COVID and vaccines

Question 1

vaccine contents

Answer 1

• antigen: tells the immune system the pathogen’s identity

- adjuvants: substances that alert the immune system to danger.

Question 2

live vaccines

Answer 2

• e.g. nasal flu shot
• contain a modified version of the pathogen that cannot cause disease because it has been modified to grow at temperatures other than 37°C or in cells that are not human
• however, the virus could mutate to become active again and cause vaccine-induced infection

Question 3

PAMPs

Answer 3

• pathogen associated molecular patterns
• component of live and inactivated vaccines
• they trigger our innate immune response

Question 4

why is a smaller dose better than a bigger dose for AstraZeneca?

Answer 4

-with a larger dose, the adenovirus vector is more detectable by the immune system, so the immune system attacks the adenovirus before it can enter a cell and release the genetic info for the spike protein -> less effective at creating antibodies and immunity

Question 5

Why might we not be able to use the adenovirus as a viral vector in the future?

Answer 5

• those who have been vaccinated with the AstraZeneca COVID19 vaccine may have developed antibodies against the adenovirus which can be remembered by B lymphocytes
• therefore, if we use this as a vector again, the immune system would quickly produce antibodies and kill the adenovirus, preventing the actual contents from being translated into the required antigen

Question 6

what makes COVID19 such a successful pathogen?

Answer 6

• it can mutate quickly

- people can be asymptomatic & so they can pass it without knowing -> increasing transmission

Question 7

Omicron

Answer 7

• there are around 50 mutations across the entire genome of the virus and more than 30 in the part that codes for its spike
• the receptor-binding domain (RBD) on the spike binds to the ACE2 receptor in the membrane of human cells
• The Beta variant has 3 mutations in the RBD, the Delta variant has 2, Omicron has 15

Question 8

which countries have made COVID vaccines compulsory?

Answer 8

-austria: due to extreme surge of cases
-indonesia: announced mandatory vaccination in February, with potential hefty fines for those who do not comply
-UK: Health and social care workers, need to provide evidence they have been fully vaccinated against COVID-19 in order to be deployed,
deadline for care home workers to be double jabbed was 11 November
-Italy and France have made vaccination mandatory for health workers

Question 9

immunity definition

Answer 9

Immunity is a complex biological system that can recognise and tolerate whatever belongs to the self, and to recognise and reject what is foreign (non-self)

Question 10

TACTIC Trial

Answer 10

• the complement system is one of the first systems triggered when the immune system spots a pathogen
• when activated, the system sets off a rapid chain of events that both alerts the rest of the immune system and also directly destroys cells
• excessive activity by the complement system is thought to be responsible for at least some of the severe organ damage seen in COVID-19
• This trial tests Ravulizumab that blocks an “on-switch” in the complement cascade
• immune cells ‘talk’ to each other using cytokines.
• The right amount of the right cytokines gives the best immune response – but too much of the wrong cytokines causes inflammation that can damage healthy cells and tissues (cytokine storm) and is thought to be another contributor to severe COVID-19 responses
• The trial also tests whether Baricitinib, a drug that is regularly used to ‘dial down’ excessive cytokines in people with rheumatoid arthritis, can effectively reduce the cytokine storm experienced by patients with severe COVID-19 symptoms.