Biotechnology
A PCR test can call you positive weeks after you stopped being infectious. That is the test working correctly
2 Sept 2026 · 8 min read
PCR is a photocopier for one chosen stretch of DNA, and it doubles what it finds thirty times over. Almost everything people find confusing about the test — the lingering positives, the Ct number, the false negatives — is a direct consequence of that.
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