A 9-month-old infant received an inactivated polio vaccine (IPV) today. Which of the following best describes the immune response expected from this vaccine compared to the oral polio vaccine (OPV)?
A) IPV induces stronger mucosal immunity than OPV
B) IPV and OPV provide equal systemic and mucosal immunity
C) OPV primarily induces mucosal immunity, while IPV induces systemic immunity
D) IPV is superior in generating herd immunity compared to OPV
✅ Correct Answer: C) OPV primarily induces mucosal immunity, while IPV induces systemic immunity
Explanation: OPV is a live-attenuated vaccine that replicates in the gut, inducing strong mucosal (IgA) immunity and reducing viral shedding, which helps in herd immunity. In contrast, IPV is an inactivated vaccine that primarily induces systemic immunity (IgG) but does not provide significant mucosal protection. This distinction is crucial in polio eradication strategies.
📖 Source:
● World Health Organization (WHO). "Poliomyelitis: Immunization, Vaccines, and Biologicals." WHO, 2023
A 6-month-old infant received an early dose of the MMR vaccine due to an ongoing measles outbreak. What is the best course of action regarding future MMR doses?
A) A second MMR dose is needed at 12 months, followed by a routine booster at school age
B) No additional doses are required if seroconversion is confirmed at 9 months
C) The early dose counts toward the routine schedule, and only one more dose is needed at 18 months
D) The child should receive two more doses at 12 and 18 months because maternal antibodies may have interfered with the early dose
✅ Correct Answer: D) The child should receive two more doses at 12 and 18 months because maternal antibodies may have interfered with the early dose
Explanation:
MMR given before 12 months may have reduced efficacy due to maternal antibodies neutralizing the live virus. Therefore, the early dose does NOT count toward the routine immunization schedule, and the child should still receive two additional doses at 12 and 18 months for optimal immunity.
📖 Source:
● Centers for Disease Control and Prevention (CDC). "Measles, Mumps, and Rubella (MMR) Vaccination Recommendations." CDC, 2023
A 2-month-old infant receives the first dose of the DTaP vaccine. Which of the following factors significantly increases the risk of developing a hypotonic-hyporesponsive episode (HHE) after vaccination?
A) Preterm birth at 33 weeks gestation
B) Family history of febrile seizures
C) Maternal history of Guillain-Barré syndrome
D) Prior administration of paracetamol before vaccination
✅ Correct Answer: A) Preterm birth at 33 weeks gestation
Explanation: HHE is a rare adverse reaction characterized by sudden hypotonia, pallor, and unresponsiveness after vaccination, most commonly seen after DTaP in infants <6 months old. Preterm infants (<37 weeks) are at higher risk due to immature autonomic regulation. Family history of febrile seizures and maternal Guillain-Barré syndrome do not increase HHE risk, and paracetamol does not contribute to its occurrence.
📖 Source:
● American Academy of Pediatrics (AAP). "DTaP Vaccine: Adverse Events and Safety Considerations." AAP, 2022.
A 7-year-old child who has never received any vaccines presents for catch-up immunization. Which of the following vaccines should NOT be administered?
A) Tdap
B) MMR
C) Rotavirus
D) Inactivated Polio Vaccine (IPV)
✅ Correct Answer: C) Rotavirus
Explanation: The rotavirus vaccine is only given to infants, with a maximum age limit for the first dose at 14 weeks and 6 days, and the final dose must be completed by 8 months of age. MMR, IPV, and Tdap can be given as part of a catch-up schedule.
📖 Source:
● Centers for Disease Control and Prevention (CDC). "Catch-up Immunization Schedule for Children and Adolescents Aged 4 Months–18 Years." CDC, 2023
A 5-year-old child with acute lymphoblastic leukemia (ALL) in remission is due for MMR and varicella vaccines. What is the best approach?
A) Administer both vaccines immediately
B) Administer only the inactivated vaccines
C) Postpone MMR and varicella until 3 months after chemotherapy ends
D) Give varicella but delay MMR
✅ Correct Answer: C) Postpone MMR and varicella until 3 months after chemotherapy ends.
Explanation: Live vaccines (e.g., MMR and varicella) should not be administered during chemotherapy or within 3 months of completing immunosuppressive therapy due to the risk of uncontrolled viral replication. Inactivated vaccines can be given, but they may have reduced efficacy during immunosuppression.
📖 Source:
● American Academy of Pediatrics (AAP). "Immunization in Immunocompromised Children: Guidelines and Recommendations." AAP, 2023.
● Infectious Diseases Society of America (IDSA). "Vaccination of the Immunocompromised Host: Best Practices." IDSA, 2022