Vaccination and population immunity

Question 1

Main role of immune system?

Answer 1

Protect from infections

Question 2

Why has the infectious diseases rate decreased?

Answer 2

Widespread antibiotics, immunisation, better sanitation and better nutrition helped to reduce infectious diseases.

Question 3

History of smallpox?

Answer 3

• First vaccination created for smallpox
• 30% mortality
• Caused by variola virus
• Symptoms: weals, systemic illness, scarring

Question 4

History of cowpox?

Answer 4

• Similar virus to smallpox
• Lower mortality than smallpox
• Immunity to cowpox protects against smallpox - Edward Jenner was the pioneer
• 1796 → Smallpox eradicated 1980

Question 5

History of chicken cholera?

Answer 5

• 1880
• Louis Pasteur → Looking at transmission of cholera in chickens.
• Culture of cholera bacteria was created and once given to chickens they would die …. But then realised that dead cholera bacteria was injected into the chicken and they didn’t die.
• Found that ‘killed’ vaccines would prevent them getting diseased from the ‘live’ bacteria.

Question 6

History of human cholera

Answer 6

• Vibrio Cholera
• Still endemic
• Jaume Ferran Clua 1885 - created a ‘killed’ vaccine for cholera
• ‘Wasting disease’ → systemic disease, intense diarrhoea, dehydration, extreme GI issues and if not treated can have serious consequences.

Question 7

History of tuberculosis

Answer 7

• Still relevant today
• Respiratory disease causing cavitated lesions in the lungs
• Albert Calmette and Camille Guerin tried to develop a vaccine for TB. They tried growing the bacteria but it started clumping together. They added ox-bile to reduce the clumping and it also reduced the virulence of TB
• Live attenuated vaccine BCG

Question 8

History of Hepatitis B

Answer 8

• 1965 Hepatitis B identified
• 1975 first vaccine
• Heat treated virus - instead of treating with ox bile/or ‘dead’ it is treated with heat to denature it
• 1982 managed to remove the DNA from Hep B
• DNA introduced into yeasts which produced the Sag (proteins for hep B virus)
• Known as recombinant HBSAg vaccine

Question 9

What was the controversy surrounding the MMR vaccine?

Answer 9

Development of autism followed by the MMR vaccination. 12 children, no controls, timelines given by parents. The doctor was being paid to help people in US to sue the manufacturer of MMR

Question 10

What is herd immunity and why is it needed?

Answer 10

• Protect clinically vulnerable
• Protect those who cannot be vaccinated
• Need most of the healthy population vaccinated
• Only for person-person spread (not tetanus as that is from a wound where bacteria has entered)

People who depend on herd immunity
- Immune compromised
- Chemotherapy
- HIV
- Newborn babies
- Elderly
- Other illnesses

Question 11

What things would you consider when designing a vaccine and can you give some examples?

Answer 11

What against?
- Antigen
- Whole/part organism → attenuated, heat-treated, live?
- DNA/RNA
- Evolution and changes in antigenicity

Adjuvants (material added to antigenic part of vaccine to empire immune system notices it)
- Increase magnitude of immune response
- Pathogen-associated molecular patterns (PAMPS)
- Aluminium salt

Delivery
- Nasal – first entry block for -respiratory diseases
- Oral
- Injection

Question 12

What are the challenges we face with vaccinations?

Answer 12

• Current and future pandemics
• New/old diseases
• Public opinion and information/misinformation