4.Lecture_Immunization

What is immunization?

The process of inducing or providing protection against an infectious disease.

How do active and passive immunization differ?

Active immunity triggers the recipient's own immune response and memory; passive immunity supplies ready-made antibodies for rapid, temporary protection.

What is natural active immunity?

Immunity acquired following a symptomatic or asymptomatic infection.

What is artificial active immunity?

Immunity induced by vaccination, often with booster doses to sustain protection.

What is the immunological basis of lasting active immunity?

Antigen-specific B and T lymphocyte activation and formation of memory cells.

What is natural passive immunity in a newborn?

Transfer of maternal antibodies through the placenta, giving temporary protection during early infancy.

What is artificial passive immunity?

Administration of preformed antibodies or immunoglobulin for immediate but short-lived protection.

What are homologous versus heterologous antibody preparations?

Homologous preparations are derived from humans; heterologous preparations come from animal sources (lecture terminology).

What is herd or collective immunity?

Reduced pathogen transmission when enough people are immune, indirectly protecting susceptible individuals.

Why are herd-immunity thresholds disease-specific?

They depend on pathogen transmissibility and other epidemiological characteristics.

What herd-immunity levels does the lecture estimate?

Measles around 83–95%; polio 80–86%; diphtheria over 85%; mumps 75–86% (illustrative estimates).

What happens when vaccination coverage falls substantially?

Previously controlled infections can reappear and cause outbreaks affecting vulnerable people.

What is the primary immune response?

The first antigen exposure induces antibodies after a delay and establishes immunological memory.

What primary-response delay does the lecture describe?

Approximately 3–14 days before antibodies appear.

How is a secondary immune response different?

It is faster (lecture: about 2–3 days), stronger, longer-lasting, and produces higher-affinity antibodies.

Why are booster vaccinations given?

To reactivate immune memory and restore or strengthen protection.

Who was Edward Jenner and what was his contribution?

He pioneered cowpox-based vaccination against smallpox in 1796.

What was Louis Pasteur's contribution to vaccination?

He developed early laboratory vaccine methods and administered an experimental rabies vaccine in 1885.

What are the main types of vaccines by preparation?

Live attenuated, inactivated, subunit/fractional, toxoid, recombinant, and mRNA-based vaccines.

What is a live attenuated vaccine?

A vaccine with a live organism whose virulence has been reduced while maintaining immunogenicity.

Why do live attenuated vaccines often produce strong immunity?

They mimic natural infection and stimulate humoral and cellular responses and durable immune memory.

Which vaccines are examples of live attenuated vaccines?

MMR, varicella, rotavirus, oral polio, intranasal influenza, yellow fever, and BCG.

What are major restrictions on live vaccines?

They are generally contraindicated in significant immunosuppression and many are contraindicated during pregnancy.

What are the main disadvantages of live attenuated vaccines?

Cold-chain demands, interference from passive antibodies, and possible interference between closely spaced injectable live vaccines.

What is an inactivated vaccine?

A vaccine containing microorganisms rendered non-replicating by chemical or physical methods.

How do inactivated vaccines differ from live vaccines immunologically?

They chiefly elicit antibody responses, cannot replicate, and often require multiple doses and boosters.

Which are examples of inactivated whole-organism vaccines?

Inactivated polio (IPV), hepatitis A, inactivated influenza, rabies, and some whole-cell bacterial vaccines.

What is a subunit or fractional vaccine?

A vaccine that contains selected antigenic components without the entire infectious pathogen.

Why are plain polysaccharide vaccines less effective in infants younger than two years?

They induce mostly T-cell-independent antibody responses and little long-lasting memory.

What is a conjugate vaccine?

A bacterial polysaccharide linked to a carrier protein, producing T-cell-dependent responses and better immunity in young children.

Which bacteria are targeted by major conjugate vaccines?

Haemophilus influenzae type b, Streptococcus pneumoniae, and Neisseria meningitidis.

What are toxoid vaccines?

Vaccines made from inactivated bacterial toxins that remain antigenic; tetanus and diphtheria are examples.

Why are boosters often necessary with toxoid and inactivated vaccines?

