Question

antibody titer

	day 1	day 7	day 14	day 21
patient a	0	0	256	512
patient b	128	256	512	1024
patient c	0	0	0	0
patient d	128	128	128	128

in table 18.1, who is most likely protected from the disease, as observed by the test results over time?
a patient a
b patient c
c patient d
d patient b

Explanation:

Step1: Analyze antibody titer trends

Antibody titers indicate immune protection; higher/stable titers suggest protection. Patient A: increasing (0→512, late response). Patient B: steadily increasing (128→1024, consistent rise). Patient C: 0 (no immunity). Patient D: stable 128 (no increase).

Step2: Compare protection likelihood

Patient B has the highest and continuously rising titers, showing robust immune response.

Answer:

D. Patient B