For which of the following patients would you recommend prophylaxis against mycobacterium avium-intracellulare?

30-year old HIV positive male with CD4 count of 20 cells/microliter and a viral load of < 50 copies/mL

22-year old HIV positive female with CD4 count of 750 cells/microliter and a viral load of 500,000 copies/mL

45-year old HIV positive female with CD4 count of 250 cells/microliter and a viral load of 100,000 copies/mL

50-year old HIV positive female with CD4 count of 150 cells/microliter and a viral load of < 50 copies/mL

36-year old HIV positive male with CD4 count of 75 cells/microliter and an undetectable viral load

An 11-year-old boy is brought to his pediatrician by his parents for the routine Tdap immunization booster dose that is given during adolescence. Upon reviewing the patient’s medical records, the pediatrician notes that he was immunized according to CDC recommendations, with the exception that he received a catch-up Tdap immunization at the age of 8 years. When the pediatrician asks the boy’s parents about this delay, they inform the doctor that they immigrated to this country 3 years ago from Southeast Asia, where the child had not been immunized against diphtheria, tetanus, and pertussis. Therefore, he received a catch-up series at 8 years of age, which included the first dose of the Tdap vaccine. Which of the following options should the pediatrician choose to continue the boy’s immunization schedule?

A single dose of Tdap vaccine at 13 years of age

A single dose of Td vaccine at 18 years of age

A single dose of Td vaccine now

A single dose of Tdap vaccine now

A 7-year-old African-American boy presents to his physician with fatigue, bone and abdominal pain, and mild jaundice. The pain is dull and remitting, and the patient complains it sometimes migrates from one extremity to another. His mother reports that his jaundice and pain have occurred periodically for the past 5 years. At the time of presentation, his vital signs are as follows: the blood pressure is 80/50 mm Hg, the heart rate is 87/min, the respiratory rate is 17/min, and the temperature is 36.5°C (97.7°F). On physical examination, the patient appears to be pale with mildly icteric sclera and mucous membranes. On auscultation, there is a soft systolic ejection murmur, and palpation reveals hepatosplenomegaly. His musculoskeletal examination shows no abnormalities. Laboratory investigations show the following results: Complete blood count Erythrocytes 3.7 x 106/mm3 Hgb 11 g/dL Total leukocyte count Neutrophils Lymphocytes Eosinophils Monocytes Basophils 7,300/mm3 51% 40% 2% 7% 0 Platelet count 151,000/mm3 Chemistry Total bilirubin 3.1 mg/dL (53 µmol/L) Direct bilirubin 0.5 mg/dL (8.55 µmol/L) A peripheral blood smear shows numerous sickle-shaped red blood cells. Among other questions, the patient’s mother asks you how his condition would influence his vaccination schedule. Which of the following statements is true regarding vaccination in this patient?

The patient should receive serogroup B meningococcal vaccination at the age of 10 years.

The patient’s condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.

The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.

The patient should receive the pneumococcal polysaccharide vaccine as soon as possible, because he is at higher risk of getting pneumococcal infection than other children.

The patient should receive serogroup B meningococcal vaccination as soon as possible, because he is at higher risk of getting meningococcal infection than other children.

A 27-year-old man presents to the family medicine clinic for a routine check-up. The patient recently accepted a new job at a childcare center and the employer is requesting his vaccination history. After checking the records from the patient’s childhood, the physician realizes that the patient never had the varicella vaccine. The patient is unsure if he had chickenpox as a child, and there is no record of him having had the disease in the medical record. There is no significant medical history, and the patient takes no current medications. The patient’s heart rate is 82/min, respiratory rate is 14/min, temperature is 37.5°C (99.5°F), and blood pressure is 120/72 mm Hg. The patient appears alert and oriented. Auscultation of the heart reveals no murmurs, rubs, or gallops. The lungs are clear to auscultation bilaterally. With regard to the varicella vaccine, which of the following is recommended for the patient at this time?

Serology then administer the vaccine (2 doses)

Serology then administer the vaccine (1 dose)

A 19-year-old male arrives to student health for an annual check up. He is up to date on his infant and childhood vaccinations up to age 10. At age 12, he received a single dose of the tetanus, diphtheria, and acellular pertussis vaccine, and a quadrivalent meningococcal conjugate vaccine. A month ago, he received the influenza vaccine. The patient has no significant medical history. He takes over the counter ibuprofen for occasional headaches. He has a father with hypertension and hyperlipidemia, and his brother has asthma. He is sexually active with his current girlfriend. He denies tobacco use, illicit drug use, and recent or future travel. The patient’s temperature is 98°F (36.7°C), blood pressure is 118/78 mmHg, pulse is 70/min, and respirations are 14/min with an oxygen saturation of 99% O2 on room air. A physical examination is normal. What of the following is the best recommendation for vaccination?

