vaccines

What is active immunity?

Immunity from your own immune response (infection or vaccination) → memory formed

What is passive immunity?

Transfer of preformed antibodies (e.g., maternal IgG, IVIG) → no memory

What are live attenuated vaccines

Weakened organisms that replicate and induce strong immunity

Key features of live attenuated vaccines?

Strong, long-lasting immunity

Induce cellular + humoral response

Contraindicated in immunocompromised & pregnancy

Examples of live attenuated vaccines?

MMR

Varicella (chickenpox)

Zoster (shingles)

Sabin oral polio

Vaccinia (smallpox)

What are inactivated (killed) vaccines?

Organisms that cannot replicate

Key features of inactivated vaccines?

Safer (can give to immunocompromised)

Weaker immune response

Require boosters

Examples of inactivated vaccines?

Influenza (injection)

Salk polio (IPV)

Rabies

What are subunit vaccines?

Contain specific antigen pieces (not whole organism)

What are toxoid vaccines?

Inactivated toxins (formalin-treated)

Example of toxoid vaccine?

DTaP (diphtheria, tetanus)

What is a pure polysaccharide vaccine?

T-independent response

No memory

Poor in children <2 years

What is a conjugate vaccine?

Polysaccharide linked to protein

Becomes T-dependent → memory formed

Examples of conjugate vaccines?

Haemophilus influenzae type B (Hib)

Neisseria meningitidis

Streptococcus pneumoniae (Prevnar)

What are recombinant vaccines?

Genetically engineered antigen proteins

Examples of recombinant vaccines?

HPV

Hepatitis B

What is an adjuvant?

Substance that enhances immune response

Mechanism of adjuvants?

Stimulate innate immunity

Increase antigen presentation

What is herd immunity?

Protection of unvaccinated individuals when enough of the population is immune

Why is herd immunity important?

Protects immunocompromised individuals

Limits spread of infection

Live vaccines

DON’T give in immunocompromised

Conjugate

T-dependent = memory

Polysaccharide alone

= weak in kids

Toxoid

= toxin neutralization

Recombinant

safe, specific antigens