7: vaccines

How does vaccination work?

Vaccination mobilizes the host immune system to prevent virus disease.

What happens during first infection?

Initial immune response peaks in a week or two.

What happens during protective immunity?

Titers decline to a low level.

What happens during immunological memory?

Years later, if reinfected, the immune system can respond more quickly with more specificity.

When was the first vaccine developed?

In 1796 by Jenner.

What was the first vaccine?

Smallpox vaccine.

What did Pasteur contribute to vaccines?

He discovered the rabies vaccine and introduced the term vaccination.

What happened in the 1930s?

Yellow fever and influenza vaccines were discovered.

What viruses have been nearly eradicated due to vaccines?

Polio and measles.

What is herd immunity?

Maintenance of a critical level of immunity in a population resulting in those who are not immunized being more protected.

When does virus spread stop?

When the probability of infection drops below a critical threshold.

How many people must be immune to prevent COVID-19 spread?

50-70%.

Is the critical threshold of immunization the same for every virus?

No, it is virus and population specific.

What is the critical threshold for smallpox?

80-85%.

What is the critical threshold for measles?

93-95%.

When is 76% of the population immune to measles?

When 80% of the population is immunized.

What is an active vaccine?

A vaccine that is instilling into the recipient a modified form of the pathogen, or material derived from it, that induces immunity to disease.

What kind of protection does an active vaccination give?

Long-term protection.

What is a passive vaccine?

A vaccine that is instilling the products of the immune response, antibodies or immune cells, into the recipient.

What kind of protection do passive vaccines give?

Short-term protection.

What are some examples of passive vaccines?

Rabies vaccine from immunoglobin harvested from people who have been vaccinated, and convalescent plasma and monoclonal antibodies for COVID-19.

What is a natural passive vaccine?

When a mother gives her baby some antibodies during gestation through the placenta.

When does a babies immune system develop?

Around 9 months.

What are the requirements of an effective vaccine?

Induction of an appropriate immune response, safety, protective immunity in the population, long-lasting protection, low cost, and genetic stability.

How are COVID-19 vaccines made?

DNA encoding the spike protein used to make mRNA in vitro which are packaged into lipid nanoparticles.

How do COVID-19 vaccines work?

Spike protein binds to a surface receptor and leads to fusion, and the added prolines to the spike protein sequence prevents fusion extern