Vaccine-induced antibody concentrations may decline with time.

What is a recombinant vaccine?

A vaccine produced using recombinant DNA/protein-expression methods, e.g., hepatitis B or HPV.

How do mRNA vaccines work?

Host cells translate the administered mRNA into an antigen, triggering antigen-specific immune responses.

What is a monovalent vaccine?

A vaccine with one antigen or directed against one target.

What is a polyvalent or combination vaccine?

A preparation containing multiple antigens, such as DTaP combinations or MMR, that reduces injection and visit burden.

Which vaccine components directly support immunogenicity?

Antigens and, where used, adjuvants that enhance immune response.

What are preservatives and stabilizers used for in vaccines?

To maintain product safety and stability during storage and use.

What materials can be involved in vaccine manufacture?

Cell culture systems, inactivating substances, and certain antibiotics.

What characteristics define an ideal vaccine?

Effective durable protection, safety, affordability, adequate supply, good shelf life, and manageable storage.

What are the main vaccine administration routes?

Oral, intranasal, percutaneous, intradermal, subcutaneous, and intramuscular.

Which vaccines are examples of oral, nasal, and intradermal administration?

Oral OPV, intranasal live influenza, and intradermal BCG.

What are examples of vaccines commonly administered intramuscularly?

Hepatitis B and many routine inactivated or combination vaccines, according to their product instructions.

What is universal vaccination?

Routine vaccination of the general eligible population according to a national schedule.

What is selective vaccination?

Vaccination targeted to risk groups, such as extra pneumococcal/meningococcal protection after splenectomy.

What is vaccination by individual indication?

Vaccination driven by specific travel, work, family, or medical exposure risks.

What must be checked immediately before vaccination?

Correct product for the patient, expiry and batch, vial appearance, and monitoring indicators when applicable.

What interval is recommended between two injectable live vaccines not administered simultaneously?

At least 28 days (four weeks); the second may need repeating if given too soon.

Is a special separation interval needed between most other vaccines?

No additional separation is generally necessary except for product-specific dose schedules.

Does an extended interval between vaccine doses require restarting the entire series?

No; continue the series without restarting merely because of delay.

Why must minimum recommended vaccine ages and dose intervals be respected?

Shorter intervals or younger administration may lead to inadequate immune responses.

How is vaccine safety studied before marketing approval?

Clinical phases assess safety, immune responses, effectiveness, and adverse events in increasing participant numbers.

What is the focus of phase I vaccine studies?

Initial safety, dose, and immune response in a small number of volunteers.

What is the focus of phase II vaccine studies?

Further safety, immunogenicity, and dosing in larger participant groups.

What is the focus of phase III vaccine trials?

Large-scale efficacy comparison and assessment of common and serious adverse effects.

What is phase IV vaccine monitoring?

Continued post-licensure surveillance for uncommon risks and real-world safety.

What is an adverse event following immunization (AEFI)?

Any unfavorable medical occurrence after vaccination; temporal association does not necessarily establish vaccine causation.

What categories of AEFI are described in the lecture?

Vaccine-related event, program/administration error, coincidental event, injection-related reaction, and unknown cause.

What are common local vaccine reactions?

Redness, warmth, swelling, itching, and pain at injection site, usually occurring within 24–48 hours and resolving in 1–2 days.

How can typical mild local vaccine reactions be managed?

Cold compresses and symptom relief/analgesia when needed.

What are common systemic post-vaccination reactions?

Short-lived fever, rash, headache, irritability, or other mild symptoms depending on the vaccine.

When can delayed systemic symptoms follow the first MMR vaccination?

About 7–14 days afterward, such as fever, rash, or lymph-node/salivary-gland symptoms (lecture).

Are prophylactic antipyretics routinely recommended before vaccination?

No; routine premedication is discouraged and does not reliably prevent febrile seizures.

What important immediate reaction requires emergency response after vaccination?

Anaphylaxis, which may develop within minutes to hours.

What is an important general reason not to repeat the same vaccine?

Previous severe anaphylaxis to that dose or a relevant vaccine component.

