Vaccine data CER analysis

Parallel scenario (NOT today's prompt): A person once exposed to tuberculosis bacteria gets a Mantoux skin test. A tiny amount of TB protein is injected just under the skin, and 48 hours later a nurse measures the induration, the firm raised bump, in millimeters. A second person who has never been exposed to TB gets the same test. The results table shows: exposed person, 15 mm of induration; never-exposed person, 0 mm. Read the data and write a CER about immune memory.\n\nClaim: The skin-test data show that the previously exposed person carries lasting immune memory for the TB bacteria, while the never-exposed person does not.\n\nEvidence: At the same 48-hour reading, the exposed person developed 15 mm of induration at the injection site. The never-exposed person developed 0 mm of induration under identical test conditions.\n\nReasoning: The first exposure to TB caused the immune system to make memory T cells specific to that bacterium. When the test reintroduced the TB protein, those memory T cells recognized it and triggered a fast, localized response that pulled immune cells and fluid into the area, producing the firm 15 mm bump. The never-exposed person had no matching memory T cells, so nothing recognized the protein and no reaction formed, which is why the induration measured 0 mm. The difference in millimeters is the visible signature of cell-mediated immune memory: a measurable reaction means the body has met this antigen before.\n\nLimitation: A single induration measurement shows that memory exists, but it does not reveal how strong the protection is or how long it will last, and it cannot by itself distinguish past infection from a prior TB vaccine. Reactions can also vary from person to person, so one reading is not proof of full immunity.