Covid and mRNA vaccines Term 1 Flashcards
By what means is covid-19 virus transmitted?
Transmission by contact
-Transmission by droplets
-Airborne/aerosol transmission
Describe, in detail, how covid-19 is transmitted via contact.
-Direct-close, physical contact with the infectious individual
.Indirect-touching an object or surface that have been contaminated by infected person when people with the virus sneeze, cough or touch surfaces, they may leave infected droplets on these surfaces
Describe, in detail, how covid-19 is transmitted by droplets
tiny droplets of moisture containing pathogenic organisms are emitted when infected individual breathes, talks, sneezes, or coughs. These drops can be inhaled by others or ingested via food/utensils contaminated by droplets
Describe, in detail, how covid-19 is transmitted in terms of being airborne/aerosol
moisture in exhaled droplets evaporate after infected individual breathes, talks, sneezes, or coughs. Viruses remains viable, suspended in the air for long periods and can be dispersed in air currents infected others when inhaled
Describe the body’s natural immune response to viruses. What does it aid? What are it’s two processes?
Homeostatic mechanism triggered by entrance of foreign substances into body. Helps deal with invasion and restore internal environments to normal condition.
- antibody-mediated immunity (B cells)
-cell-mediated response (T cells)
Describe the process of antibody mediated immunity
Works against before entrance. Production of antibodies by B cells which circulate body and attack invading antigens
1.APC recognise, engulf, and digest pathogens displaying antigen on their surface
2.APC present antigen to specific B cells and T helpers
3.B cell becomes ‘sensitised /activated, T helper cells releases cytokines that activate more B cells
4.activated B cells increase size + divide, producing clones
5.most B cells become plasma cells that secrete antibodies to circulate blood, lymph + extracellular fluid
6.antibodies combine w/specific antigens to form antigen-antibody complex and destroy/inactivate non-self-antigens
7.remaining clones become memory cells that remain in lymphoid tissue allowing more rapid response to infection
Describe the process of cell mediated immunity
Works post-infection. Formation of special lymphocytes (T cells) that destroy invading cells
1.APC recognises, engulf + digest pathogen, displaying antigen on surface
2. APC present antigen to specific T cells
3. cytokines (released by t helper cells)stimulate T-cells to form clones after being sensitised, enlarging and dividing
4. most become Helper T-cells or Killer T-cells which migrate to infection site
5. Killer T-cells attached and destroy antigen by releasing cytotoxins that destroy membrane
6. Helper T-cells secrete substance that attracts more macrophages/increase macrophage activity
7. other clones=memory cells that remain in lymphoid tissue
9. Suppressor T cells derived from Killer T-cells secrete cytokines to signal lymphocytes to reduce activity to slow down immune response inhibiting B and T cells
What is an mRNA vaccine? How do they work?
Enters muscle cells and use them to make protein that unrecognised by the body=triggers an immune response following infection.
Introduces a piece of mRNA that corresponds to a viral protein, usually a small piece found on the virus’s outer membrane. By using this mRNA, cells can produce the viral protein recognised by the immune system. This causes production of antibodies as a response.
Define an example of a covid-19 vaccine that is an mRNA vaccine
Pfizer-BioNTech and Moderna COVID-19 vaccines are bivalent mRNA vaccines as they both contain a component of the original virus strain as well as from the strain caused by omicron variant
What is a protein sub-unit vaccine? How do they work?
Vaccine utilising fragments of protein from the disease-causing virus to trigger protective immunity against it. When the immune system encounters the protein fragment, it produces antibodies against it, preventing future infections.
Define an example of a covid-19 vaccine that is a protein sub-unit vaccine
Novavax is a protein-based vaccine. This type of vaccine contains part of the coronavirus spike protein.
Explain why masks are needed as a prevention tactic i.e. what do they prevent? How?
Prevent- airborne transmission as well as transmission through droplets.
Protective barrier covering the mouth + nose prevent inhalation of tiny droplets of moisture containing virus emitted when infected individuals breathe, talk, sneeze, or cough. Also prevents inhalation of moisture in infected exhaled droplets that remain viable, suspended in the air for long periods of time.
Explain why vaccines are needed as a prevention tactic i.e. what do they prevent? How?
allow for immunity by artificially introducing pathogens to individuals, allowing the body to develop immunity to the virus.
Decreases risk of future infection/susceptibility as well as increasing the populations immunity due to the prevention of transmission at the lack of infection in vaccinated individuals
Explain why isolation periods are needed as a prevention tactic i.e. what do they prevent? How?
prevent all types of transmission (contact, airborne, and droplets)
if individual is kept in an isolated environment, it is almost impossible for an unaffected individual to be infected.
the possibility of direct/indirect contact that may spread the virus has been made non-existent. As well as this, any droplets of moisture exhaled by the sick individual will no be inhaled by others whilst the infected patient is kept in a separate
