Week 4 lectures

What is a vaccine?

They are used to allow the body to produce adaptive responses to pathogens that they have not actually been infected with. This allows for the actual infectious stage to be skipped if we actually contract it and allow for a rapid response.

What is the purpose of herd immunity?

Herd immunity refers to the vaccination of a majority of eligible people. This will mean that the disease is harder to pass on in the population. This also protects the more vulnerable people that are not able to be vaccinated themselves.

What does the herd immunity threshold depend on?

Transmissibility of the disease.

What is transmissibility?

It is the ability of a pathogen to be passed from one person to another.

What is the basic reproduction number?

It is used to determine transmissibility - the average number of secondary cases that are caused as a result of a primary case.

What is the effective reproduction number?

It is the actual number of secondary cases that are caused as a result of a primary case. It excludes those that are immune.

How is the herd immunity threshold calculated?

1-1/R0

What is the typical herd immunity threshold in the UK for measles?

95%.

When was the first vaccination act brought in?

1853 - the smallpox vaccine was free and compulsory.

When was the first International Certificate of Vaccination introduced?

1944 - for smallpox. It increased compliance.

What are the main arguments against vaccination?

That they are ineffective and cause harm.

What is vaccine hesitancy?

A delay in accepting or partial/selective refusal of vaccines even though they are available. It is shaped by context, trust and circumstance.

What is antivaccination?

Opposition to vaccines because of ideological/conspirational/religious belief. They won’t change their mind when given information or easier access.

What is meant by under vaccination?

Where they are below the target coverage but it is typically as a result of barriers/cost/infrastructure/supply rather than hesitancy or refusal.

How can healthcare professionals discuss vaccines with hesitant parents?

Reassure about the safety to maintain public safety and explain that the risks of not vaccinating are much more significant compared to the risks associated with vaccination. Minor side effects. In case of allergic reactions we have the equipment to manage that.

Who needs to be vaccinated?

• Those that are at risk of suffering severe disease,

• Risk of infecting others,

• Risk of exposure to the disease,

• Age, health status and vaccination history,

• Risk factors,

• Cost.

What defines the specificity of the acquired immune response?

The receptors located on B and T cells. Antibodies and T cell receptors.

What is clonal selection?

When a specific antibody producing B cell is selected to undergo clonal expansion as it is specific and able to combat the antigens of a disease.

What is the benefit of acquired immunity?

It means that there are memory B and T cells so that a quick response can be generated upon secondary infection.

What is active immunisation?

It is a process which leads to a first infection with a pathogen is recognised as if it was a second infection - actively induces the acquired immune response.

What is passive immunisation?

Transfer of pre-made immunological mediators to generate an enhanced immunity.

Who do vaccinations protect?

The vaccinated individual and the population around them.

How can live vaccines be attenuated?

Naturally attenuated: related strains or species.

Artificially attenuated: random and designer.

What can the contents of a non-living vaccine be?

Killed whole organisms, antigenic components of the organism or DNA/RNA of the organism.

How can adjuvants enhance immunogenicity?

Inducing inflammation, providing microbial signals to boost innate immunity and provide a long lasting depot of antigen.

What type of virus is polio?

It is a positive single stranded RNA virus.

What type of virus is the SARS-CoV-2?

Positive, single-stranded RNA virus.

How does the SARS-CoV-2 virus infect?

The spike proteins binding to the ACE2 receptor.

What are the types of eukaryotic parasites?

Protozoa (unicellular), Helminths (multicellular eukaryotes) and anthropods.

What are considerations with parasite infections?

• There is parasite diversity - genetic variability,

• Life cycle within the host,

• Host-pathogen interactions - avoidance mechanisms, etc,

• Antigen load,

• Concomitant immunity,

• Pathology,

• Multiple infections,

• Immunocompromised.

What are features of ideal anti-parasite drugs?

• Selective toxicity to parasites,

• Target many species and life stages,

• Cost effective,

• Easy to administer/distribute,

• Unlikely to develop resistance.

What makes treating parasites difficult?

They are eukaryotic and share a lot of metabolic machinery with humans, antibacterials do not work on parasites and the therapeutic window might be very narrow.

What are anti-protozoal agents?

They target rapid proliferating, young, growing cells.

Nucleic acid synthesis, protein synthesis, specific metabolic pathways and detoxification mechanisms.

What are anti-helminthic agents?

They target non-proliferating adult organisms.

Neuromuscular coordination, carbohydrate metabolism and microtubular integrity.

What are the types of human malaria?

Plasmodium falciparum, vivax, ovale and malariae.

What are the 2 asexual replication stages in humans?

Liver stage and blood stage.

What are seen on blood films of those that are infected with malaria?

Rings and young trophozoites.

What 2 tests are needed for diagnosis of malaria?

Parasitological test (microscopy) and a rapid diagnostic test.

What symptoms does malaria have?

Fever, chills, sweats, headaches, nausea, vomiting, body aches and general malaise.

What are some complications of malaria?

Cerebeal malaria, acidosis or severe anemia.

What are malaria chemotherapy?

Quinolines, anti-folates and artemisinin compounds.