immunisation Flashcards
lecture 11
What are the characteristics of passive immunity?
Short-lived (half-life of IgG about 3 weeks)
Hypogammaglobulinaemia in infants as maternal IgG declines
IVIgG every 2-4 weeks for immunodeficiency to maintain protective levels
Tetanus antitoxin
What are the characteristics of active immunity?
Exploits “immunological memory”
Secondary vs. primary response:
-Faster to develop
-Greater in magnitude
-May be qualitatively better (e.g., higher affinity antibody)
How does herd immunity work to protect both the individual and the population?
Individual Protection: Immunisation protects the individual from infection.
Population Protection: If a majority of the population is immune, the spread of the disease declines, leading to protection of the community (herd immunity).
What are some important facts about measles?
A highly contagious viral disease, patients develop a rash and a fever
In 2022, 136,000 people died
Serious complications can occur:
Ear infection, which can lead to hearing loss
Pneumonia, especially in young children
Sub-acute sclerosing panencephalitis (SSPE), a rare but fatal complication involving the CNS
What are the historical milestones and requirements for herd immunity against measles?
1st vaccine in 1963
MMR vaccine in 1988
Need 83-94% of the population immune to prevent outbreaks
1998 paper from Wakefield and colleagues linked MMR vaccine to autism
The paper was retracted but resulted in a decline in vaccine uptake and outbreaks
What are the requirements for an effective vaccine?
Safe
High level of protection
Long-lasting protection
Right type of response (local or systemic, antibody or cell-mediated immunity)
Low cost
Stable
Easy to administer
Minimal side effects
What are the different types of vaccines?
**Inactivated **(dead) organisms (e.g., Salk polio vaccine)
**Attenuated **(live but virulence disabled) organisms (e.g., Yellow fever, MMR)
**BCG **vaccine containing Mycobacterium bovis strain
Subunit vaccines - protein fragments (e.g., Hepatitis B)
**Toxoid **- bacterial toxin (e.g., Tetanus)
**Conjugate vaccines **(e.g., Streptococcus pneumoniae + diphtheria)
What are the key facts about polio?
Caused by an enterovirus, spread through the fecal-oral route
Mainly affects children under 5
1/200 cases result in paralysis
Member of the Picornaviridae family:** positive-sense RNA**, translated into a large polypeptide cleaved post-translation
Most infections are subclinical; a small number have flu-like symptoms
3 strains causing symptoms
What are subunit vaccines and toxoid vaccines?
Subunit vaccines use isolated antigens (e.g., Hepatitis B)
Tetanus toxoid: inactivated form of a protein exotoxin
What are conjugate vaccines and their benefits?
Conjugate vaccines allow T cell help for polysaccharide conjugated to protein
Converts** thymus-independent polysaccharide antigen to a thymus-dependent form**
Young children can respond
What is reverse vaccinology?
Whole genome screening to identify proteins for vaccines
Used to develop a vaccine against Neisseria meningitidis group B
: What are adjuvants and how do they enhance immune responses?
A substance administered with an antigen to promote immune response
Provide a depot
Immunostimulatory properties
Examples: Alum, MF59, AS03, AS04
What are some recent additions to the vaccination schedule?
MenB (Sept 2015 for babies)
MenACWY (2015 for teenagers)
Influenza (2003 nasal spray for children)
Shingles (2006 for over 70s)
RSV (2024 for late pregnancy and 75-79 year olds)
What changes occur in antibodies during successive immune responses?
Faster development
Greater magnitude
Higher affinity
What is the classification and transmission route of the polio virus?
Caused by an enterovirus
Spread through the fecal-oral route
What is a subunit vaccine and give an example?
Uses isolated antigens
Example: Hepatitis B surface antigen
How do conjugate vaccines enhance the immune response in young children?
Converts thymus-independent polysaccharide antigen to a thymus-dependent form
Young children can respond due to T cell help
What is reverse vaccinology and how was it used for Neisseria meningitidis group B?
Whole genome screening to identify vaccine proteins
Developed a 4-component vaccine through gene prediction and immunisation trials
What is the role of adjuvants in vaccines?
Substances administered with antigens to enhance the immune response
Examples include Alum, MF59, AS03, and AS04
What are some newer adjuvants used in clinical vaccines and their specifics?
MF59: Squalene-based, used in flu vaccines since 1997
AS03: Includes squalene and vitamin E, used in H1N1 flu vaccine
AS04: Alum plus monophosphoryl lipid A, used in HBV and HPV vaccines
What are inactivated (dead) vaccines and give an example?
Uses killed organisms to induce immunity
Example: Salk polio vaccine
What are attenuated (live) vaccines and give an example?
Uses live organisms with disabled virulence to induce immunity
Examples: MMR (measles, mumps, and rubella), Sabin polio vaccine
What does the BCG vaccine contain and what does it target?
Contains** Mycobacterium bovis strain**
Used to protect against tuberculosis (TB)
What are subunit vaccines and give an example?
**Uses protein fragments from the pathogen to induce immunity
Example: Hepatitis B vaccine
