vaccines case Flashcards
what is meant by individual protection?
- Most countries have recommended routine vaccinations for their citizens
- Vaccination’s primary purpose is to protect the individual from infectious diseases that can cause significant harm
what is meant by community protection?
- Vaccinated individuals are less threat to others, disease can’t spread so much, reduces outbreaks
- If enough members of the population are vaccinated, you can eradicate the disease completely from that community
- This is called ‘herd immunity’ (aka population or community immunity). Protects the wider populations and less outbreaks within communities
what is small pox?
- Variola virus, highly contagious, caused plagues for centuries
- Blistering rash, blindness, arthritis
- Mortality 30-50% from variola major strain
- Since 900s in Eastern Asia ‘variolation’ was practised using smallpox scabs. Try to inoculate them by trying to put the virus under the skin or up the nose
- Not introduced in the West until 1700s
what is cow pox?
- Vaccinia virus, related to smallpox but causes milder infections (orthopoxvirus family)
- Dr Edward Jenner - noted dairy milkmaids contracted cowpox but not smallpox
- Inoculated a boy with cowpox, once mild infection cleared, he later inoculated him with smallpox twice – no reaction
WHO small pox eradication programme
World Health Organization, 8 May 1980
• Eradicated worldwide
• Return of the virus is unlikely
what are the problems with vaccination programmes?
can’t vaccinate everyone against every infectious disease.
what are the Joint Committee on Vaccination and Immunisation (JCVI)
- Specialist branch of Public Health England
- Responsible for monitoring and updating the vaccination schedule
- Make recommendations to government about all matters relating to vaccination
- Publish and update ‘The Green Book’
what is the NHS schedule
- Groups are targeted according to susceptibility and risk
- Babies at 2,3 and 4 months old need a range including: diphtheria, tetanus, pertussis, polio, Haemophilus influenzae type b, hepatitis B pneumococcus, rotavirus, meningitis b
what are the factors in deciding who gets a vaccination?
• The JCVI take many things into account when deciding, they relate to:
– The susceptible populations
– The diseases themselves e.g. HIV vaccine
– Pharmaceutical issues and the vaccine products
the factors in a population in deciding if gets vaccine
- Age – babies lack immunity, older people’s immunity declines over time
- Risk category – some people more at risk of serious illness than others e.g flu in pregnant women, people with co-morbidities
- Social changes – children starting school, or young adults starting university
- Public/media campaigns/new research
how does disease determine who gets a vaccine
- Prevalence of organisms and environmental factors e.g. flu in the UK
- Sudden outbreaks of a disease
- Desire to increase herd immunity
- Prevention of other risks related to the diseases e.g. more serious complications
how does pharmaceutical determine who gets a vaccine • Costs of mass manufacturing versus effectiveness of vaccine programme
• Antigenic drift or shift meaning new strains become prevalent
• If vaccine product is able to be produced – none so far for HIV, malaria: world’s first 2018
• Sometimes need to produce a vaccine quickly due to sudden pandemics…like COVID-19
what are risk associated with vaccines
- Mild illness, fever and rashes
- Pain, redness, swelling, tenderness at injection site
- Vaccine failure, insufficient immune response
- Small anaphylaxis risk – MHRA data suggests incidence of 1 per million doses approx
- Can be related to excipients or antigen e.g. ovalbumin (relevant in those with egg allergy)
what are the benefits associated with vaccines
- Saves lives
- Herd immunity benefits for those who can’t be vaccinated or are more vulnerable e.g. infants, elderly, pregnant women, immunosuppressed
- Eliminates the disease in some cases
- Easier, safer, a lot more convenient than contracting the disease and having to treat it
what is the global situation on vaccines
- WHO monitors vaccination use globally
- Schedules vary, may include vaccines for diseases specific to the geographical area
- Access to vaccination is a health inequality problem in some parts of the world
what is meant by immunity?
• Immunity = ability of the human body to protect itself from infectious disease
• Two main groups of defence mechanisms in the body :-
1. INNATE (non-specific, non-adaptive) mechanisms
2. ACQUIRED (specific, adaptive) mechanisms
how does the innate mechanism of immune defence work?
blocks infection by utilising barriers of entry eg skin, tears, mucus, stomach acid
how does the adaptive immune defence system work?
if the innate defence fails to work, it destroys invaders such as cellular factors, natural killer cells, phagocytic cells and soluble mediators. if that fails this triggers the adaptive immune system (APCs with induce antigen specific fragments in MHC activate t-cells and b- cells to control infection and produce memory cells
give examples of passive and active naturally acquired immunity ?
active- infection contact with pathogen
passive- antibodies passed from the mother to the baby through breastfeeding
give examples of active and passive artificially acquired immunity
active - vaccine- dead or attenuated pathogens
passive -injections of immune serum (gamma globulin)
what is meany by acquired immunity
• Acquired immunity usually specific to a single organism or group of closely related organisms (share common ANTIGENS – ie Cowpox/Smallpox) because you have contact with the pathogen
what is meant by active acquired immunity?
- Produced by individual’s own immune system - usually long-lasting
- Involves CELLULAR RESPONSES (“cell-mediated”), HUMORAL RESPONSES (“antibody mediated”) or a combination of both acting on the infecting organism
- Can be acquired by NATURAL DISEASE or by VACCINATION
- Vaccines provide immunity similar to that provided by the natural infection, but without the risk from the disease or its complications
how does the adaptive immune system work CD4 lineage ?
antigen presenting cells sees antigen
which chops it up and present it as peptides with MHC11 to naive CD4+ t-helper cells
which becomes effectors t- cells of 4 basic types
how does the adaptive immune system work for CD8 lineage?
antigen presenting cells (usually dendritic cells) see antigen (usually virus)
chops it up and present it peptide with MHC1 to naive CD8 cells
which become cytotoxic t -cells
which produce cytotoxins or triggers apoptosis of the target cells
to continue cytotoxic t- cells production and create memory cells. antigen presenting cells must interact with activated CD4 t- cells