Immunity & Vaccines

Vocabulary flashcards covering key concepts of the immune system, vaccines, and therapeutic applications from the lecture notes.

Adaptive immunity

specific and delayed onset; memory

Adaptive immunity: t cells

helper and cytotoxic responses

Adaptive immunity: b cells

make antibodies

Adaptive immunity: cells

b lymphocytes, t lymphocytes, long term memory cells

Innate immunity: cells

neutrophils

macrophages

dendritic cells

NK cells

Innate immunity: barriers

skin

mucosa

Innate immunity

Non-specific and immediate, all about speed; complement proteins and cytokines

Functions of immune system

recognition of pathogens

response and memory

Vaccines: immune leverage

utilize adaptive immunity and memory cells

Vaccine

stimulates adaptive immunity, leads to memory

safely introduces antigens

does not cause disease

prevention, not treatment

Active immunity: definition

host immune system produces its own responses and memory

Active immunity: onset

slow (days to weeks)

Active immunity: duration

long-lasting (years to life)

Active immunity: memory cells?

yes

Active immunity: examples

natural infection- chickenpox

vaccines- MMR, Tdap

Passive immunity: definition

host receives ready-made antibodies

Passive immunity: onset

immediate (hours)

Passive immunity: duration

short-lived (weeks to months)

Passive immunity: memory cells?

no

Passive immunity: examples

maternal IgG, IVIG, antitoxin, monoclonal antibodies

Live-attenuated vaccine: definition

Weakened form of pathogen that can replicate; strong and long-lasting immunity

Live-attenuated vaccine: limitations

contraindicated in pregnancy and immunocompromised

small risk of reversion

Live-attenuated vaccine: examples

MMR

varicella

intranasal flu

yellow fever

Inactivated vaccine: definition

Whole pathogen inactivated, so cannot replicate; safe for most, no risk of infection

Inactivated vaccine: limitations

weaker immunity than live vaccines

often require boosters

Inactivated vaccine: examples

Hep A

polio (IPV)

rabies

Subunit/recombinant/polysaccharide vaccine: definition

Uses specific antigen fragments of pathogen; very safe, fewer side effects; targeted

Subunit/recombinant/polysaccharide vaccine: limitations

often less immunogenic

adjuvants or boosters needed

Subunit/recombinant/polysaccharide vaccine: examples

HPV

HBV

shingrix (RZV)

pneumococcal

Toxoid vaccine: definition

Inactivated bacterial toxin; protects against toxin-mediated release

Toxoid vaccine: limitations

immunity not directed against organism itself

boosters needed

Toxoid vaccine: examples

tetanus

diphtheria

mRNA vaccine: definition

Delivers mRNA coding for antigen, host cells make protein

mRNA vaccine: development

rapid development

strong response

NO pathogen needed

mRNA vaccine: limitations

requires cold storage

newer technology

ongoing safety monitoring

mRNA vaccine: examples

Pfizer-BioNTech & Moderna COVID-19

Viral vector vaccine: definition

harmless virus delivers antigen genes; elicits strong cellular and humoral immunity

Viral vector vaccine: limitations

pre-existing vector immunity may reduce efficacy

Viral vector vaccine: examples

J&J COVID-19

ebola vaccine

Conjugated vaccine: why used in children

infants under 2 don’t respond to plain polysaccharide antigens

conjugation tricks immune system into recognition by using a protein

Conjugated vaccine: clinical relevance

Hib conjugate vaccine virtually eliminated Hib meningitis in US children

Conjugated vaccine: definition

Polysaccharide antigen linked to a protein carrier

Conjugated vaccine: purpose

improve T cell response in infants and children under 2

creates stronger memory and longer lasting protection

Conjugated vaccine: examples

Haemophilus influenzae type b (Hib)

pneumococcal (PCV13)

meningococcal (MenACWY)

Conjugation

Linking a polysaccharide antigen to a protein carrier to recruit T-helper cell help.

Herd immunity: definition

Protection of non-immune individuals when a critical portion of the population is immune

Herd immunity: threshold

R₀ value varies by disease

Herd immunity: boosters

used to prevent waning immunity

Herd immunity threshold: measles

about 95%

Herd immunity threshold: pertussis

about 92-94%

Herd immunity threshold: influenza

about 70%

Herd immunity threshold: COVID-19 (early estimate)

about 70-85%

True contraindications

severe allergic reaction

immunocompromised patients

pregnancy

True contraindications: immunocompromised patients

avoid live vaccines

True contraindications: pregnancy

avoud live vaccines (MMR, varicella, intranasal flu)

Precautions

not absolute contraindications

moderate/severe acute illness

recent antibody-containing blood product

Precautions: acute illness

may delay vaccination

Precautions: recent antibody-containing blood product

can interfere with some vaccines

Not contraindications

common myths

mild illness, antibiotic use, family history of adverse reaction (unless known disposition)

Adverse Effects: common and expected

pain, redness, swelling at injection site; mild fever, fatigue, myalgias

usually resolves in 24-72 hours

Adverse Effects: rare and serious

anaphylaxis, febrile seizures, intussusception, Guillian-Barre syndrome

Adverse Effects: anaphylaxis

rare, but life threatening

Adverse Effects: febrile seizures

rare, usually self limited

Adverse Effects: intussusception

rotavirus vaccine

Adverse Effects: Guillian-Barre Syndrome

rare, sometimes after influenza vaccine

Safety Monitoring

VAERS

CDC & FDA continuously review for signals

VAERS

Vaccine Adverse Event Reporting System, a U.S. system for monitoring vaccine safety signals.

Special populations: infants and young children

immature immune systems required conjugated vaccines

multiple-dose series to build memory

Special populations: elderly (65+)

immune senescence require higher dose or adjuvanted vaccines

Special populations: pregnancy

safe and recommended- Tdap (3rd trimester), influenza

contraindicated- live vaccines (MMR, varicella, intranasal flu)

Special populations: immunocompromised patients

avoid live vaccines (people with chemo, rituximab, transplant, HIV with low CD4)

may need additional doses or timing adjustments

Why to distinguish contraindication from precaution

prevents unnecessary delays or missed opportunities; ensures safety while maximizing coverage

Monoclonal antibodies (mABs): definition

lab-engineered antibodies targeting specific antigens (precision medicine)

Monoclonal antibodies (mABs): production

produced by cloned B cells in the lab

Monoclonal antibodies (mABs): immunity

provide passive immunity (ready-made, no memory)

Monoclonal antibodies (mABs): clinical uses

oncology

autoimmune disease

allergy/asthma

infectious disease

Monoclonal antibodies (mABs): oncology use

used in lymphoma and breast cancer

Monoclonal antibodies (mABs): autoimmune use

used in Chron’s and rheumatoid arthritis

Monoclonal antibodies (mABs): infectious disease use

RSV in infants

COVID-19

Vaccines vs mABs

vaccines- active immunity, body builds memory

mABs- passive immunity, immediate and temporary

Why use mABs over vaccines

useful in high-risk patients who can’t mount their own immune response

immediate effect during active disease

Monoclonal antibodies (mABs): limitations

adverse effects

practical barriers

temporary protection (no memory)

access issues

Monoclonal antibodies (mABs): adverse effects

infusion reactions

hypersensitivity

infection risk

Monoclonal antibodies (mABs): practical barriers

high cost

IV/SC administration

required monitoring

Monoclonal antibodies (mABs): access issues

insurance approval

availability