A 12-month-old girl is brought to her pediatrician for a checkup and vaccines. The patient’s mother wants to send her to daycare but is worried about exposure to unvaccinated children and other potential sources of infection. The toddler was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines. She does not walk yet but stands in place and can say a few words. The toddler drinks formula and eats a mixture of soft vegetables and pureed meals. She has no current medications. On physical exam, the vital signs include: temperature 37.0°C (98.6°F), blood pressure 95/50 mm Hg, pulse 130/min, and respiratory rate 28/min. The patient is alert and responsive. The remainder of the exam is unremarkable. Which of the following is most appropriate for this patient at this visit?
Q22
A 3-year-old boy is brought to the emergency room by his mother with fever and difficulty breathing after receiving the BCG vaccine. He has never had a reaction to a vaccine before. He has a history of 2 salmonella infections over the past 2 years. He was born at 35 weeks’ gestation and spent one day in the neonatal intensive care unit. His parents' family histories are unremarkable. His temperature is 101°F (38.3°C), blood pressure is 80/55 mmHg, pulse is 135/min, and respirations are 24/min. On examination, he appears acutely ill. He has increased work of breathing with intercostal retractions. A petechial rash is noted on his trunk and extremities. A serological analysis in this patient would most likely reveal decreased levels of which of the following cytokines?
Q23
A 1-year-old immigrant girl presents to her pediatrician for a routine well-child check. She has not received any recommended vaccines since birth. She attends daycare and remains healthy despite her daily association with several other children for the past 3 months at a home daycare facility. Which of the following phenomena explains why she has not contracted any vaccine-preventable diseases such as measles, diphtheria, or pertussis?
Q24
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?
Vaccines US Medical PG Practice Questions and MCQs
Question 21: A 12-month-old girl is brought to her pediatrician for a checkup and vaccines. The patient’s mother wants to send her to daycare but is worried about exposure to unvaccinated children and other potential sources of infection. The toddler was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines. She does not walk yet but stands in place and can say a few words. The toddler drinks formula and eats a mixture of soft vegetables and pureed meals. She has no current medications. On physical exam, the vital signs include: temperature 37.0°C (98.6°F), blood pressure 95/50 mm Hg, pulse 130/min, and respiratory rate 28/min. The patient is alert and responsive. The remainder of the exam is unremarkable. Which of the following is most appropriate for this patient at this visit?
A. Meningococcal vaccine
B. Gross motor workup and evaluation
C. Rotavirus vaccine
D. Referral for speech pathology
E. MMR vaccine (Correct Answer)
Explanation: ***MMR vaccine***
- The **measles, mumps, and rubella (MMR) vaccine** is recommended for administration at **12-15 months of age**.
- This timing offers protection against these common childhood diseases, which is especially important for children attending **daycare**.
*Meningococcal vaccine*
- The routine **meningococcal vaccine (MenACWY)** is typically recommended for adolescents at **11-12 years of age**, with a booster at 16 years.
- While there are specific circumstances for earlier vaccination (e.g., high-risk conditions), it is **not routine** for a 12-month-old.
*Gross motor workup and evaluation*
- The patient's motor development, standing in place but not yet walking, is **within the normal range** for a 12-month-old.
- A definitive **gross motor workup** would generally be considered if there were more significant delays or regressions.
*Rotavirus vaccine*
- The **rotavirus vaccine** series is typically given at **2, 4, and 6 months of age**, with the final dose administered no later than **8 months of age**.
- A 12-month-old is **outside the recommended age range** for initiating or completing this vaccine series.
*Referral for speech pathology*
- Saying "a few words" at 12 months is **within the normal developmental milestone** for expressive language at this age.
- A referral for **speech pathology** would generally be indicated for more significant language delays.
Question 22: A 3-year-old boy is brought to the emergency room by his mother with fever and difficulty breathing after receiving the BCG vaccine. He has never had a reaction to a vaccine before. He has a history of 2 salmonella infections over the past 2 years. He was born at 35 weeks’ gestation and spent one day in the neonatal intensive care unit. His parents' family histories are unremarkable. His temperature is 101°F (38.3°C), blood pressure is 80/55 mmHg, pulse is 135/min, and respirations are 24/min. On examination, he appears acutely ill. He has increased work of breathing with intercostal retractions. A petechial rash is noted on his trunk and extremities. A serological analysis in this patient would most likely reveal decreased levels of which of the following cytokines?
A. Interferon gamma (Correct Answer)
B. Tumor necrosis factor alpha
C. Interferon alpha
D. Interleukin 12
E. Interleukin 1
Explanation: ***Interferon gamma***
- The patient's history of **recurrent Salmonella infections**, severe reaction to **BCG vaccine** (causing disseminated disease), **fever**, **difficulty breathing**, and **petechial rash** are classic for **Mendelian Susceptibility to Mycobacterial Disease (MSMD)**, a primary immunodeficiency affecting the **IL-12/IFN-γ pathway**.
- **Interferon-gamma (IFN-γ)** is the critical effector cytokine that activates macrophages to kill **intracellular pathogens** like **Salmonella** and **Mycobacteria**. Serological analysis would most likely show **decreased IFN-γ levels** because this cytokine is reduced in most forms of MSMD, whether the primary defect is in IL-12 production, IL-12 receptor signaling, or IFN-γ receptor function (where compensatory production doesn't overcome the functional deficit).
- IFN-γ deficiency explains both the **recurrent Salmonella infections** and **disseminated BCG infection** seen in this patient.
*Interleukin 12*
- **IL-12** is produced by phagocytes (macrophages and dendritic cells) and stimulates **T cells and NK cells** to produce **IFN-γ**. Deficiency in IL-12 or its receptor (IL-12Rβ1 deficiency is the most common form of MSMD) would indeed cause decreased IFN-γ production.
