Immunization and Herd Immunity

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Questions and Answers

How does active immunity differ from passive immunity?

Active immunity is produced by an individual's own immune system and is long-lasting, while passive immunity is provided through the transfer of antibodies and is temporary.

What is the primary goal of immunization in the long term?

The primary goal of immunization in the long term is the eradication of disease from the world.

What is herd immunity and how does it protect individuals in a community?

Herd immunity, or community immunity, reduces the risk of infection among susceptible individuals by the presence of immune individuals, providing indirect protection.

In what ways can passive immunity be transferred?

Passive immunity can be transferred through maternal antibodies across the placenta, mother’s milk, blood transfusions, and blood products. Signup and view all the answers

What role do vaccines play in the immune system?

Vaccines stimulate the body's own immune system to create immunity against infectious diseases without the risk of severe complications from the disease. Signup and view all the answers

What is the primary difference between active and passive immunity?

Active immunity is developed through vaccination or infection, while passive immunity is provided through the transfer of antibodies. Signup and view all the answers

List two diseases that can be prevented through vaccination and one symptom associated with each.

Measles (high fever and rash) and Polio (muscle stiffness and paralysis). Signup and view all the answers

How do maternal antibodies provide passive immunity to infants?

Maternal antibodies are transferred to infants through the placenta during pregnancy and through breast milk after birth. Signup and view all the answers

Explain why vaccinations are considered essential for public health.

Vaccinations prevent the spread of infectious diseases and protect vulnerable populations, thereby reducing overall disease incidence. Signup and view all the answers

What is the rationale behind administering immunoglobulins?

Immunoglobulins provide immediate passive immunity by supplying ready-made antibodies to combat infections. Signup and view all the answers

What are two significant disadvantages of live attenuated vaccines?

They may cause mild clinical features of the disease and cannot be given to immunosuppressed or pregnant individuals. Signup and view all the answers

What is a key advantage of live attenuated vaccines compared to inactivated vaccines?

Live attenuated vaccines provide a potent immune response that is close to the optimal naturally acquired immune response. Signup and view all the answers

Name two examples of inactivated vaccines and their components.

Examples include IPV (whole dead organism) and Diphtheria (toxoids). Signup and view all the answers

Which vaccine is administered using an intradermal injection, and what is its purpose?

The BCG vaccine is administered intradermally to help prevent tuberculosis. Signup and view all the answers

Describe the site and the expected outcome of a successful BCG vaccination.

It is administered in the lateral aspect of the left upper arm, leading to a small local swelling that heals to form a flat scar. Signup and view all the answers

What is a crucial benefit of inactivated vaccines in terms of patient safety?

Inactivated vaccines cannot cause clinical infection and can be given to immunosuppressed or pregnant individuals. Signup and view all the answers

List two routes of administration for vaccines and provide an example for each.

Oral route for OPV and intramuscular route for MMR. Signup and view all the answers

What serious condition can prevent an individual from receiving vaccines?

A serious allergic reaction, such as anaphylaxis, after a previous vaccine dose can prevent vaccination. Signup and view all the answers

What happens during the immune response following a live attenuated vaccine, such as the OPV?

The vaccine stimulates an immune response similar to natural infection, leading to immunity. Signup and view all the answers

At what age is the first dose of the BCG vaccine administered in Oman?

The first dose of the BCG vaccine is administered at birth. Signup and view all the answers

What vaccines are given at 2 months of age in the Oman vaccination schedule?

At 2 months, the vaccines given are Hexa-1, PCV13-1, and Rota Vaccine-1. Signup and view all the answers

Which vaccinations are scheduled for 18 months of age in Oman?

At 18 months, MMR-2, OPV Booster, and HAV-1 are scheduled. Signup and view all the answers

What vaccinations are administered to children in Grade 1 in the Oman School Immunization schedule?

