness of a vaccine
-Vaccination protects you against the pathogen, as well as conserves your immunity you already have, against other infections
- Antibody level in the serum
- T cell production
Function of memory B cells and T cells
- memorize the characteristics of the antigen during initial infection so in secondary infections, it triggers an accelerated and stronger immune response, where IgG predominates.
- Memory B cells -faster antibody production. Class switched Ig
- this memory is long lasting and maintained in the absence of antigen
How was small pox eradicated (1979)
- Cowpox and smallpox viruses share some surface antigens
- So injecting people with cowpox induced antibody production which could also be used to neutralise the smallpox virus
-This strategy doesn’t work in other cases unfortunately
What a vaccine needs to be in order to be effective and practical.
- safe: not cause illness
- Protective against illness from the pathogen, lasting for several years
- Induces neutralising antibodies to prevent the pathogen infecting irreplaceable cells
- Induces protective T cells
- Practical considerations: low cost, easy storage, few side-effects, easy administration, long shelf life, stable, don’t clump
Explain briefly the main types of vaccines (Vaccines based on killed organisms, based on attenuated organisms, live-attenuated vaccines, recombinant vaccines, RNA vaccines, recombinant viral protein vaccines, Capsular polysaccharide vaccines) Give examples of vaccines/ diseases for each
- Vaccines attenuated on killed organisms: culture lots of infective organism, then inactivate them using chemicals/ heat/ radiation. It still has their antigens but unable to replicate. (eg. flu vaccine)
- live-attenuated organisms: cultured virus inserted into non-human cells, so no longer replicates in human cells, but body recognises the antigens. Better immune response. Not very effective in adults (eg. BCG for TB)
- Recombinant: Insert antigen producing gene into plasmid. Plasmid infects yeast and makes lots of proteins which can be extracted and used as a vaccine (HPV, Hep B, meningitis)
- RNA vaccines: extract viral RNA, put in lipid coat. -80C storage. (SARS CoV2, as it removes the spike proteins)
- Recombinant viral protein vaccines: make spike proteins in lab. Elicits immune response when injected. (Covid)
- Capsular polysaccharide vaccines: Need for conjugation to toxin to be effective in all patients
What are adjuvants used for in vaccines. What substance can be used for this.
What 4 other elements are in the vaccine formulation
- Substances added to vaccine to encourage sterile inflammation, because the pathogen alone may not elicit a good innate response
eg. aluminium salts - Preservatives
- Stabalizers (prevent chemical reactions)
- Surfactants (prevent clumping)
- Dilutent (sterile water)
What is passive immunisation
- person receives antibodies or lymphocytes that have been produced by another individual’s immune system
- occurs naturally from mother to foetus, during development, breast feeding (IgA), across placenta (IgG).
Why passive immunity is important for a baby
- mother’s immune cells and Ig genes transferred to baby
- this is essential because it takes time for a baby’s immune system to fully develop (6 months after birth)
What is herd immunity and how is it achieved
- Herd immunity established when a significant amount of the population is vaccinated
- If the majority of the population are protected then the susceptible minority are protected, as low probability of pathogen finding these people.
- infection harder to spread
Are diphtheria, polio and measles eradicated
-No, although vaccination has been successful and so very low incidence
Measles: transmission, symptoms, severe complications
- Droplets in coughs and sneezes
- sneezing, runny nose, fever, tiredness, aching, loss of appetite, diarrhoea, conjunctivitis, spots merging to blotches, Koplik’s spots in mouth
virus infects leukocytes, suppressing immunity
-Severe complications: Encephalitis, meningitis, febrile convulsions, pneumonia, hepatitis, damage to hearing, death.
What is social demography
- The relationships between economic, social, cultural, and biological processes influencing a population
- these challenges affect the implementation of vaccines
When was widespread vaccination introduced, how many vaccines are there now
- 1950s
- vaccines against 26 infectious diseases
Why is the HIV and malaria vaccine so hard to develop
- Malaria is a challenging vaccine to develop due to complex life cycle
- HIV: high mutation rate
What key things are tested for in the 4 stages of clinical trials for vaccines. how many people are involved in each stage
- Phase I (<100 people)= safety and dose
- Phase II (>100 people)= side effects, if it elicits an immune response, consistency
- Phase III (>1000 people)= efficacy, safety, rarer side effects.
- Double blind trial used to compare instance of disease with patients injected with placebo and with the vaccine.
-Phase IV: post marketing surveillance
What affects people’s views on vaccines. Why people are against them
- Given false information about side effects (info spreads fast with social media)
- Misconseptions of risk: don’t realise that risk from the vaccine are completely outweighed by getting the disease
- Media tends to focus on the very small studies
- Fear of needles
- Cost of getting the vaccine
- Campaigns: anti-vaxxers
- Religious and cultural beliefs
- Mistrust of science, medicine, government, healthcare systems
- Ignorance of disease- don’t know how fatal it can be
How you would explain what a vaccine is to a patient and why they are important
- Vaccines provide immunity to a particular infectious disease. Protects the individual and also the population as it reduces it spreading
- The vaccine teaches your body to make antibodies that protect you against the pathogen if you were to become exposed to it
- It contains a weakened or inactivated microbe, or an agent that resembles its toxins or surface proteins. It elicits an immune response, so that our body has memory and is immune to secondary exposure
-So for example, for covid, the spike proteins on the virus is what allows it to infect human cells. So by creating the protein in a lab, we can inject it into people so that it elicits an immune response and train our body to make antibodies for it, but without any viral replication and infection. The immune response means that our body has memory and immunity to the disease if we were to become exposed to it.
What demographic factors compromise vaccine effectiveness/ implementation
- poor healthcare and low income countries
- Porous borders, so easily spread
- Political issues: government not giving out info, loss of trust
- Ageing and increasingly obese populations so vaccines less effective
- Isolation of terrorist groups: Don’t take part in healthcare measures so no chance of creating herd immunity
How do we address social demographic issues in vaccination
- Education (about the facts)
- Campaigns
- Improved surveillance and vigilance
- Data in the public domain e.g. genome data
- Health partnerships between international agencies e.g. UNICEF/WHO and local health ministries
- Development of innovative funding initiatives
What are the requirements/ aims of a successful tissue and organ transplant
- transplants have to be physiologically viable
- the process should not harm the recipient
- transplant should not be rejected by the recipient’s immune system. This is done by giving immunosuppressive drugs to suppress the immune system, and HLA matching.
- adequate blood supply (to limit ischameia) to avoid inflammation
Difference between hyperacute, acute and chronic rejection during transplantation (type of hypersensitive, how it is caused, give examples)
- Hyperacute: immediate onset, type II hypersenstivity, caused by pre-existing antibodies on cell surface binding to the graft (non-self HLA) Causes vascular damage. Eg. in pregnancy, multiple blood transfusions, previous transplants.
- Acute rejection: type IV hypersensitivity. Mediated by T cells attacking alloantigens/ the transplant. Eg. kidney transplant, bone marrow transplant.
- Chronic: type III hypersensitivity. Reaction between antibodies and HLA recruits monocytes and neutrophils and allograft specific T cells
How is transplant rejection avoided
- Matching HLA antigens
- Immunosupressive drugs before and after surgery
-Otherwise causes graft-versus host disease
What are alloantigens/ alloreactions, and autoantigens/ autoreactions
- Alloantigens: someone else’s antigens, not your own. Alloreaction is an immune response to alloantigens
- Autoantigens: your own antigens. Immune response to own antigens