IMMUNIZATIONS

IMMUNIZATIONS

Required Reading

  • DiPiro Chapter 152: Vaccines

  • DiPiro Chapter 136: Influenza

Objectives

  1. Differentiate between vaccine types

    • Live vs inactivated vaccines

    • Implications for administration and patient safety

  2. Develop individualized immunization plans

    • Considerations include:

      • Timing and spacing of multiple vaccines

      • Pregnancy

      • Immunocompromised status (low vs high level of immunocompromise)

  3. Patient education points and administrative responsibilities

    • Counseling on:

      • Efficacy

      • Adverse effects

      • Reporting requirements

  4. Identify contraindications and precautions for vaccinations

    • True vs perceived allergies

  5. Determine appropriate vaccine agents for:

    • Influenza

    • Pneumococcal

    • Zoster

    • Human Papillomavirus (HPV)

    • Diphtheria, pertussis, tetanus

    • Measles, Mumps Rubella (MMR)

    • COVID-19

  6. Explain pharmacotherapeutic considerations for select vaccines

    • Serious adverse effects

    • Contraindications

    • Necessary adjustments for special populations

  7. Identify medications for prophylaxis and treatment of influenza

    • 1st and 2nd-line medications based on current guidelines

Introduction to Vaccines

  • The purpose of vaccines is to elicit an immune response by introducing antigens.

  • The immune system recognizes these antigens, activating:

    • B cells

    • T cells

  • This leads to:

    • Production of antibodies that attack and destroy the antigens

    • Formation of memory B and T cells for long-lasting immunity.

Types of Vaccines

Live Attenuated Vaccines

  • Characteristics: Made from weakened viruses or bacteria.

  • Mechanism: Must replicate to induce an immune response, mimicking natural infection.

  • Examples: MMR, varicella vaccines.

Inactivated Vaccines

  • Characteristics: Composed of killed viruses or bacteria.

  • Mechanism: Cannot replicate, but the antigen load stimulates an immune response.

  • Immunity level: Often weaker than live attenuated vaccines; may require multiple doses for full immunity.

  • Adjuvants: Sometimes added to enhance immune response.

Types by Specific Vaccines

  • Inactivated Vaccines: DTaP, DT, Td, Tdap; Hep B; Hib; Hep A; RV; HPV; PCV; Influenza; COVID-19.

  • Live Attenuated Vaccines: MMR; Varicella; LAIV; RZV.

Toxoid Vaccines

  • Composition: Made with weakened toxins, often combined with aluminum salts.

  • Function: Prevent diseases caused by toxin-producing bacteria.

  • Example: DTaP.

Polysaccharide vs. Conjugate Vaccines

  • Polysaccharide Vaccines:

    • T-cell independent immunity

    • Short-lived immunity

    • No booster effect

    • Less effective in children < 2 years.

  • Conjugated Polysaccharide Vaccines:

    • T-cell dependent immunity

    • Produces immunologic memory with a booster effect

    • More immunogenic in children < 2 years.

mRNA Vaccines

  • Mechanism: Instruct cells to produce spike protein, triggering an immune response.

  • Characteristics: Does not interact with DNA; quickly broken down post-instruction.

  • Examples: Moderna, Pfizer-BioNtech COVID-19 vaccines.

Adjuvants

  • Definition: Substances added to vaccines to enhance the immune response.

  • Commonly Used Adjuvants:

    • Aluminum (DTaP, PCV, Hepatitis B)

    • MF59 (Flu vaccine)

    • ASO3 (Bird flu vaccine)

    • AS01B (Shingrix)

    • CpG 1018 (HEPLISAV-B).

Vaccine Guidance

  • Annual Recommendations: Published by ACIP, in MMWR (Morbidity and Mortality Weekly Report).

  • Vaccine Schedules:

    • Separate schedules for childhood/adolescents and adults.

    • Catch-up schedules listed.

Multiple Vaccines in One Day

  • Safety: Data shows no adverse effects from receiving multiple vaccines on the same day.

  • Concerns:

    • Risks of infection and outbreaks increase if vaccinations are delayed.

    • Increased healthcare burden and potential anxiety in children.

Minimal Intervals Between Vaccines

  • Guidelines:

    • No minimum interval for two inactivated vaccines.

    • Live vaccines require a 28-day minimum interval if not given simultaneously.

    • Vaccines and antibody combinations:

      • No minimum for inactivated vaccines with antibodies.

      • Live vaccines followed by blood products requires a 2-week interval.

Applying Knowledge to Practice

  • Interval adjustments:

    • Decreasing intervals may interfere with antibody response.

    • Increasing intervals does not reduce effectiveness but delays protection.

Vaccines and Pregnancy

  • Recommendations:

    • Vaccination before pregnancy encouraged.

    • Inactivated influenza vaccine recommended during pregnancy.

    • Tdap for every pregnancy after 20 weeks gestation.

  • Cautions: Risks are theoretical for live vaccines during pregnancy. Pregnant healthcare providers may administer live vaccines.

General Contraindications for Vaccination

  • Definition: Conditions greatly increasing risk of adverse reactions.

  • Universal Contraindication: Severe allergies (immediate and life-threatening anaphylaxis) to vaccine components.

  • Temporary Conditions: Pregnancy and immunosuppression prevent the use of live vaccines.

False Contraindications

  • Conditions Not Preventing Vaccination:

    • Minor illnesses (e.g., mild fever, URI)

    • Illness must be significant enough to warrant referral to hospital for vaccination to be withheld.

