Immunization: Types of Immunity

• Immunization is the process of inducing active or passive immunity artificially through immunobiologic administration.
• Immunity: An inherited or acquired resistance to a specific disease's effects.
• Natural immunity refers to innate resistance to infection or toxicity.
• Acquired immunity occurs after exposure to an invading agent like bacteria, viruses, or toxins.
• Active immunity is when immune bodies are formed against specific antigens, either naturally through clinical or subclinical disease or via artificial introduction of antigens.
• Passive immunity: Temporary immunity via transfusing immunoglobulins/antitoxins from another human/animal or naturally from mother to fetus.
• Antibody: A serum protein formed in response to a specific antigen.
• Antigen: Foreign substances (bacteria, viruses, toxins) that stimulate antibody formation.
• Vaccine: A suspension of live (attenuated) or inactivated microorganisms administered to induce immunity and prevent infectious disease.
• Toxoid: A modified bacterial toxin that is nontoxic but still stimulates antitoxin formation.

Hepatitis B Virus (HBV)

• HBV infections in childhood/adolescence can lead to fatal cirrhosis or liver cancer in adulthood; up to 90% of infants infected perinatally and 25-50% infected before age 5 become chronically infected.
• Hepatitis B immune globulin (HBIG) dose: 0.5 ml within 12 hours of birth.
• Preterm infants get a dose at birth, followed by three additional doses at 1, 2, and 6 months.
• Immunization is encouraged for all children by age 11.
• Administer the vaccine intramuscularly in the vastus lateralis for newborns or in the deltoid for older infants/children.
• Avoid the dorsogluteal site

Hepatitis A Virus (HAV)

• Spread through the fecal-oral route, person-to-person contact, contaminated food/water, or blood transfusion (rarely).
• Symptoms: Fever, malaise, anorexia, nausea, abdominal discomfort, dark urine, and jaundice.
• HepA vaccine is recommended for all children starting at 1 year (12-23 months).
• The second dose in a two-dose series should be given no sooner than 6 months after the first.

Diphtheria

• Administered in combination with tetanus and pertussis vaccines (DTaP) or DTaP and Hib vaccines for children younger than 7 years of age.
• Can be combined with a conjugate H. influenzae type B vaccine.
• Also available in a combined vaccine with tetanus (DT) for children under 7 with contraindications to pertussis vaccine.
• Can be given with tetanus and acellular pertussis (Tdap) for children 11+ or as a single antigen.
• Protective antitoxin persists for 10+ years with boosters every 10 years for life.
• Respiratory manifestations include nasopharyngitis or obstructive laryngotracheitis.
• Cutaneous manifestations involve vaginal, otic, conjunctival, or cutaneous lesions.

Tetanus

• Available forms: Tetanus toxoid, tetanus immunoglobulin (TIG), and tetanus antitoxin (equine antitoxin).
• Tetanus toxoid provides protective antitoxin levels for about 10 years.
• Children should receive Td boosters every 10 years.
• Boostrix (Tdap) is for people 10+ (including those ≥65 years of age), and Adacel (Tdap) is for individuals 10-64 years.
• Passive immunity is available for wound management via TIG.

Pertussis

• Pertussis vaccine is recommended for all children aged 6 weeks-6 years without neurological contraindications.
• Available forms: Whole-cell pertussis vaccine (inactivated cells of Bordetella pertussis) and acellular pertussis vaccine (one or more immunogens from B. pertussis).
• Acellular pertussis vaccine is recommended for the first three immunizations (2, 4, and 6 months) with diphtheria and tetanus (DTaP).
• Several forms of acellular pertussis vaccine are currently licensed for use in infants: Daptacel, Pediatrix, Kinrix (DTaP and IPV), and Infanrix (diphtheria, tetanus toxoid, and acellular pertussis conjugate).

Polio

• Children should receive four doses of IPV (inactivated poliovirus vaccine) at 2 months, 4 months, 6-18 months, and 4-6 years.
• Exclusive use of IPV is due to the rare risk of vaccine-associated polio paralysis (VAPP) from OPV.
• Pediarix contains DTaP, hepatitis B, and IPV and can be used as the primary immunization starting at 2 months.
• Kinrix contains DTaP and IPV and may be used as the fifth DTaP dose and fourth IPV dose in children ages 4-6 years whose previous doses have been with Infanrix and/or Pediarix for the first three doses and Infanrix for the fourth dose.

