A 28-year-old woman presents to her physician for follow-up. She was found to be HIV-positive 9 months ago. Currently she is on ART with lamivudine, tenofovir, and efavirenz. She has no complaints and only reports a history of mild respiratory infection since the last follow-up. She is also allergic to egg whites. Her vital signs are as follows: the blood pressure is 120/75 mm Hg, the heart rate is 73/min, the respiratory rate is 13/min, and the temperature is 36.7°C (98.0°F). She weighs 68 kg (150 lb), and there is no change in her weight since the last visit. On physical examination, she appears to be pale, her lymph nodes are not enlarged, her heart sounds are normal, and her lungs are clear to auscultation. Her total blood count shows the following findings: Erythrocytes 3.2 x 106/mm3 Hematocrit 36% Hgb 10 g/dL Total leukocyte count 3,900/mm3 Neutrophils 66% Lymphocytes 24% Eosinophils 3% Basophils 1% Monocytes 7% Platelet count 280,000/mm3 Her CD4+ cell count is 430 cells/µL. The patient tells you she would like to get an influenza vaccination as flu season is coming. Which of the following statements is true regarding influenza vaccination in this patient?

The patient can receive approved recombinant or inactivated influenza vaccines, with egg-free formulations preferred due to her egg allergy.

As long as the patient is anemic, she should not be vaccinated.

Influenza vaccination is contraindicated in HIV-positive patients because of the serious complications they can cause in immunocompromised people.

Inactivated or recombinant influenza vaccines fail to induce a sufficient immune response in patients with CD4+ cell counts under 500 cells/µL.

Nasal-spray influenza vaccine is the best option for vaccination in this patient.

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 2-year-old boy is brought in by his parents to his pediatrician. The boy was born by spontaneous vaginal delivery at 39 weeks and 5 days after a normal pregnancy. The boy has received all age-appropriate vaccinations as of his last visit at 18 months of age. Of note, the boy has confirmed sickle cell disease and the only medication he takes is penicillin prophylaxis. The parents state that they plan on enrolling their son in a daycare, which requires documentation of up-to-date vaccinations. The pediatrician states that their son needs an additional vaccination at this visit, which is a polysaccharide vaccine that is not conjugated to protein. Which of the following matches this description?

Live attenuated influenza vaccine

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 28-year-old woman gives birth to a 2.2 kg child while on vacation. The mother's medical records are faxed to the hospital and demonstrate the following on hepatitis panel: hepatitis B surface antigen (HbsAg) positive, anti-hepatitis B core antigen (anti-HbcAg) positive, hepatitis C RNA is detected, hepatitis C antibody is reactive. Which of the following should be administered to the patient's newborn child?

Hepatitis B vaccine, ledipasvir/sofosbuvir

Hepatitis B IVIG, hepatitis B vaccine and ledipasvir/sofosbuvir

Hepatitis B IVIG now, hepatitis B vaccine in one month

A 68-year-old woman with chronic idiopathic thrombocytopenic purpura (ITP) presents to her hematologist for routine follow-up. She has been on chronic corticosteroids for her ITP, in addition to several treatments with intravenous immunoglobulin (IVIG) and rituximab. Her labs today reveal a white blood cell count of 8, hematocrit of 35, and platelet count of 14. Given her refractory ITP with persistent thrombocytopenia, her hematologist recommends that she undergo splenectomy. What is the timeline for vaccination against encapsulated organisms and initiation of penicillin prophylaxis for this patient?

Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for 5 years

Vaccinate: at the time of surgery; Penicillin: at time of surgery for 5 years

Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for an indefinite course

Vaccinate: 2 weeks prior to surgery; Penicillin: 2 weeks prior to surgery for an indefinite course

Vaccinate: at the time of surgery; Penicillin: 2 weeks prior to surgery for an indefinite course

A 3-month-old African American boy presents to his pediatrician’s office for his routine well visit. He was born full-term from an uncomplicated vaginal delivery. He is exclusively breastfeeding and not receiving any medications or supplements. Today, his parents report no issues or concerns with their child. He is lifting his head for brief periods and smiling. He has received only 2 hepatitis B vaccines. Which of the following is the correct advice for this patient’s parents?

He should start vitamin D supplementation.

He should have his serum lead level checked to screen for lead intoxication.

He needs a 3rd hepatitis B vaccine.

Special population considerations for USMLE Step 1: High-Yield Pediatrics Lessons

Preterm & Low Birth Weight - Small Fry, Big Shots

📌 Mnemonic: Preterm Age is Chronological, Except for BCG (PACE-B)

Vaccination for preterm and low birth weight (LBW) infants generally follows the same chronological age as for full-term babies, with key exceptions.

Parameter	Preterm / LBW Infants	Full-Term Infants
Schedule	Follow chronological age (not gestational)	Standard schedule
BCG	Defer until weight is >2 kg	At birth
Hepatitis B	If mother HBsAg-positive & baby <2 kg: Give vaccine + HBIG within 12 hours	At birth

⭐ For preterm infants <2 kg born to HBsAg-positive mothers, both vaccine and immunoglobulin should be given at two separate sites.

Immunocompromised States - Weak Shields, Strong Jabs

General principle: Killed vaccines are safe; live vaccines require caution. Assess the degree of immunosuppression before administering any live vaccine.

Vaccine protection for special populations

Key Conditions & Vaccine Strategy:

Condition	Live Vaccines	Killed Vaccines
HIV	Contraindicated if CD4 count <15%	Safe to administer
High-Dose Steroids	Defer until stable	Safe to administer

-   **Steroid Therapy**: High-dose is **≥2 mg/kg/day** or **≥20 mg/day** for **>14 days**. 
-   **Chemotherapy**: Defer all vaccines until therapy is complete and immune system recovers.
-   **Asplenia / Splenectomy**: Crucial to protect against encapsulated bacteria.
    +   📌 Mnemonic: **P**lease **H**elp **M**e (**P**neumococcal, **H**ib, **M**eningococcal).

⭐ Live vaccines should be deferred for at least 3 months after stopping high-dose steroid therapy.

Chronic Disease - Sick Kids' Shielding

Specific vaccines are crucial for children with chronic conditions to prevent severe complications from otherwise vaccine-preventable diseases.

Chronic Heart & Lung Disease: Require the annual inactivated influenza vaccine.
Chronic Liver Disease: Vaccination against Hepatitis A and Hepatitis B is recommended to prevent further liver damage.
Cochlear Implants: Increased risk for bacterial meningitis, necessitating the pneumococcal vaccine.
Nephrotic Syndrome: Patients are vulnerable to encapsulated bacteria; pneumococcal vaccine is vital, especially during relapses.

⭐ All children with chronic heart or lung disease should receive the annual inactivated influenza vaccine from 6 months of age.

High-Yield Points - ⚡ Biggest Takeaways

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