PA 413 Primary Care I & Infectious Disease – Vaccine & HIV Vocabulary Flashcards

Vaccination Fundamentals

• Vaccines provide direct protection to the individual and can reduce transmission in the population (direct vs indirect effects).
• Total of 17 diseases now preventable through routine vaccination (as noted in the transcript).
• Five major categories of vaccination programs:
  • Routine childhood
  • Routine adult
  • Postexposure prophylaxis
  • Travel
  • Work-related/special circumstances
• Question to consider: Which immunization strategy is most effective? Immunizations in general provide both direct protection and potential indirect protection to the community.

Direct vs. Indirect Effects of Vaccination

• Direct effect: protection against infection and a decrease in severity of clinical illness in the vaccinated individual.
• Indirect effect: reduction of transmission from immunized persons to others, contributing to community protection (herd effect) if coverage is high enough.

Immunity Types: Active vs Passive

• Active immunity:
  • Involves administration of a vaccine or toxoid.
  • Provides long-term immunity after an incubation period (typical onset of protective immunity takes about 2–4 weeks post-vaccination).
• Passive immunity:
  • Involves administration of preformed antibodies.
  • Provides immediate protection but is temporary.
• Summary: Immunity is not typically established immediately after vaccination; timing matters for protection during outbreaks or exposure.

Immunity Types: Active vs Passive (Continued)

• Important nuance: Some vaccines confer both immediate (partial) protection via maternal antibodies in infants or via immune priming, but true long-term protection requires time for an active immune response to develop.

Types of Immunization: Live Attenuated vs Inactivated

• Live attenuated vaccines:
  • Derived from wild-type pathogens, weakened so they rarely cause disease in healthy hosts.
  • Small dose stimulates robust immune response similar to natural infection, often with lasting immunity.
  • May cause minor side effects; typically produce strong, durable immunity.
• Inactivated vaccines:
  • Not live; cannot cause disease.
  • Immunity tends to be shorter-lasting, may require boosters.
• Practical note: Many vaccines can be given concurrently; consider syringe/needle changes and administration routes to avoid interference.

Administration: Practical Notes

• Majority of vaccines can be administered simultaneously with other vaccines.
• For safety: use a new syringe and needle for every vaccine (to prevent contamination).
• When administering more than one vaccine:
  • Location options:
  • Intramuscular (IM) in the deltoid (adult) or other muscle as appropriate
  • Subcutaneous (SC) in the triceps region
• Considerations when giving live vaccines with immunoglobulin preparations: generally avoid co-administration; space them appropriately when necessary.

Administration: Injection Site and Scheduling

• Common IM site: Deltoid muscle for adults.
• Common SC site: Triceps area.
• Vaccines are typically given in a specific schedule; verify dosage and interval for each product.

Vaccine Side Effects and Contraindications

• Common local and systemic reactions:
  • Induration, erythema, tenderness at injection site
  • Low-grade fever, myalgia
• Most vaccines can be given with mild, non-severe symptoms (e.g., mild respiratory or flu-like symptoms) unless contraindicated.
• Contraindications include:
  • For antibiotics use: only specific vaccines (e.g., oral typhoid and cholera) may have antibiotic-related considerations
  • Allergy to vaccine components (e.g., neomycin, streptomycin, polymyxin B)
  • History of anaphylaxis to a vaccine component
• Special populations (pregnant, immunocompromised) have additional considerations described in subsequent sections.

Specific Populations: Special Considerations

• Pregnant and/or breastfeeding individuals:
  • Should not receive live attenuated vaccines.
  • If not pregnant but planning pregnancy, wait at least 4 weeks after a live vaccine before attempting conception.
• Immunocompromised individuals:
  • Severely immunocompromised should not receive live attenuated vaccines.
  • Inactivated vaccines can be given but may elicit a weaker immune response.
• Immunocompetent individuals living with someone who is immunocompromised:
  • Can receive live attenuated vaccines but should avoid varicella, varicella zoster, and live attenuated influenza vaccines in such close-contact scenarios to minimize risk of transmission.