Tetanus and reduced diphtheria toxoid booster

A 34-year-old man comes to the physician for a routine health maintenance examination. He was diagnosed with HIV 8 years ago. He is currently receiving triple antiretroviral therapy. He is sexually active and uses condoms consistently. He is planning a trip to Thailand with his partner to celebrate his 35th birthday in 6 weeks. His last tetanus and diphtheria booster was given 4 years ago. He received three vaccinations against hepatitis B 5 years ago. He had chickenpox as a child. Other immunization records are unknown. Vital signs are within normal limits. Cardiopulmonary examination shows no abnormalities. Leukocyte count shows 8,700/mm3, and CD4+ T-lymphocyte count is 480 cells/mm3 (Normal ≥ 500); anti-HBs is 150 mIU/mL. Which of the following recommendations is most appropriate at this time?

Tetanus, diphtheria, pertussis vaccine (Tdap)

Measles, mumps, rubella vaccine

A 12-month-old boy presents for a routine checkup. The patient immigrated from the Philippines with his parents a few months ago. No prior immunization records are available. The patient’s mother claims that he had a series of shots at 6 months of age which gave him a severe allergic reaction with swelling of the tongue and the face. She also remembers that he had the same reaction when she introduced solid foods to his diet, including carrots, eggs, and bananas. Which of the following vaccinations are not recommended for this patient?

Intramuscular influenza vaccine

Measles, mumps, and rubella (MMR) vaccine

Immunocompromised host vaccination for USMLE Step 3: High-Yield Pediatrics Lessons

General Principles - The Ground Rules

Live vaccines: Generally contraindicated due to risk of vaccine-induced disease.
Killed/Inactivated vaccines: Safe, but may have ↓ immunogenicity. May require higher doses or extra boosters.
Optimal Timing:
- Administer necessary vaccines preferably ≥4 weeks before initiating immunosuppressive therapy.
- Postpone live vaccines for ≥3 months after chemotherapy; ≥6 months for anti-B cell antibodies (e.g., Rituximab).
Household Contacts: Should be fully vaccinated (including MMR, Varicella) to provide a protective cocoon.

⭐ After solid organ transplantation, live vaccines are generally withheld. Inactivated vaccines can be given starting 3-6 months post-transplant, once immunosuppression is stable.

Vaccination in SOT Children Pre- and Post-Transplant

Primary Immunodeficiencies - Congenital Gaps

Core Principle: Vaccination strategy hinges on the specific immune defect. The main danger lies with live attenuated vaccines causing iatrogenic disseminated disease.
Key Contraindications:
- Severe T-cell defects (e.g., SCID, complete DiGeorge): ALL live vaccines (viral & bacterial) are absolutely contraindicated. Household contacts should also avoid OPV.
- Severe Humoral/B-cell defects (e.g., XLA): Live vaccines contraindicated. Inactivated vaccines are safe but may have poor efficacy; check antibody titres post-vaccination.
- Phagocytic defects (e.g., CGD): Live bacterial vaccines (BCG, oral typhoid) are contraindicated. Live viral vaccines (MMR, Varicella) are generally safe.

⭐ In Severe Combined Immunodeficiency (SCID), rotavirus vaccine can cause severe, persistent gastroenteritis, and BCG can lead to fatal disseminated BCG-osis.

Secondary Immunosuppression - Acquired Weaknesses

General Principle: Avoid live vaccines in severely immunocompromised states. Inactivated vaccines are safe but may have ↓ immunogenicity.
HIV Infection:
- Strategy depends on CD4 count. Live vaccines (MMR, Varicella) are permitted if CD4 count >200 cells/µL & CD4% >15%.
- BCG is absolutely contraindicated regardless of CD4 status.
- Inactivated vaccines are safe but may have a suboptimal response.
Malignancy / Chemotherapy:
- Live vaccines: Contraindicated during and for 3-6 months after chemotherapy. Administer ≥4 weeks before starting.
- Inactivated vaccines: Give ≥2 weeks before or 3 months after chemotherapy for optimal response.
Asplenia (Anatomic or Functional):
- High risk for encapsulated bacteria: S. pneumoniae, H. influenzae type b, N. meningitidis.
- Vaccinate ≥2 weeks before elective splenectomy or ≥2 weeks after.
- Mandatory vaccines: Pneumococcal (PCV, PPSV23), Meningococcal (conjugate, MenB), Hib.

⭐ For patients post-chemotherapy, the standard waiting period for administering live vaccines is at least 3 months. This ensures immune reconstitution and vaccine safety.

Household Contacts - Cocooning the Vulnerable

"Cocooning" protects the immunocompromised by vaccinating their close contacts.

Live vaccines: Generally safe for contacts, with key exceptions.
- Avoid: Oral Polio Vaccine (OPV) due to shedding; use IPV instead.
- Recommended: MMR and Varicella vaccines are encouraged.
Influenza: All household members should receive the annual injectable flu shot.

⭐ If a varicella-vaccinated contact develops a rash, they must avoid the patient until all lesions have crusted over.

High‑Yield Points - ⚡ Biggest Takeaways

Live vaccines are generally contraindicated in immunocompromised hosts.

Exceptions include MMR and VZV, which can be given to asymptomatic HIV-infected children with adequate CD4 counts.

Inactivated vaccines are safe but may elicit a suboptimal immune response.

Household contacts should receive routine vaccines for cocooning, but must avoid the oral polio vaccine (OPV).

Administer live vaccines ≥4 weeks before immunosuppression; inactivated vaccines ≥2 weeks before.

Annual influenza and pneumococcal vaccines are critical in this group.

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