Why does vaccine effectiveness against a rapidly mutating virus, such as influenza, wane over time despite initial high antibody titers?

💡 Explanation

Vaccine effectiveness decreases with viral mutation because affinity maturation of B cells is required to maintain high affinity antibodies that can neutralize new viral variants; therefore, the original antibodies lose effectiveness, rather than being maintained indefinitely or T cell responses being primarily responsible.

• If an elderly patient exhibits reduced muscle strength and bone density following hip replacement surgery, which mechanism primarily explains the co-occurrence of these seemingly distinct symptoms?
• If a patient has chronic pain, which outcome is likely if descending modulation via the periaqueductal gray (PAG) and rostral ventromedial medulla (RVM) is impaired?
• Why does an elderly patient with diminished kidney function and reduced sensitivity to thirst experience a higher risk of dehydration when prescribed diuretics for hypertension?
• What causes medullary hypertonicity in the kidney's countercurrent multiplier system?
• Which outcome occurs when prolonged hyperglycemia persists in a system?
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