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KauaiCat t1_ixsuar8 wrote

No, they are not immediately contagious. It could take days to become contagious.

Initially the virus multiplies unchecked and it reaches a peak concentration. This is when you are most contagious. Shortly after reaching peak concentration, you begin feeling symptoms as the immune system has realized it is under attack. Normally by the time you feel symptoms the concentration of the virus in your body has already begun to decrease thanks to the immune response.

This is true of influenza and many other viruses. The time it takes between you getting infected and symptom onset is called the incubation period and it's normally more than 24 hours for influenza.

For Covid-19 the average incubation period is several days, but you could be spreading the virus for 24 hours or a little longer before you first feel symptoms.

You feel fine, but you are highly contagious. Because you feel fine you are likely to be near people and talking to them in close proximity. This is where the virus shines. As you speak, microscopic spit balls filled with virions are floating through the air and those nearby are breathing them in.

Emergency rooms will normally see an spike in influenza this time of year in the US. A few days after friends and family congregated closely together for Thanksgiving.

Edit: Peak concentration is typically reached *shortly after feeling symptoms* rather than shortly before as stated above.

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reddiart12 t1_ixt4qzz wrote

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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SirNanigans t1_ixtdwci wrote

Could we make a big difference by encouraging people to reduce contact with others for a couple days after being part of a get together or large, packed event?

Even if it doesn't mean a quarantine, just not going right from one social event to another and saving the next shopping trip for a couple days after you get back should have an impact on virus spread, right?

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JarasM t1_ixtx6fp wrote

I don't see people doing that without a quarantine, especially since the difference between that and a quarantine is very subtle.

Plus, I imagine this wouldn't work well. Okay, after a packed event you're supposed to avoid crowds. So you individually meet several friends and infect them. None of them are inclined to quarantine, since they haven't been to any packed events like you, so they're free to go to any packed events they choose. They go and spread the virus just the same as if you'd go. To make a dent to overall infection rates you need to mask up and limit packed events altogether.

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mattsl t1_ixtxn6q wrote

You were able to logic out the need for the mandates and restrictions in a single short paragraph, yet here we are nearly 3 years in and people still don't understand.

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SirNanigans t1_ixugse7 wrote

>meet several friends and infect them. None of them are inclined to quarantine

I don't know if it would be helpful or not, but this argument is a little questionable. You have seen several friends rather than a second gathering, reducing the number of people you infect. Plus you implied that someone cannot opt to see nobody in a social manner for the two days.

Who knows, it could be a waste of time still, but I would give it a little more credit.

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RedSteadEd t1_ixt5tjj wrote

... which is why we need mask mandates.

Thank you for coming to our joint presentation on the matter.

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OsiyoMotherFuckers t1_ixtv06y wrote

Follow up to this:

It takes about 2 weeks for the flu vaccine to take effect. It’s too late for thanksgiving, but folks might consider getting the flu shot by December 11th to have full vaccine protection by Christmas.

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trowawaid t1_ixvlrsd wrote

Anyone reading this and debating: do it.

I put off getting my vaccine and got the flu right before Thanksgiving :/

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Seicair t1_ixt8t5f wrote

So, if you visit two thanksgiving gatherings, and you’ve seen none of the people involved in weeks, your odds of transmitting a contagious disease from one gathering to another is very low to nonexistent?

I suppose that would depend on fomites on clothing and such, wouldn’t it.

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chaoticneutral t1_ixudt9s wrote

That depends on the virus, but generally speaking, COVID and other respiratory viruses don't seem to survive longer than 3 days on surfaces in ideal conditions and degrade much, much faster in the natural environment. There is even some evidence your skin naturally serves somewhat of a disinfectant and kills flu virus pretty rapidly ( https://academic.oup.com/cid/article/48/3/285/304169).

That being said, you should still wash your hands.

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thosewhocannetworkd t1_ixujgfm wrote

So if people caught influenza during Thanksgiving on Thursday, would it be a bad or typically higher risk move to go out to eat Saturday (today) night after Thanksgiving because most of the infected are now at peak concentration, timeline wise, but not feeling their symptoms yet? Or was yesterday the worst day to go out, because today they’ll wake up feeling ill? Asking cuz have dinner date tonight and concerned about influenza

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KauaiCat t1_ixuqyeg wrote

There is a statistical distribution for all of these time periods and a lot could depend on things like the infectious dose you received, your immune system's abilities, the particular strain of the virus, how susceptible your cells are to infection with the virus (e.g. do your cells have a high concentration of the receptor the virus is looking for to gain access to your cells?), etc.

I said "Shortly after reaching peak concentration, you begin feeling symptoms", but this is not correct.

Typically peak concentration would hit shortly *after* feeling symptoms rather than before. However, you will be highly infectious a up to several hours before feeling symptoms for influenza.

The high probability zone of being being contagious before symptoms is somewhere around 36-48 hours after exposure for influenza, but someone below mentioned that it could be much shorter for influenza B.

This is just where most people will be contagious. It's possible you would be contagious 24 hours after exposure or not until 72 hours or more.

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Bxsnia t1_ixw4ue2 wrote

Why do people go to the emergency for the flu? Older people get vaxxed, and younger people are expected to just deal with it for a few days where I'm from.

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moonkittiecat t1_ixttn2f wrote

I started showing symptoms last Sunday (coughing, fever, congestion). What makes this turn into pneumonia? Why do I still have a fever off and on? (I'm on plenty of medicine from the doctor).

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