Covid Test Types and Accuracy

Did I miss something? What does PCR stand for? Maybe I know it by a different name. I also have been wondering about accuracy--the number of false positives and the number of false negatives.

Simplest Terms: https://www.webmd.com/lung/qa/what-is-a-pcr-test

PCR error rates are incredibly low.

A given PCR test for a given virus may have low error rates, depending on the protocols of the lab and the technician operating it.

Translating that result into safe, effective, and prudent health advice for an individual or a population is another question.

I have been getting PCR-tested weekly at work, but I don't think I would bother myself even if it was free. There are other things we could all do that would yield direct health benefits.

Speaking of which, the sun just came out here, so I will go make some vit D.

Or work out your big muscle group. I read that they release "things" that help increase immunity.

It is truly disheartening to come to an engineering forum and find so many posts that leave me feeling like I've inadvertently stumbled onto the medical/scientific analog to the Flat Earth Society, Racist Division. The conspiracy required to have medical experts (real ones; not basement internet mouth breathers) across the entire country singing the same tune, is impossible, on its face. Surely the deniers have friends or relatives that work in the medical field. Have they not asked the medical professionals they trust about the real dangers? About the massive overload on the health care system because there are so many science-deniers who feel it's their right to infect others?

The reality is that if everyone had followed sensible science advice (before the CDC and others were neutered by the politician/cult leader currently in power), we likely would never have had to shut down in the 1st place. Instead, we get nut-case members of Congress who've contracted the virus, saying that they only got it because they breathed into their own mask.

At least the followers of Jim Jones only killed themselves and their children (and a few well meaning political figures who went to investigate). Our current cult leader has managed to kill not only his followers, but better than a hundred thousand innocent people who couldn't get out of the way of his runaway train.

Charlie

Since you bring science into the discussion - we're mostly all science minded people here, so we can talk about science - my question is simple.

Modern medicine is based on science, correct? If so, then medical experts should be able to determine if wearing a mask will reduce the chance of spreading an airborne virus like Covid 19. I think the majority of medical experts will agree that wearing a mask does reduce the infection rate, however wasn't is a doctor who came out very early in this pandemic and stated that people shouldn't wear a mask?

I'll ask another question, since you brought politics into the discussion. A well know governor wanted to scare people into conforming. He brought a young gal in her early 30's up to the podium and asked her to tell the story of her late husband's Covid related death. That poor girl was crying and our governor made her feel so much pain from her loss - the purpose was to scare people. Look, if a healthy 30 year old male can die from this, then every one of you will die if you get Covid! That's what he was trying to do. Yet he's enjoying a fun birthday party at a >$300 per plate restaurant and of course there's no social distancing. Yes, he's apologized for his careless act, so we've all forgiven him, right?

A handful of countries have been able to control Covid. Most countries with contemporary idealogy (like us) have done a poor job controlling it.

Is it the leadership of the country? Maybe, but I don't think you can blame so much of it on him/her.

Is it the genetic make up of the people? No, because some countries are very homogeneous, while others are a true mish-mash, like us.

Maybe it's the culture? Get it. I don't think it would've made a whole lot of difference if our last POTUS was in charge, because our culture believes in freedom and in our hearts, we don't feel we should be told what to do. We can be tricked into it or made to feel guilty, so we toe the line. Or we can truly understand and make the decision ourselves. Very few of us follow like robots. Heck, even in China they don't. They're threatened and thrown in jail - remember the video's of the "virus police" breaking into homes and taking people out?

Okay, back to the topic, which is related to the accuracy of tests and which one we should trust - or should we trust any?

If the rapid test is 50% accurate then this doesn't make sense.

2020/11/20/nyc-restaurant-requires-guests-take-50-rapid-coronavirus-test-entering/

If successful, this could set a new precedence for entry into private businesses.

For me, it would have to be one heck of a great restaurant for me to pay a $50 cover charge and to allow them to stick a Q-tip up my nose!

The covid virus seems to reach peak infectious level between 4 and 7 days, before and after that the transmissibility falls off sharply...also the test results are nearly 100% accurate during this peak period...which is what we should be concerned with...

I don't know if I'm not analyzing this properly, but here goes.

1. The purpose of testing is to determine if a person has Covid.

2. I'm going to assume the reason why we want to know if someone has Covid is to keep them isolated, so they don't spread it.

3. So if we consider both 1 and 2, the test should either confirm or deny the need to isolate.

Based on the three items above, the linear chart may or may not be the best to use. The test should try to find out if the person has enough Covid virus in him to make him a risk for others to be around. On the log scale, I believe the threshold number is easier to see. On the linear scale, the virus load increases so rapidly that the time the person becomes contagious may be hard to determine.

Though I do like how he breaks down the linear vs log chart. He just didn't discuss where the threshold for contagiousness comes in.

Thanks for the video.

We should also consider the error rates. As I understand it, the quick test has higher error rates than the test (PCR?) that takes about 3 days. In addition, the false positive and false negative rates might be different.

Then, are they testing because symptoms have appeared, which would naturally have higher positive outcomes, or are they testing whoever wants it whether symptomatic or not?

The statistics folks should have fun with this even if the rest of us aren't.

I've been told that the PCR test is the one you should use (swab up the nose), because of the accuracy. The quick test has much lower accuracy.

I don't hear this discussed much, but your point on the reason for the test is crucial. If we think about why people are tested, it can sway the results.

1. A person feels they have it. There will be a higher false negative rate. There will be a lower false positive rate.

2. A person must be tested per their job. There will be a lower false negative rate. There will be a higher false positive rate.

3. A person feels they may have been exposed and would like confirmation. This is a tricky one and depends on factors like the rate of infection in the community, how much exposure the person had, health of the person and if the person had Covid and was asymptomatic.

I like how you added this unknown to the accuracy of testing.

ADMIN note

This post has been redacted for political content.

Ok I'm a little put out that this is post 108 and I haven't been moderated for being political.

I must be slipping, or not.....

Patience,... there’s still time, the day is not over yet,...

Back to testing!

Anyone have something new to add?