A 12-year-old boy... recurrent episodes of epistaxis... anterior bleeding within the Kiesselbach plexus... Which of the following is the most appropriate initial step?

Correct Answer: C

Rationale: Direct pressure to the nose stops most anterior epistaxis (Kiesselbach plexus) as the initial step. Packing (B) or cautery (D) follows if pressure fails. Option A is incomplete.

Correct Answer: C

Rationale: Epinephrine is the first-line, immediate treatment for anaphylaxis, administered intramuscularly (e.g., via EpiPen) to reverse airway constriction, hypotension, and other life-threatening symptoms by stimulating alpha- and beta-adrenergic receptors. Choice A (Benadryl, diphenhydramine) and D (Reactine, cetirizine) are antihistamines used as adjuncts to reduce itching and hives but do not address acute airway or cardiovascular collapse. Choice B (Gravol, dimenhydrinate) is an antiemetic, irrelevant to anaphylaxis.

Correct Answer: C

Rationale: Tetanus, caused by *Clostridium tetani*, is not spread person-to-person. It is acquired through environmental exposure (e.g., wound contamination with soil containing spores), not respiratory or direct contact. Meningococcal (*Neisseria meningitidis*), tuberculosis (*Mycobacterium tuberculosis*), and influenza Type B (*Haemophilus influenzae* type b, despite its name) are transmitted person-to-person via droplets or respiratory secretions, making Choice C the exception.

Correct Answer: D

Rationale: An attenuated vaccine contains a live but weakened (attenuated) virus or bacteria that replicates minimally in the host, stimulating a strong immune response without causing disease (e.g., MMR, varicella). Choice A describes inactivated/killed vaccines, Choice B refers to combination vaccines (not attenuation), and Choice C describes toxoid vaccines (e.g., tetanus), making Choice D the correct definition.

Correct Answer: C

Rationale: Per CDC guidelines, a 6-month-old at a routine visit receives RV (rotavirus, dose 3 if RotaTeq), DTaP (dose 3), Hib (dose 3), PCV (dose 3), and IPV (dose 3). HepA starts at 12 months, MMR and Varicella at 12-15 months, and influenza annually starting at 6 months (but requires 2 doses 4 weeks apart initially, not fully captured here). HepB dose 3 is typically at 6-18 months but often given earlier (e.g., birth, 1-2 months, 6 months). Choice C is the most accurate standard set without overcomplicating the schedule.