Vaccines and Immunosuppression

  • Considerations:

    • Timing of vaccination, type, and duration of immunosuppression affect vaccine efficacy.

    • Live vaccines pose risk of increased adverse effects; inactivated vaccines may have decreased efficacy.

  • Types of Immunosuppression include various conditions such as congenital immunodeficiency, cancer, solid organ transplant recipients, HIV infection, and systemic corticosteroid therapy.

Immunosuppression Recommendations

  • Low-Level Immunosuppression: Includes specific doses of corticosteroids and immunosuppressive medications.

  • High-Level Immunosuppression: More intensive therapies indicated, as well as specific chronic conditions, require more stringent vaccination timing.

General Guidelines for Immunosuppressed Individuals

  • General Rule: Vaccines ideally given before immunosuppression begins.

  • Household Contacts: Can receive inactivated vaccines and most live vaccines around immunocompromised patients.

Specific Vaccine Pearls

Influenza Vaccine

  • Annual Recommendation: Vaccination against Influenza A & B for everyone > 6 months, barring contraindications.

  • Types of Formulations: IIV (inactivated), adjuvanted, recombinant, live attenuated.

  • Vaccine Composition: Trivalent contains two A and one B strain, quadrivalent adds an additional B strain.

  • 2025-2026 Vaccine Composition:

    • Egg-Based Vaccines: specific strains composed for the season.

    • Cell Culture-Based Vaccines: specific strains composed for the season.

Recommendations for Influenza Vaccination

  • Timing: Begin offering vaccines soon after available, ideally by October.

  • Key Points:

    • Annual vaccination is recommended without contraindications.

    • Influenza vaccination minimizes risks associated with illness.

Prophylaxis & Treatment of Influenza

Recommendations for Influenza Prophylaxis

  1. High-risk patients unable to receive vaccines.

  2. Vaccinated patients post influenza activity onset.

  3. Residents of long-term care facilities during outbreaks.

Pharmacologic Treatment of Influenza

  • Neuraminidase Inhibitors: Oseltamivir (Tamiflu), Zanamivir (Relenza).

  • Endonuclease Inhibitor: Baloxavir (Xofluza).

  • Start within 48 hours of exposure for optimal efficacy.

Reye Syndrome

  • Definition: A progressive encephalopathy with hepatic dysfunction following recovery from a viral illness such as influenza.

  • Symptoms: Vomiting, confusion, seizures, coma.

  • Complications: Increased ICP that must be managed.

Treatment of Influenza: Pharmacologic Agents

  • Tamiflu: MOA - Inhibits neuraminidase; indications include ages and doses based on age.

  • Relenza: Inhaled neuraminidase inhibitor; specific age requisites apply.

  • Peramivir: IV treatment; based on age requirements.

  • Baloxavir: Oral endonuclease inhibitor; specific dosing guidelines based on weight.

  • Note: Other classes like Adamantanes are no longer recommended.

Pneumococcal Vaccine

Pediatric Vaccines:

  • 13-Valent Pneumococcal Conjugate Vaccine: attached polysaccharide component, now replaced by newer vaccines.

  • Current recommendations: PCV15 or PCV20.

Available Vaccines:

  • PCV20 and PCV15: Elicit strong response with different numbers of serotypes.

  • PPSV23: Composed of polysaccharide components, effective for high-risk patients, short-lived immunity.

Adult Guidance:

  • Vaccination recommendations: specific guidelines for ages 50+ and those with certain medical conditions, emphasizing separation timelines.

Zoster Vaccine - Shingrix®

  • FDA Approval: 2017, non-live recombinant adjuvanted vaccine.

  • Usage: One-time dose recommended for adults >50.

  • Effective in preventing shingles and recurrent episodes.

HPV Vaccine (9vHPV)

  • Target Strains: Cancer-linked 16 & 18, genital warts-linked 6 & 11.

  • Recommendations: Aiming for vaccination at ages 11-12; guidelines through 45 years.

  • Safety Considerations: Specific contraindications outlined.

Tetanus, Diphtheria, and Pertussis Vaccines (Tdap)

  • Recommendations: Aged recommendations listed for DTaP and Tdap series in early life and for adults.

  • Differences: Between DTaP and Tdap focused on dosing to minimize local reactions.

MMR Vaccine

  • Series: Live-attenuated, two doses for children at specified ages.

  • Contraindications: Allergy to components, pregnancy, and certain medical conditions.

COVID-19 Vaccines

  • Overview: Most extensive public health immunization effort; details on FDA approvals and emergency authorizations.

  • Current Vaccines: Pfizer, Moderna FDA approved; others either EUA or not available.

Adverse Reactions and Reporting

  • Common Reactions: Vary by vaccine type, general guidelines on response to reactions given.

  • True vs. False Allergies: Distinction between immediate allergic reactions and other adverse effects.

Vaccine Adverse Event Reporting System (VAERS)

  1. To report or inquire about adverse reactions following vaccination, utilize resources provided by VAERS.

National Vaccine Advisory Committee Standards for Adult Immunization

  • Recommendations: Regular updates, documentation practices, and patient follow-up for future vaccinations.

Communicating about Vaccinations

Patient Communication Strategies

  • Individualized approaches and the use of motivational techniques to improve vaccination rates and address concerns.

Common Myths about Vaccinations

  • Clarifies misconceptions about vaccines and their effects.