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reddiart12 t1_ixt4qzz wrote

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

May I know, in terms of detection (which I assume works by viral load), does that mean if I’ve just been exposed to a COVID-positive person, even if I take the ART test right away, it’s likely the results will not show I’m infected? If so, how long should I wait (not in terms of beginning to quarantine) before taking an ART test assuming I’m suspicious I’ve infected, before the test is accurate/have reliable results?

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Samilynnki t1_ixt89in wrote

24-48 hours post suspected exposure is the generally accepted minimum wait time to have a sufficient viral load for a rapid test to be accurate. 72 hours post exposure is considered ideal for testing. I appreciate you clarifying/implying that you would obviously be quarantining from the time of suspected exposure, for the health and safety of others, even if a rapid test couldn't give you an accurate result in the first day or so.

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TreeKlimber2 t1_ixuqyvc wrote

According to the CDC, you need to wait 5 days unless symptomatic. Earlier tests are likely to come back negative even if the person is carrying the virus.

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Samilynnki t1_ixvbgsw wrote

since when? I am an RN and did one of the mass COVID testing sites in my town (back in 2021) and later one of the mass COVID vaccine clinics.

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TreeKlimber2 t1_ixwp30r wrote

...and I work for the Department of Health. Waiting has been the standard for awhile now.

https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/testing.html#when-to-get-tested

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Samilynnki t1_ixwqezq wrote

Ah, yes I see that page was updated September 2022. That would be after 2021, which I specified was the time I was doing the swabs and later the vaccines.

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TreeKlimber2 t1_ixwrk67 wrote

That was a page update; the recommendations to wait before testing have been in place for quite some time now. Though they were somewhat recently changed from waiting 4 days to the current standard.

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[deleted] t1_ixttsue wrote

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GreatAndPowerfulNixy t1_ixtzql5 wrote

Rapid antigen tests have high rates of false negative results. Repeat testing is needed to confirm.

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kbotc t1_ixv6ban wrote

While true, they’re quite effective for point in time “am I contagious at this second”

If you’ve got antigens in your nose, you are shedding.

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fastolfe00 t1_ixuog2z wrote

Rapid antigen tests commonly give false negatives. They are better thought of as tests to prove you have COVID, not tests to prove you don't. You need multiple tests if you're sick and want to be sure it's not COVID. Time is only part of it.

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TreeKlimber2 t1_ixurdoz wrote

Actually, your experience is spot on. It's recommended to wait 5 days to test if not symptomatic sooner. Earlier tests are not expected to accurately detect the virus.

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[deleted] t1_ixtkq3m wrote

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AnthraciteRoad t1_ixt89lo wrote

If you get to day 5 with no symptoms and with negative rapid tests on days 4 and 5, you probably aren't infected. Two negative tests after the onset of symptoms means the symptoms probably aren't from COVID.

A positive test at any point means you probably are infected.

A single negative test, or any number of negative tests before day 5 in the absence of symptoms, is inconclusive.

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ajnozari t1_ixt833j wrote

Typically if you have a fever you’re considered contagious. Once the fever ends you’re still possibly contagious for up to 72-96 hours, depending on how much virus you’re shedding and how much mucus you’re shedding.

However the best way to be sure to not spread it should you have to go out is a mask. The goal is droplet containment more than anything. Remember say it don’t spray it is truth.

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imalmostshy t1_ixthg8m wrote

Is this in reference to Covid-19, or general respiratory infection/cold?

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ajnozari t1_ixtpmtb wrote

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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the-truthseeker t1_ixwtxni wrote

I do want to thank everybody here for listing the information about covid, but remind that the question was asking about the flu.

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iksbob t1_ixt9apo wrote

Correct. The virus needs time to multiply before it will show up on an antigen test. ART tests are a reasonable gauge of how infectious you are. If you were exposed mere hours before, you are not yet infectious and so will not register as infected. An exception being if you were just exposed to a massive dose of the virus, such that there is a substantial amount of the virus trapped in the mucous in your nose.

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