If you test negative for COVID, you often still have COVID. the PCR tests are only 80% accurate in optimal scenario (only 80% of infected people actually test positive, on the peak viral count day of infection, so the practical accuracy is more like 60%)
source on this? especially the numbers. My understanding was PCRs are typically very sensitive, and tend to stay positive for far longer than people are actively experiencing symptoms or contagious, which doesn’t line up with you saying “80%” on the peak viral count day of infection.
What I’m seeing is confirmed false negative rates somewhere below like 5%, though mostly studies from earlier in the pandemic.
source on this? especially the numbers. My understanding was PCRs are typically very sensitive, and tend to stay positive for far longer than people are actively experiencing symptoms or contagious, which doesn’t line up with you saying “80%” on the peak viral count day of infection.
I don’t know for sure, but I suspect they are citing this link, which says “… In these studies, clinical performance ranges and approaches 80% sensitivity and 98-99% specificity when using a good comparator…”
An 80% sensitivity means that if you have COVID, you have a 20% chance of a false negative (i.e., testing negative despite being positive). Let’s say you test everyday for 4 days; the odds of getting all false negatives is 1/(5^4), or 1/625, or 0.16%.
A 98% specificity means that someone without COVID has a 2% chance of a false positive (i.e., testing positive despite not being sick). PCR’s are imperfect, but afaik they are the gold-standard test. They are widely available, and have the most science backing their use.
They also suggested that tests completed at-home are 50% accurate, which doesn’t seem like it’s based on any scientific findings I can find. For example, this study found that tests completed at home are equally as sensitive (>83%) and specific (>99.5%) as tests completed by doctors. But I could be wrong.
That person also mentioned stool tests are the best for screening for COVID-19, but I’m not sure what that is all about, and research comparing stool tests to other measures doesn’t seem to support the accuracy of stool tests over others… I understand much of their concern and skepticism - I don’t take people in my life saying things like “Sure I’m sick but I tested negative so it’s just a cold” seriously. I get very frustrated when I hear that shit. That being said, I am a bit sus about the specific things they are recommending or saying in this thread.
source on this? especially the numbers. My understanding was PCRs are typically very sensitive, and tend to stay positive for far longer than people are actively experiencing symptoms or contagious, which doesn’t line up with you saying “80%” on the peak viral count day of infection.
What I’m seeing is confirmed false negative rates somewhere below like 5%, though mostly studies from earlier in the pandemic.
Rapid tests are straight trash though
I don’t know for sure, but I suspect they are citing this link, which says “… In these studies, clinical performance ranges and approaches 80% sensitivity and 98-99% specificity when using a good comparator…”
An 80% sensitivity means that if you have COVID, you have a 20% chance of a false negative (i.e., testing negative despite being positive). Let’s say you test everyday for 4 days; the odds of getting all false negatives is 1/(5^4), or 1/625, or 0.16%.
A 98% specificity means that someone without COVID has a 2% chance of a false positive (i.e., testing positive despite not being sick). PCR’s are imperfect, but afaik they are the gold-standard test. They are widely available, and have the most science backing their use.
They also suggested that tests completed at-home are 50% accurate, which doesn’t seem like it’s based on any scientific findings I can find. For example, this study found that tests completed at home are equally as sensitive (>83%) and specific (>99.5%) as tests completed by doctors. But I could be wrong.
That person also mentioned stool tests are the best for screening for COVID-19, but I’m not sure what that is all about, and research comparing stool tests to other measures doesn’t seem to support the accuracy of stool tests over others… I understand much of their concern and skepticism - I don’t take people in my life saying things like “Sure I’m sick but I tested negative so it’s just a cold” seriously. I get very frustrated when I hear that shit. That being said, I am a bit sus about the specific things they are recommending or saying in this thread.
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speaking from my experience in canada, so my bad haha. at least in my area, anyone can take a pack from any pharmacy whenever they want
Talking about PCR tests here