- While IL-12 levels could be decreased in **IL-12 production defects**, this is less commonly the primary finding on serological testing compared to IFN-γ. In the more common **IL-12 receptor deficiency**, IL-12 levels may be normal but signaling is impaired, leading to **decreased IFN-γ as the measurable downstream effect**.
- **IFN-γ** is the more consistently decreased cytokine across different MSMD variants, making it the "most likely" finding.
*Tumor necrosis factor alpha*
- **TNF-α** is a proinflammatory cytokine involved in systemic inflammation, fever, and apoptosis. While it contributes to immunity against intracellular pathogens, primary TNF-α deficiency is not associated with the specific pattern of **recurrent Salmonella infections** and **severe BCG reactions** seen here.
- The clinical picture points to a defect in the **IFN-γ-mediated macrophage activation pathway**, not TNF-α.
*Interferon alpha*
- **IFN-α** is primarily an antiviral cytokine crucial for innate immune responses against viral infections.
- Deficiency in IFN-α typically manifests as severe or recurrent **viral infections**, not the **bacterial/mycobacterial susceptibility** pattern seen in this patient.
*Interleukin 1*
- **IL-1** is a proinflammatory cytokine involved in **fever** and acute phase responses.
- Primary IL-1 deficiency causes impaired inflammatory responses and autoinflammatory syndromes (e.g., IL-1 receptor antagonist deficiency causes systemic inflammation), not the specific susceptibility to **intracellular bacterial infections** characteristic of IFN-γ pathway defects.
Question 23: A 1-year-old immigrant girl presents to her pediatrician for a routine well-child check. She has not received any recommended vaccines since birth. She attends daycare and remains healthy despite her daily association with several other children for the past 3 months at a home daycare facility. Which of the following phenomena explains why she has not contracted any vaccine-preventable diseases such as measles, diphtheria, or pertussis?
A. Genetic shift
B. Tolerance
C. Herd immunity (Correct Answer)
D. Immune evasion
E. Genetic drift
Explanation: ***Herd immunity***
- Herd immunity occurs when a significant portion of the population is immune to a contagious disease due to vaccination or prior infection, providing indirect protection to unimmunized individuals.
- In a daycare setting where other children are likely vaccinated, the presence of immunized individuals reduces the likelihood of transmission to the unimmunized girl.
- This is a classic example of **indirect protection** conferred by high vaccination rates in the community.
*Genetic shift*
- Genetic shift refers to an abrupt, major change in the influenza A virus, leading to new hemagglutinin and/or neuraminidase proteins, resulting in a novel subtype.
- This phenomenon explains the emergence of new pandemic influenza strains, not the protection of an unimmunized child from common vaccine-preventable diseases.
*Tolerance*
- Tolerance in immunology is the failure to mount an immune response to an antigen, often referring to self-antigens.
- It does not explain protection from external pathogens in an unvaccinated individual but rather the absence of an immune response to specific antigens.
*Immune evasion*
- Immune evasion is a strategy used by pathogens to avoid detection and elimination by the host's immune system.
- This concept describes how pathogens survive and cause disease despite an immune response, not why an unimmunized host remains healthy.
*Genetic drift*
- Genetic drift involves small, gradual changes in genes over time, particularly in viruses, leading to antigenic variations.
- While it explains the need for updated vaccines (e.g., annual influenza vaccines), it does not account for the protection of an unvaccinated individual from infection by common vaccine-preventable diseases.
Question 24: 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?
A. The patient’s condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.
B. The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.
C. 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.
D. The patient should receive serogroup B meningococcal vaccination at the age of 10 years. (Correct Answer)
E. 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.
Explanation: ***The patient should receive serogroup B meningococcal vaccination at the age of 10 years.***
- Patients with **sickle cell disease** (SCD) have **functional asplenia**, increasing their risk for invasive meningococcal disease from encapsulated bacteria.
- The **MenACWY vaccine** should be given starting at age 2 months for high-risk children with asplenia, with boosters every 5 years.
- The **MenB vaccine series** is recommended specifically for individuals **10 years and older** with anatomic or functional asplenia, including SCD patients.
- This statement correctly identifies the age-appropriate timing for MenB vaccination according to **ACIP guidelines**.
*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.*
- While SCD patients are at increased risk for meningococcal infections, the **MenB vaccine is not recommended before age 10 years**, even in high-risk patients.
- At age 7, this patient should receive **MenACWY** if not already vaccinated, but MenB vaccination should wait until age 10.
- The timing "as soon as possible" is incorrect for MenB vaccine in this 7-year-old patient.
*The patient's condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.*
- This is completely false. **Sickle cell disease causes functional asplenia**, which dramatically increases the risk of overwhelming sepsis from encapsulated organisms (*S. pneumoniae*, *N. meningitidis*, *H. influenzae* type b).
- Additional vaccinations beyond the routine schedule are **essential and life-saving** for SCD patients.
*The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.*
- This is dangerously incorrect. These vaccines are **specifically recommended and safe** for patients with SCD.
- Patients with functional asplenia are at **highest risk** for invasive disease from these encapsulated bacteria, making vaccination crucial.
- These vaccines do not cause complications or elicit disease in SCD patients; they are inactivated or subunit vaccines.
*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.*
- While SCD patients are at high risk for pneumococcal infection, the vaccination schedule is specific: **PCV13** in infancy, followed by **PPSV23** at age 2 years and older.
- At age 7, if not previously vaccinated, catch-up vaccination is needed, but "as soon as possible" without specifying the proper sequence (PCV13 first, then PPSV23) and "polysaccharide vaccine" alone is imprecise.
- The correct answer focuses on MenB at age 10, which is the most specific guideline-based recommendation among the options.