Children in Grade 1 receive DT and OPV vaccinations. Signup and view all the answers

What is the main difference in administration between OPV and IPV?

OPV is administered orally while IPV is given via injection. Signup and view all the answers

At what ages are the DTP vaccine doses administered in Oman?

The DTP vaccine is given at 2, 4, and 6 months of age. Signup and view all the answers

What are the side effects associated with the OPV?

OPV has been associated with rare cases of vaccine-associated paralytic poliomyelitis. Signup and view all the answers

How does the hepatitis B vaccination schedule differ for infants and older children?

Infants receive 4 doses of hepatitis B vaccine at 0, 2, 4, and 6 months, whereas older children typically follow a different schedule. Signup and view all the answers

What precautions are taken for newborns when the mother is HBeAg positive?

The newborn should receive both hepatitis B vaccine and hepatitis B immunoglobulin (Hep B IG) at birth. Signup and view all the answers

What is the route of administration for the varicella vaccine?

The varicella vaccine is administered subcutaneously (S/C). Signup and view all the answers

Why was there a surge of measles cases in 2019?

The surge was linked to increased refusal to take the MMR vaccine due to reduced confidence associated with autism claims. Signup and view all the answers

What are the recommendations for the rotavirus vaccine concerning administration time?

The first dose of the rotavirus vaccine should be given as soon as possible after 6 weeks of age. Signup and view all the answers

Study Notes

Immunization Goals

Short-term: Prevent disease in individuals.
Long-term: Eradicate disease globally.
Immunization, according to WHO, is the process of making someone immune or resistant to disease through vaccination.
Vaccines stimulate the body's immune system to protect against infection.

Types of Immunity

Active Immunity: Immunity developed by the body's own immune system, usually long-lasting. Acquired through natural disease or vaccination.
Passive Immunity: Protection provided by transferring antibodies from immune individuals.
- Most common: Across the placenta and through mother milk.
- Less common: Blood transfusions and blood products, including immunoglobulin.
- Temporary protection, lasting weeks or months.

Herd Immunity

Also known as community immunity.
Reduces the risk of infection in susceptible individuals by having immune individuals nearby.
Provides "indirect protection" or a "herd effect".
Transmission falls or stops without universal immunity.
More fully immunized children in a community means everyone is safer.

Two Artificial Methods of Immunity

Active immunity: Induced by vaccines, stimulating the adaptive immune system.
Passive immunity: Induced by administering antibodies (immunoglobulins).

Rationale behind Vaccination

Hib (Haemophilus influenzae type b): Can cause meningitis, throat swelling, pneumonia, and death.
Diphtheria: Throat infection with membrane, potential for myocarditis, CNS complications, paralysis, and death (in 7% of cases).
Tetanus: Muscle spasms, breathing problems, convulsions, and death without treatment.
Whooping Cough: Coughing fits, convulsions, coma, brain damage, and death.
Polio: Fever, vomiting, muscle stiffness, nerve damage, muscle paralysis, and death if lung muscles are paralyzed.
Measles: High fever, cough, conjunctivitis, red rash, pneumonia, encephalitis, brain damage, and death.
Mumps: Fever, salivary gland infection, deafness, infertility in males, and encephalitis.
Rubella: Swollen glands, joint pain, rash, and birth defects in unborn children, including blindness, deafness, and mental retardation.

Live Attenuated Vaccines

Modified living organisms weakened to provide immunity.
Advantages: Potent and produce a strong immune response similar to natural infection.
Disadvantages: May cause mild symptoms of disease. Not suitable for immunosuppressed individuals or pregnant women.

Inactivated (Killed) Vaccines

Contain whole dead organisms (killed by chemicals or heat) or parts of the organism.
Advantages: Cannot cause clinical infection and safe for immunosuppressed individuals and pregnant women.
Disadvantages: Less immunogenic than live attenuated vaccines.

