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Related: Editorials & Other Articles, Issue Forums, Alliance Forums, Region ForumsHow long after exposure before you will test positive? What say you Harvard Medical School?
Harvard Medical School - If you've been exposed to the virus*snip*
What are the chances that a coronavirus test will tell me I am not infected when I actually am?
The chances that a coronavirus test will give you a false negative (indicating that you are not infected when you actually are infected) depend upon the type of test you have and when in the course of your infection the test is performed. There are two main types of tests:
nasal/throat swab tests and saliva tests, both of which detect the virus itself
blood tests that detect antibodies that your immune system produces in response to the infection.
If you get the nasal/throat swab or saliva test, you will get a false negative test result:
100% of the time on the day you are exposed to the virus. (There are so few viral particles in your nose or saliva so soon after infection that the test cannot detect them.)
About 40% of the time if you are tested four days after exposure to the virus.
About 20% of the time if you develop symptoms and are tested three days after those symptoms started.
This possibility of a false negative test result is why anyone who has symptoms that could be due to COVID-19, or has been exposed to someone known to be infected, must isolate even if they test negative for coronavirus.
The blood antibody test does not become positive (or might never be positive in some people) until many days after exposure, and is therefore not the primary test used for diagnosis. It is very useful for research and public health decision making.
*snip*
So, is Barr self-isolating? Asking for a friend.
captain queeg
(10,184 posts)I guess she has tested negative twice but the docs say her symptoms are so classic they are sure she has it. I dont know how much time elapsed from when she stated feeling it and got tested. Or the second test. She hasnt been severely ill yet; dry caugh, no sense of taste and smell is all Ive heard of.
still_one
(92,184 posts)still be adhered to.
It is highly unlikely that any vaccine will be 100% effective, and until the level of sars co v2 is down to low levels, and herd immunity is established, it would be prudent to continue following social distancing and masks
Johonny
(20,840 posts)I was sort of thinking I might wear a mask in public from now on. I'm not a big fan of being sick and I can't be the only father of small kids that has noticed the much healthier lifestyle social distancing, washing hands, and masks has brought to our house
still_one
(92,184 posts)demosincebirth
(12,536 posts)still_one
(92,184 posts)dixiegrrrrl
(60,010 posts)because the quick test is the blood one
Seems there really is no reliable test for it until too late in the game.
which applies to those fever checks, too.
Jamastiene
(38,187 posts)So, those people trying to claim well Herman Cain was tested right after the rally are full of it. He wouldn't have tested positive yet. The incubation period would have been longer. So, those "after" tests they keep claiming at the Tulsa rally were a waste of time and really show how ignorant everyone in Trump's campaign really are. It also shows just how ignorant at least all of his supporters who were present and who are using that as some excuse to defend him, really are too. But, then, we already knew that.
frazzled
(18,402 posts)You shouldn't even bother getting tested until at least three days after you have actual symptoms. (At which point you probably feel too ill to go get tested.) Otherwise, just keep self-isolating if you think you may have been exposed in any way (which is every time you go to the grocery I guess). This is pretty much what we've been doing anyway.
This was sort of the protocol at the beginning of the pandemic, when only symptomatic people were told to get tested. Are we going in circles?
ON EDIT: It seems that people really shouldn't get tested until symptoms, because otherwise a false negative will lead to a false sense of security and possible spread.
LizBeth
(9,952 posts)at two or three days, ... But, it may be that contagious is not until well after tested positive. Something I have not seen anywhere. Do we know?
Evergreen Emerald
(13,069 posts)That is the period one is contagious.
LizBeth
(9,952 posts)Thanks much for the information. I didn't want to hunt and read