Hepatitis A (Hep A)

• Vaccine type: Inactivated, recombinant-like clinical vaccine; refrigerated storage; administered intramuscularly (IM).
• Examples in slides: Havrix®, Vaqta® (both INACTIVATED vaccines).
• Dosing schedule for adults:
  • 0 months: 1st dose
  • 6–12/18 months after 1st dose: 2nd dose
• Indications:
  • Travel to high-incidence regions not vaccinated in childhood
  • General at-risk populations as per clinician guidance
• Contraindications: Anaphylaxis to a vaccine component
• Most common reactions: fever, injection-site erythema, swelling, rash

Hepatitis B (Hep B)

• Vaccine type: Recombinant, inactivated vaccine (e.g., Energix-B®, Heplisav-B®, Recombivac HB®).
• Dosing schedule (typical adult course):
  • 0 months: 1st dose
  • 1 month after 1st dose: 2nd dose
  • 6 months after 1st dose: 3rd dose (note: Heplisav-B has a different schedule: 0 months-1st dose; 1 month after 1st dose-2nd dose; 6 months after 1st dose-3rd dose)
• Indications: Adults at risk for infection or exposure risks; healthcare workers; household contact with HBV-infected persons; individuals with end-stage renal disease or diabetes, chronic liver disease, HIV, traveling to high-risk areas, incarceration.
• Contraindications: Anaphylaxis to vaccine component (yeast)
• Common side effects: Injection-site pain, erythema, swelling; fever; headache

Hepatitis B: Indications for Adults

• At-risk groups for infection via sexual exposure
• Household contact with active HBV infection
• Exposure to blood products
• End-stage renal disease, diabetes mellitus, Hepatitis C, chronic liver disease, HIV
• Travel to regions with higher HBV prevalence
• Incarcerated populations
• Vaccination should be prioritized for those with these risk factors

Hepatitis B Vaccination: Titers and Non-Responders

• Some individuals do not mount protective immunity after vaccination (non-responders).
• If negative serology, consider revaccination or post-vaccination titers to assess immunity.
• Laboratory titer testing commonly requested: Hepatitis B surface antibody (HBsAb).

Human Papillomavirus (HPV) – Gardasil 9

• Vaccine: 9-valent recombinant HPV vaccine (GARDASIL®9) for 9 HPV types: 6, 11, 16, 18, 31, 33, 45, 52, 58
• Formulation: 0.5 mL single-dose syringe; contains varying microgram amounts per type across 9-valent formulation
• Dosing schedule (adult vaccination):
  • Typically recommended for ages 19–26; some guidelines extend up to 45 depending on risk and guidelines
  • Three-dose series:
  • 0 months: 1st dose
  • 1–2 months after 1st dose: 2nd dose
  • 6 months after 1st dose: 3rd dose
• Contraindications: Anaphylaxis to vaccine component (yeast); pregnancy is a precautionary exclusion in some guidelines
• Most common reactions: Injection-site pain, erythema, swelling; low-grade fever

Human Immunodeficiency Virus (HIV) — Epidemiology and Pathophysiology

• Global prevalence and US data:
  • HIV prevalence in US: approximately 1.2 imes 10^6 people
  • Global prevalence: approximately 37 imes 10^6 people
  • In 2022 US newly diagnosed: about 37{,}981 cases
  • Of new diagnoses: 79 ext{%} male; 67 ext{%} male-to-male sexual contact as primary transmission route; 41 ext{%} Black/African American; 37 ext{%} aged 25–34; 49 ext{%} in the Southern US
• Pathophysiology:
  • HIV is an RNA retrovirus transmitted via sexual contact, parenteral exposure, and maternal transmission
  • Virus attaches to CD4 receptors on T lymphocytes and enters the cell
  • Reverse transcriptase converts RNA to DNA; viral DNA is integrated into host genome; virions produced and disseminated
  • HIV mutates to evade immune response and downregulates MHC class I on infected cells; CD4+ T cells are progressively depleted
• Clinical stages/signs:
  • Primary infection: 1–4 weeks after exposure; flu-like, lasts 3–14 days
  • Asymptomatic infection
  • Symptomatic infection
  • AIDS: significant immune suppression (CD4 count < 200 ext{ cells/mm}^3) with opportunistic infections and/or certain cancers