Measles

• Measles (rubeola) vaccine is given at 12-15 months.
• During measles outbreaks, the vaccine can be given at 6-11 months, followed by a second dose after 12 months.
• A second measles immunization is recommended at 4-6 years.
• Children vaccinated before 12 months should get two additional doses starting at 12-15 months, separated by at least 4 weeks.
• MMRV vaccine is an attenuated live virus vaccine for children 12-15 months or 4-6 years old.
• Children with HIV should not receive the MMRV vaccine.
• Vitamin A supplementation is effective in reducing morbidity and mortality risks associated with measles in developing countries.

Mumps

• Mumps virus vaccine is recommended at 12-15 months, typically with measles and rubella.
• Should not be given to infants younger than 12 months due to maternal antibodies interfering with immune response.
• Mumps immunization is recommended for all individuals born after 1957 who may be susceptible.

Rubella

• Rubella is mild in children, but poses risks to the fetus if a pregnant woman is infected.
• Rubella immunization is aimed at protecting the unborn child.
• Recommended for all children at 12-15 months and at school entry (4-6 years) or sooner per MMRV vaccine recommendations.
• Counsel patients to avoid pregnancy for 28 days after rubella-containing vaccine.
• Rubella vaccine is not given to pregnant women due to the risk to the developing fetus.

Haemophilus influenzae Type b (Hib)

• Hib conjugate vaccines protect against bacterial meningitis, epiglottitis, bacterial pneumonia, septic arthritis, and sepsis.
• MenHibrix is licensed for children 6 weeks-18 months, protecting against meningococcal (groups A, C, Y, and W-135) and Hib; given in a four-dose series at 2, 4, 6, and 12-15 months.
• All Hib vaccines are administered intramuscularly, separately from concurrent vaccinations.

Varicella

• Cell-free live-attenuated varicella vaccine is recommended for susceptible children.
• Administer 0.5 ml subcutaneously.
• The first dose is recommended at 12-15 months, with a second dose at 4-6 years.
• The second varicella vaccine may be given before 4 years if there is a 3 month period between doses.
• Children 13+ who are susceptible get two doses at least 4 weeks apart.
• Keep the vaccine frozen in lyophilic form and use within 30 minutes of reconstitution.
• Varicella vaccine may be given with MMR.

Pneumococcal Disease

• Streptococcal pneumococci cause bacterial infections in children under 2 years.
• 13-valent pneumococcal vaccine (PCV13 [Prevnar13]) is standard for children 6 weeks-24 months.
• PCV13 vaccine is administered at 2, 4, and 6 months, with a fourth dose at 12-15 months.
• A single supplemental dose of PCV13 is recommended for children 14-59 months who have received an age-appropriate series.

Influenza

• Influenza vaccine is recommended annually for children 6 months to 18 years.
• Inactivated influenza vaccine (IIV) may be given to healthy children 6 months and older.
• Administer the vaccine in early fall before flu season and repeat yearly.
• The intramuscular vaccine is given as two doses 4 weeks apart in first-time recipients younger than 9 years old.
• The dose is 0.25 ml for children 6-35 months and 0.5 ml for children 3 years and older.
• Assess egg allergenic reaction (mild vs. severe) before administering the vaccine to children with egg allergy.

Meningococcal Disease

• Infants younger than 1 year are particularly susceptible.
• Adolescents and young adults have the highest fatalities.
• Neisseria meningitidis is the leading cause of bacterial meningitis in the U.S.
• Children at increased risk get a two-dose series of MenACY-D (Menactra) or MenACY-CRM (Menveo), both MCV4 vaccines.
• Menactra is licensed for children as young as 9 months, while Menveo is licensed for children 2 years and older.
• MCV4 (Menveo or Menactra) is administered intramuscularly (0.5 ml).
• Immunization with MCV4 is contraindicated in persons with hypersensitivity to any vaccine components, including diphtheria toxoid, and to rubber latex.

Rotavirus

• Rotavirus is a leading cause of severe diarrhea in infants and young children, transmitted via the fecal-oral route.
• Two rotavirus vaccines available: RotaTeq (RV5) and Rotarix (RV1).
• Infants are routinely immunized with three doses of RotaTeq at 2, 4, and 6 months or two doses of Rotarix at 2 and 4 months.
• Both vaccines are administered orally.
• Infants who contract rotavirus before completing the series finish vaccinations following the standard intervals (but not after 32 weeks of age).

