Vaccines Flashcards
What is a vaccine
A suspension of antigens to induce artificial active immunity
What are the two main types of vaccine
Live attenuated and Inactivated
How do vaccines produce long - term immunity
They cause memory cells to be created. When reencountering an antigen, the body then produces antibodies, in a faster, stronger secondary response
What is artificial active immunity
A specific immune response where antibodies are released by plasma cells
How effective are vaccines
Most are effective with one vaccination giving a lifetimes protection (less effective ones require booster)
How harmful are vaccines
Generally harmless - do not cause the disease they protect against because the pathogen is killed by the primary immune response
How can someone have a poor response to a vaccine
If they are malnourished and cannot produce the antibodies proteins or their immune system may be defective
How can antigenic variation cause an issue with vaccines
The variation in the antigens of pathogens causes the vaccines to not trigger an immune response or diseases caused by eukaryotes e.g. malaria have too many antigens
How can antigenic concealment cause an issue with vaccines
Pathogens ‘hide’ from the immune system by living inside cells or when the pathogen coats in host proteins or by parasitising immune cells
who discovered the principles underpinning vaccinations and when
Edward Jenner in the 1700s when he developed the smallpox vaccine
How do live attenuated vaccines work
These contain whole pathogens, these weakened pathogens multiply slowly, the body recognises the antigens and triggers the primary immune response, these vaccines often produce a longer - lasting immune response
How do inactivated vaccines work
Contain whole pathogens that have been killed or small parts of pathogens. However, these vaccines don’t trigger a strong or long lasting immune response (booster doses often required).
Why may some people have allergic reactions or local reactions to vaccines
Adjuvants (e.g. aluminium salts) may be conjugated (joined) to the subunit of the pathogen to strengthen and lengthen the immune response
When does herd immunity arise
When a sufficiently large proportion of the population has been vaccinated
What does herd immunity do
Makes it difficult for a pathogen to spread within a population
How do those who are not immunised stay protected using herd immunity
they are unlikely to contract the disease the population is vaccinated against as levels of disease are so low
Why is herd immunity important
allows for individuals who are unable to be vaccinated to be protected
Do proportions of population that need to be vaccinated to achieve herd immunity vary between different diseases
Yes
How does eradicating disease present a challenge
Some pathogens are complicated and present with disease processes that aren’t straight forward, so a vaccine could not be developed. Diseases that can be eradicated and have a vaccine, haven’t been because too few people have had the vaccine.
What economical reasons make eradicating disease challenging
Unstable political situations. Lack of public health facilities.
Has small pox been eradicated
yes
What is smallpox
A highly contagious disease caused by a virus that exists in two forms.
What are the two forms of smallpox and which is the worst
Variola Minor and Variola Major, the latter being the worst with a death rate of 12-30%
How was smallpox transmitted
Direct contact
Symptoms of smallpox
Red pus filled spots over entire body
what was aftermath of smallpox
people were disfigured from scabs and it also affected the eyes resulting in permanent blindness.
When did the WHO begin their eradication programme against smallpox
1967
What did the WHO’s eradication programme focus on
Vaccination - Aim to vaccinate more than 80% of populations at risk. If a case of smallpox was reported ring vaccination would occur. Surveillance - Neighbours would watch for signs of smallpox
What is ring vaccination
Where everyone in the household with a reported case, the surrounding 30 households, relatives and anyone who had contact would get vaccinated.
What was the success of the eradication of smallpox attributed to
The virus was stable (did not mutate, antigens stayed the same, same vaccine could be used), the vaccine could be transported without becoming unviable and the symptoms made it easy to identify.