HIV Clinical Course: Signs and Symptoms by Stage

• Asymptomatic infection: can last up to ~10 years
• Symptomatic infection: persistent generalized lymphadenopathy; mucocutaneous fungal infections; oral hairy leukoplakia; widespread molluscum contagiosum and warts; psoriasis/dermatitis flares; disseminated herpes zoster
• AIDS-defining illnesses: opportunistic infections and certain malignancies (e.g., Kaposi sarcoma, cervical dysplasia)
• Opportunistic infections commonly seen in AIDS include: Pneumocystis jirovecii pneumonia, cryptococcosis, histoplasmosis, Mycobacterium avium complex (MAC), toxoplasmosis, CMV, candidiasis, cryptococcus, and others

HIV Diagnosis: Serology and NAATs

• Antibody/antigen testing timelines:
  • HIV antigen detectable early (as early as ~13–20 days post-infection) for certain p24 antigens
  • HIV antibody detection: IgM around ~20 days; IgG around ~30 days post-infection
• Fifth-generation HIV antibody/antigen tests combine antigen and antibody detection
• Nucleic acid amplification tests (NAATs) detect HIV RNA as early as ~6–8 days after infection
• Testing strategy:
  • Use combination antigen/antibody assays first, followed by confirmatory testing
  • NAATs used when exposure is too recent for antibody/antigen to be detectable

HIV Monitoring and Biomarkers

• Key monitoring parameters at diagnosis and regularly (every 3–6 months):
  • CD4+ T lymphocyte count (single best indicator of disease progression risk; low counts correspond to higher AIDS risk; <200 cells/mm^3 is AIDS)
  • CD4+ percentage and quantitative viral load (HIV RNA, “viral load”)
• Goals:
  • Reduce HIV RNA to undetectable levels; target: <50 copies/mL by 6 months of therapy
  • If detectable RNA persists, reassess adherence, drug interactions, and resistance
• Drug resistance testing: genotypic resistance assessment to guide initial treatment and regimen changes

HIV Monitoring: Laboratory and Preventive Care

• CBC and CMP to monitor hematologic, renal, and liver function, electrolyte balance
• STI screening (syphilis with RPR and confirmatory treponemal test)
• Hepatitis B and C screening (HBsAg, HBsAb, HCV antibody)
• Toxoplasmosis screening (Toxoplasma gondii IgG)
• TB screening (PPD or IGRA)
• CMV serology (CMV IgG) and HPV/pap screening when applicable
• Gynecologic/other screening: pelvic inflammatory disease screening; annual Pap testing

HIV Health Maintenance: Vaccinations and Preventive Care

• Vaccinations for people living with HIV (PLWH):
  • Pneumococcal vaccines (PCV15/PCV20 followed by PPSV23 per guidelines)
  • Influenza vaccine annually
  • Hepatitis A and B vaccines if immunity is lacking
  • Human papillomavirus (HPV) vaccine if applicable
  • Meningococcal vaccine when indicated
  • Measles, mumps, rubella (MMR) and Varicella vaccines if CD4+ count > 200 cells/mm^3 and no contraindications
• Measles, Mumps, and Rubella (MMR) and Varicella vaccines are typically given to those with adequate CD4 counts due to opportunistic infection risk