Routes of Administration

Oral: OPV (Oral Polio Vaccine) and Rotavirus vaccine.
Intradermal: Delivered into the dermis (top layer of skin). BCG (Bacillus Calmette-Guérin) vaccine.
Subcutaneous: Injections into the subcutaneous layer. MMR (Measles, Mumps, Rubella) and Varicella vaccines.
Intramuscular: Injections into muscle tissue. Many vaccines are given intramuscularly.

BCG Vaccine (Bacillus Calmette-Guérin)

Live attenuated strain of Mycobacterium bovis.
Provides protection against life-threatening complications of tuberculosis such as meningitis and miliary TB, but not 100% protection from tuberculosis itself.
Administered as a single intradermal injection in the deltoid muscle.
Successful vaccination leads to a localized swelling that develops into a papule or ulcer, ultimately healing with a small scar.

Polio Vaccine

Two types:
- OPV (Oral Polio Vaccine): Live attenuated.
- IPV (Inactivated Polio Vaccine): Inactivated.
Both vaccines contain types I, II, and III poliovirus strains and provide lifelong immunity if boosted.
OPV is easier to administer and provides longer immunity.
OPV has been associated with vaccine-associated paralytic poliomyelitis (VAPP) in rare cases.

DTP (Diphtheria, Tetanus, Pertussis) Vaccine

Three doses given intramuscularly at 2, 4, and 6 months of age.

MMR (Measles, Mumps, Rubella) Vaccine

Administered subcutaneously.
Two doses recommended at 12 and 18 months of age.
Concerns regarding autism have decreased confidence in MMR, leading to vaccine hesitancy.

Hepatitis B Vaccine

Administered in four doses: 0, 2, 4, and 6 months of age.
Intramuscular injection in the deltoid muscle for children and adolescents and anterolateral thigh for neonates and infants.
If the mother is HBeAg positive, the baby should receive Hep B IG at birth.

Haemophilus Influenza Type B (Hib) Vaccine

Given in combination with DTaP at 2, 4, and 6 months of age.
Administered intramuscularly.

Pneumococcal Vaccine

PCV 13 (Prevenar) is the most common type, effective against 13 serotypes and protecting against 90% of disease-causing pneumococcal serotypes.
Administered intramuscularly.

Varicella Vaccine

Live attenuated virus vaccine against chicken pox caused by varicella zoster virus.
One dose at 12 months of age.
Administered subcutaneously.

Hepatitis A Vaccine

Two doses of a hepatitis A containing vaccine are needed for long-term protection against hepatitis A virus.
Intramuscularly administered to children and adolescents.

Rota Vaccine

Oral live attenuated vaccine.
WHO recommends administering the first dose as soon as possible after 6 weeks of age.
Considered safe and well-tolerated but carries a low risk of intussusception.

General Contraindications

Serious allergic reaction (anaphylaxis) to a previous vaccine dose.
Moderate or severe current illness with or without fever (more than 38°C).

Vaccination Program in Oman

At birth: BCG and HBV vaccines.
2 months: Hexa-1 (HBV, DTaP, Hib, IPV), PCV13-1, and Rota Vaccine-1.
4 months: Hexa-2 (HBV, DTaP, Hib, IPV), PCV13-2, OPV-1, and Rota Vaccine-2.
6 months: Penta-1 (HBV, DTwP, Hib), OPV-2.
12 months: Vitamin A (100,000 IU), MMR-1, Varicella.
13 months: PCV 13 booster, Penta booster.
18 months: MMR-2, OPV Booster, HAV-1, Vitamin A (200,000 IU).
24 months: HAV-2 and Influenza Seasonal (optional).

School Immunization Schedule in Oman

Grade 1: DT and OPV.
Grade 6: Td.
Grade 11: Td and OPV.

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Description

Explore the critical concepts of immunization, including short-term and long-term goals, types of immunity, and the importance of herd immunity. Understand how vaccines work to protect individuals and communities from infectious diseases.