Section 4: Vaccines

Who developed the first vaccine and against what?

Jenner in 1796; vaccinia (cowpox) for smallpox.

What was variolation?

Using smallpox patient material to induce immunity; often caused severe disease.

List 5 requirements for a successful vaccine.

• Readily available

• inexpensive

• stable formulation

• safe with low side effects

• provides protection without causing disease

What are killed/inactivated vaccines? Examples?

Organism cannot replicate but antigens remain; rabies, hepatitis A, influenza.

What are live attenuated vaccines? Examples?

Organism modified to mimic natural infection without causing disease; smallpox, MMR, varicella.

What are subunit vaccines?

Use only specific antigenic components (e.g., capsules of pneumococcus, surface protein of anthrax).

What is a toxoid vaccine? Examples?

Detoxified bacterial toxin; diphtheria, tetanus.

How do DNA/RNA vaccines work?

Microbial DNA/RNA inserted into a plasmid; human cells take it up and produce proteins that elicit an immune response.

What is an advantage of RNA over DNA vaccines?

No risk of DNA integration into host genome; RNA only needs to reach cytoplasm.

Name two cancers linked to infectious agents that vaccines may protect against.

HPV → cervical cancer; HBV → HCC (liver cancer).

What is herd immunity?

Majority of population is immune, protecting the minority who are not immune; pathogen cannot easily spread.

What happens if too many people are not vaccinated?

Herd immunity decreases; entire population at risk; bioterrorism tactics can arise.