HIV Therapy: Antiretroviral Treatment (ART) Principles

• Treatment goal: reduce and maintain plasma HIV RNA at the lowest possible level
• Regimen options commonly used:
  • 2 NRTIs + 1 INSTI
  • 2 NRTIs + 1 PI with booster
  • 2 NRTIs + 1 NNRTI
  • 1 NRTI + 1 INSTI (exceptional cases)
• NRTIs: block reverse transcriptase; common agents include Abacavir, Didanosine, Emtricitabine, Lamivudine, Stavudine, Tenofovir, Zidovudine; side effects include decreased bone density, bone marrow suppression, insulin resistance, dyslipidemia, lipodystrophy
• INSTIs: block integrase; agents include Bictegravir, Cabotegravir, Dolutegravir, Elvitegravir, Raltegravir; side effects include rash, myopathy
• NNRTIs: bind reverse transcriptase; risk of Stevens-Johnson syndrome, toxic epidermal necrolysis, hepatotoxicity; agents include Delaviridine, Doravirine, Efavirenz, Etravirine, Nevirapine, Rilpivirine
• PIs: inhibit protease; side effects include GI upset, nephrolithiasis, hyperglycemia, dyslipidemia, lipodystrophy; agents include Atazanavir, Darunavir, Fosamprenavir, Lopinavir, Indinavir, Nelfinavir, Ritonavir, Saquinavir; Ritonavir used as booster; Cobicistat is a booster (not antiretroviral)
• Treatment failure:
  • Defined by inadequate viral suppression, rebound in RNA, or clinical progression
  • Causes: viral resistance, drug interactions, poor adherence, absorption issues

HIV Opportunistic Infections and Malignancies

• Pneumocystis jirovecii pneumonia (PJP):
  • Occurs at CD4 < 200 cells/mm^3
  • Symptoms: fever, malaise, nonproductive or productive cough, dyspnea
  • Workup: CXR with possible diffuse interstitial involvement; CT with ground-glass opacity; LDH elevation; sputum culture; bronchoalveolar lavage
  • Treatment: O2 therapy; mild-moderate disease: TMP-SMX; alternatives as indicated; adjunct corticosteroids for moderate-severe disease
  • Prophylaxis: TMP-SMX (DS) daily; alternatives include dapsone, atovaquone, or pentamidine depending on tolerance and access
• Histoplasmosis (Histoplasma capsulatum):
  • Associated with Mississippi/Ohio river valleys; CD4 < 150 cells/mm^3
  • Therapy: Amphotericin B then itraconazole; prophylaxis with itraconazole in certain cases
• Cryptosporidiosis: persistent diarrhea in immunocompromised; management supportive; nitazoxanide may help but not curative; CD4 restoration critical
• Mycobacterium avium complex (MAC):
  • Disseminated disease in those with CD4 < 50 cells/mm^3; treatment typically macrolide (azithromycin or clarithromycin) + ethambutol + a fluoroquinolone or aminoglycoside; prophylaxis for MAC if CD4 < 50 cells/mm^3
• Toxoplasmosis: CD4 < 100–200 cells/mm^3
  • Signs: fever, headache, focal neuro deficits
  • Workup: Toxoplasma IgG/IgM; brain imaging showing ring-enhancing lesions
  • Treatment: Sulfadiazine + pyrimethamine + leucovorin for 6 weeks; counseling on prevention (avoid undercooked meat, avoid litter boxes, gloves when gardening)
  • Prophylaxis: TMP-SMX daily or DS three times weekly if seropositive and CD4 < 100
• Candidiasis (Oral and Esophageal):
  • Oropharyngeal: Fluconazole with topical antifungals; esophageal therapy includes higher-dose fluconazole or alternative antifungals
• CMV (Cytomegalovirus):
  • Risk with CD4 < 100; retinitis is a major concern
  • Treatment options include valganciclovir or IV ganciclovir; ophthalmologic monitoring
• Kaposi sarcoma (HHV-8):
  • Can occur at any HIV stage; lesions can be cutaneous or visceral
  • Primary management focuses on controlling HIV with ART; localized radiation or chemotherapy for extensive disease

