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ajnozari t1_ixtpmtb wrote

Reply to comment by imalmostshy in How soon after exposure is the flu contagious? by AcJc_0604

Typically your non-covid viruses. Flu A/B, rhinovirus, adenovirus, parainfluenza, etc.

Covid has been shown to be shed with high variability between individuals and so the best way is a covid PCR test that actually checks for the virus. That said if you no longer have a fever that’s a good indicator that your body has fought off the offending agent (in most cases).

In immune competent individuals this means you have circulating antibodies that should inactivate the virus as it exists the cells and target it for destruction.

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kbotc t1_ixv7f1v wrote

PCR’s are incredibly sensitive, so you want to be sure you can see the cycle count. PCR doesn’t check for the virus, It checks for viral RNA fragments, which can be shed for months after you are contagious. That RATs actually are looking for certain surface proteins, binding to them, then that is what is deposited on the positive line. The BinaxNOW tests will flip positive if there’s the N (Neuclocapsid) protein in your nose, which is a certain sign COVID is actively reproducing in your airways.

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EllieGeiszler t1_ixwraee wrote

Does the protein BinaxNOW tests for differ from what Flowflex tests for? I don't trust BinaxNOW because I've never gotten a positive on them despite having had Covid twice now as confirmed by several days in a row of positive Flowflex tests. If they test for different proteins then that would explain it...

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kbotc t1_ixx2jgj wrote

They test for the same protein.

I’m hesitant to recommend the Flowflex just because they had a massive counterfeit problem: https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/counterfeit-home-otc-covid-19-diagnostic-tests#diagnostic

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