A 75-Year-Old Man Is Hospitalized Due to Respiratory Distress

A 75-year-old man is hospitalized due to respiratory distress.  The patient developed fever, cough, and muscle aches 4 days prior to admission.  He is otherwise healthy and has no chronic medical conditions.  The patient has received all recommended vaccinations, including a yearly flu vaccine.  Temperature is 39 C (102.2 F) , blood pressure is 110/65 mm Hg, pulse is 115/min, and respirations are 29/min.  Chest x-ray shows bilateral infiltrates.  Reverse transcriptase PCR of a specimen from a nasopharyngeal swab reveals a strain of influenza A virus that was included in the seasonal trivalent flu vaccine.  The patient lives with his 50-year-old son, who received the same vaccine but did not develop the infection.  Which of the following factors most likely increased this patient's risk of vaccine failure compared with that of his son?

A) Decreased overall quality of antibodies
B) Decreased production of naive B lymphocytes
C) Diminished levels of memory T lymphocytes
D) Increased apoptosis induced by neutrophils
E) Increased phagocytosis by macrophages

Correct Answer:

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