Immunization and HIV: Practical Notes

• Immunization considerations for PLWH:
  • Vaccinate according to standard schedules when CD4 count > 200 cells/mm^3 and no contraindications
  • Pneumococcal vaccines (PCV15/PCV20 followed by PPSV23 as applicable)
  • Influenza vaccine annually; Hepatitis A and B vaccines if non-immune
  • HPV vaccine if indicated; MMR and Varicella as appropriate based on immunity and CD4 thresholds
  • Measles, mumps, rubella and varicella vaccines are considered with careful assessment of immune status

Therapeutic Goals and Considerations (ART) – Quick Reference

• Treatment goal: maintain HIV RNA as low as possible; ideally undetectable
• Major regimens (examples):
  • Two NRTIs + one INSTI
  • Two NRTIs + one PI boosted with ritonavir or cobicistat
  • Two NRTIs + one NNRTI
  • One NRTI + one INSTI (in select cases)
• Monitoring: regular LDH, CBC, CMP, HIV RNA, CD4 counts; watch for adverse effects and drug interactions
• Drug class side effects to monitor:
  • NRTIs: bone density loss, bone marrow suppression, metabolic changes
  • INSTIs: rarely rash/myopathy
  • NNRTIs: rash, hepatotoxicity, vivid dreams; risk of severe reactions with some agents
  • PIs/boosters: metabolic complications, lipid abnormalities, insulin resistance; nephrolithiasis less common
• Treatment failure definitions and management require reassessment of adherence, resistance, and drug interactions; switch strategies guided by resistance testing

Non-responders and Serology: Interpreting Vaccination Titers

• Non-responders: individuals who do not mount protective antibody titers post-vaccination
• Use post-vaccination titers to determine seroprotection where available
• Common titers checked in practice include:
  • Hepatitis B surface antibody (HBsAb)
  • Measles, Mumps, Rubella (MMR) IgG
  • Varicella IgG
• Interpretation of results is guided by clinical context and laboratory reference ranges; a documented lack of immunity may prompt revaccination or additional boosters

Immunology: Laboratory Titers and Interpretation (Example Results)

• Example interpretation notes (taken from sample lab report snapshots):
  • Measles IgG: positive indicates prior infection or vaccination
  • Rubella IgG: negative/positive indicated based on reference ranges; equivocal results may require retesting
  • Varicella IgG: positive indicates immunity; negative indicates non-immunity or past exposure variability
• Important: Lab results must be interpreted in the context of exposure risk and clinical history; if uncertainty remains, retest or consult infectious disease guidelines

Summary of Key Measurable Targets and Guidelines

• HIV RNA goal with ART: < 50 copies/mL by 6 months of therapy
• AIDS definition: CD4+ count < 200 cells/mm^3
• Vaccination guidelines emphasize concurrent administration when appropriate, with attention to live vs non-live vaccines in immunocompromised populations
• Prophylaxis for opportunistic infections is guided by CD4 thresholds and infection risk (e.g., PJP prophylaxis at CD4 < 200)

References (as cited in the slides)

• Goroll, A. H., & Mulley, A. G. (2021). Primary care medicine: Office evaluation and management of the adult patient. Wolters Kluwer.
• Fauci A.S., et al. (2022). Harrison's Principles of Internal Medicine, 21e. McGraw-Hill Education.
• CDC HIV data and guidelines: https://www.cdc.gov/hiv/data-research/facts-stats/index.html
• HIV clinical guidelines: https://clinicalinfo.hiv.gov/en/guidelines/hiv-clinical-guidelines-adult-and-adolescent-arv/what-start-initial-combination
• Vaccination pink book: https://www.cdc.gov/vaccines/pubs/pinkbook/index.html
• General titers and interpretation resources (laboratory references) as per clinical context

End of Notes