How does immunosuppression affect vaccine selection?

Significant immunosuppression generally contraindicates live vaccines; inactivated vaccines are usually safe but may work less effectively.

What are contraindications to rotavirus vaccine?

Severe combined immunodeficiency, previous intussusception, or anaphylaxis to a prior dose/component.

What serious event after pertussis vaccination may preclude further pertussis doses?

Encephalopathy within seven days without another identifiable cause.

Why might MMR/varicella vaccination be delayed after blood products or immunoglobulin?

Passive antibodies may blunt responses to these live vaccines; the interval depends on the product.

Do blood product transfusions routinely prevent administration of inactivated vaccines?

No; the lecture states interference is minimal or absent.

Which live vaccines does the lecture identify as minimally affected by blood derivatives?

Oral rotavirus, intranasal influenza, and BCG.

Are mild illness and antibiotic use usually contraindications to vaccination?

No, they are not general contraindications.

Are breastfeeding, prematurity, or multiple vaccines on the same day general contraindications?

No; these are not general reasons to withhold routine vaccines.

Is an unrelated allergy or family history of reactions a general vaccine contraindication?

No, unless the patient has a specific relevant serious allergy.

What systemic corticosteroid regimen does the lecture associate with withholding live vaccines?

Prolonged high-dose systemic prednisone, such as at least 2 mg/kg/day for more than 14 days (lecture example).

Are topical and inhaled corticosteroids automatically a contraindication?

No; the lecture distinguishes them from prolonged systemic immunosuppression.

What precautions are useful for intramuscular vaccination in coagulopathy?

Use appropriate hemostatic measures, a small appropriate needle, firm gentle pressure for about two minutes, and no massage.

Should medically stable preterm babies be vaccinated by chronological or corrected age?

Chronological age, generally following routine age recommendations for term infants.

Why should preterm babies receive routine vaccines even if antibody responses are somewhat lower?

Protective levels and memory are generally achieved and preterm infants have high infection risk.

When does the lecture suggest influenza vaccination in preterm infants?

From six months of chronological age during influenza season.

When is the hepatitis B birth dose given in the lecture's immunization calendar?

Within the first 24 hours of life.

When does the lecture's calendar give BCG?

On discharge from the maternity hospital, or within the first year according to the local schedule discussed.

What is in the hexavalent vaccine described by the lecture?

DTaP + Haemophilus influenzae type b + hepatitis B + IPV.

What is in the pentavalent vaccine described by the lecture?

DTaP + Haemophilus influenzae type b + IPV.

What RV5 rotavirus timing is given in the lecture's calendar?

Three doses, begin no later than 12 weeks, give each 4–10 weeks apart, finish by 32 weeks.

What pneumococcal vaccine schedule is described for ages 2–11 months?

Two initial doses plus one booster (local lecture schedule).

What pneumococcal catch-up schedule is described for ages 12–23 months?

Two doses separated by at least two months, no booster (local lecture schedule).

What pneumococcal catch-up schedule is described for ages 2–5 years?

One dose and no booster (local lecture schedule).

When is MMR administered in the lecture's calendar?

First dose at 12 months and second dose around six years/school entry.

When are the main childhood DTaP/polio booster doses in the lecture's schedule?

First revaccination at 18 months and another DTaP-IPV dose at about seven years.

Which later tetanus-containing boosters are described?

DT-IPV near the end of primary school and a tetanus-toxoid dose around age 18 years.

What HPV scheduling approach is described in the lecture?

Routine vaccination around or before 14 years; for girls starting after 15, a three-dose series spanning about six months (lecture-specific schedule).

What is immunization coverage (IC)?

Number vaccinated in a specified age group divided by the total number in that age group.

What immunization coverage goal is recommended in the lecture?

Aim for about 95% of eligible people, recognizing that population thresholds vary by disease.

What program measures improve vaccine coverage?

Reliable funding, reminders, monitoring systems, continuing public education, and clinician communication.

How should clinicians address vaccine hesitancy?

Listen to concerns, explain risks of delayed/non-vaccination, emphasize individual/community benefits, and offer trustworthy sources.