Human Papillomavirus (HPV)

• Human papillomaviruses (HPVs) consist of cutaneous and genital types, genital HPVs can cause cancers.
• Gardasil 9 is the only HPV vaccine available in the United States
• Administered intramuscularly, preferably in the deltoid muscle, in three doses; the first dose is given at 11-12 years, the second 1-2 months after, and the third 6 months after the first.
• The vaccine is recommended for both boys and girls at a minimum age of 9 years and a maximum age of 26 years
• Women who get the HPV vaccines must continue regular Pap tests.

Reactions

• Vaccines for routine immunizations are among the safest and most reliable drugs available.
• Inactive components enhance effectiveness and safety: preservatives, stabilizers, adjuvants, antibiotics, and purified culture medium proteins.
• Hepatitis B vaccine is prepared from yeast cultures; yeast hypersensitivity precludes vaccination without consulting an allergist.
• Trace neomycin is used in certain vaccine preparations; persons with anaphylactic reactions to neomycin should avoid those vaccines.
• Influenza vaccines contain egg protein, but inactivated influenza vaccine poses no anaphylactic risk to children with egg allergy.
• Most vaccine preparations now contain vial stoppers with a synthetic rubber to prevent latex allergy reactions
• Side effects from inactivated antigens (e.g., DTaP) typically occur within hours/days and include local tenderness, erythema, and swelling at the injection site; low-grade fever; and behavioral changes.
• If epinephrine is administered for severe reactions, observe for adverse reactions such as tachycardia, hypertension, irritability, headaches, nausea, and tremors.

Contraindications and Precautions

• Unfounded fears can prevent a child from protection from life-threatening diseases.
• Parents are concerned about adverse reactions, such as autism, pain, compromised immunity, and death associated with vaccinations
• A contraindication increases the risk for a serious adverse reaction e.g., not giving a live virus vaccine to an immuno-compromised child.
• A precaution might increase the risk for a serious adverse reaction.
• The general contraindication for all immunizations is a severe febrile illness.
• Minor illnesses, such as the common cold, are not contraindications.
• Live virus vaccines should not be given to severely immunocompromised persons or persons with unknown immune function.
• Another contraindication to live virus vaccines (MMR, varicella, and rotavirus) is recent passive immunity through blood transfusions, immunoglobulin, or maternal antibodies.
• Administration of MMR and varicella should be postponed for a minimum of 3 months after passive immunization with immunoglobulins and blood transfusions
• An anaphylactic reaction to a vaccine or its component is a true contraindication.
• Pregnancy is a contraindication to MMR vaccines, although the risk of fetal damage is primarily theoretic.
• Breastfeeding is not a contraindication for any vaccine.
• A family history of seizures or adverse event following vaccination, penicillin allergy, allergies to duck meat or duck feathers, and a family history of sudden infant death syndrome (SIDS) are not contraindications to receiving childhood vaccines

Communicating with Parents

• Provide accurate, user-friendly info on vaccine information statements (VIS).
• Understand the parent is concerned about their child's health.
• Tailor the discussion and avoid judgmental or threatening language.
• Be flexible and provide options regarding administering multiple vaccines.
• Involve the parent in minimizing potential adverse effects (e.g., administering acetaminophen before the vaccine).

Administration

• Precautions include proper vaccine storage and injection procedures.
• Store refrigerated vaccines on a center shelf, not in the door.
• Wrap the vial in aluminum foil for protection against light.
• Ensure no vaccine is used after its expiration date
• DTP (or DTaP) vaccines contain an adjuvant, so intramuscular injection technique is crucial.
• The order of injections is arbitrary when administering multiple injections.
• Document: administration date, manufacturer, vaccine lot number, name/address/title of the administrator, administration site/route, and informed consent.
• Report adverse reactions after administration to the Vaccine Adverse Event Reporting System

Childhood immunization status

• Measure - Children 2 years of age who had four diphtheria, tetanus and acellular pertussis (DTaP); three polio (IPV); one measles, mumps, and rubella (MMR); three H. influenzae type B (HiB); three hepatitis B (HepB); one chickenpox (VZV); four pneumococcal conjugate (PCV); two hepatitis A (HepA); two or three rotavirus (RV); and two influenza (flu) vaccines by their second birthday.
• Numerator - Number of children who have evidence showing they received recommended vaccines during the measurement time.
• Denominator - Number of children who turn 2 years of age during the measurement year are eligible for inclusion