Vaccines

Question 1

What is the ultimate goal of vaccines?

Answer 1

To produce similar immune protection to that seen after natural infection but without causing disease

To generate long-lasting immunity (memory)

Question 2

Immunologic memory allows

Answer 2

Rapid recognition and response to infection

Prevention of disease or reduction of complications of a disease

Question 3

Live attenuated vaccines

Answer 3

Pathogens weakened under laboratory conditions - but still a virus, still able to infect and replicate

Long-lasting immune response, often after 1 -2 doses

Can occassionally cause symptoms of disease - mild form of diseases; more severe illness in people with immune problems –> often contraindicated or should not be given to immunocompromised individuals

Question 4

Currently there are live attenuated vaccines for….

Answer 4

Viral diseases: MMR, Chickenpox, Oral polio vaccine, intranasal Flu vaccine, Monkeypox/smallpox vaccine, Yellow fever vaccine

Bacille Calmette-Guérin - Attenuated mycobacterial vaccine for TB

Question 5

Inactivated vaccines

Answer 5

Pathogen is inactivated (by chemical process or heat)

Cannot cause disease, but often causes unspecific symptoms due to the immune response (pain, fever, headaches, body aches)

Usually multiple doses required (0, 1 month, 6-12 months)

Question 6

Currently there are inactivated vaccines for….

Answer 6

Viral diseases: Influenza vaccine (shots) and inactivated Polio vaccine (IPV)

Bacterial diseases: Cholera vaccine (inactivated and attenuated available)

Question 7

Inactivated toxins/toxoids

Answer 7

Toxin inactivated by chemical process or heat

Cannot cause disease

Usually multiple doses required

Question 8

Currently there are inactivated toxins for….

Answer 8

Tetanus (bacterial, Clostridium tetani)

Diptheria (bacterial, Corynebacterium diptheriae)

Question 9

Subunit/recombinant vaccines

Answer 9

Part of pathogen produced in lab by genetic recombination (cloning)

Can not cause disease

Usually multiple doses required

Question 10

Currently there are subunit/recombinant vaccines for….

Answer 10

Hep B vaccines

Question 11

Viral vector vaccines

Answer 11

Viral vector serves as vehicle to introduce part of DNA into host

Cannot cause disease

Host cells produce antigen

Concern: Pre-existing immunity against viral vector could lead to reduced efficacy of vaccine

Question 12

Currently there are viral vector vaccines for….

Answer 12

Some COVID vaccines (Janssen/J&J, AstraZeneca)

Experimental vaccines against ebola, zika, etc

Question 13

mRNA vaccines

Answer 13

mRNA encoding for part of pathogen is introduced into host - use lipid nanoparticles to protect mRNA and facillitate cell entry

Host cells produce antigen

Advantage: quick turn around from sequence identification to vaccine candidate

Challenges: Limited long-term exposure; Complicated manufacturing process; Some require storage at low temps

Question 14

Currently there are mRNA vaccines for….

Answer 14

Several COVID vaccines (Moderna, Pfizer)

Many different vaccines based on this principle now in the pipelines of many companies (flu, RSV)

Question 15

Components of Vaccine

Answer 15

Active component
&
+/- Adjuvant: often for inactivated/recombinant vaccines; help to enhance immune response/saving on amount of antigen; often aluminum based; newer ones based on CpG motif or plant saponins
&
Stabilizers/preservatives

mRNA vaccines use lipid nanoparticles to protect mRNA and facillitate cell entry