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Originally posted by rontuner:
Correct me if I'm wrong, but I read somewhere that the rapid test will determine if a person is infectious, not whether they are infected. That explained to me why someone often gets a negative result from the quick test, only to test positive later on.

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So here's the question:
Family A is hosting xmas day. Big house. None of them (parents and 5 kids, grade school through high school) are vaccinated, but most of them had Covid after thanksgiving 2020. Reasonably sure all other families attending are vaccinated and boosted if they are due. Is the danger primarily to the hosting unvaccinated family, or is it an increased risk to all attending?

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Sounds like from your contract tracing that all are at risk because you've been following many vaccinated folks getting sick...

There might be a couple of dozen people there.

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Originally posted by wtg:
There were many sources that were consistent in their explanations of the various tests; I chose two that I thought summarized the information well.

Here's a full explanation from UC Davis Health:

https://health.ucdavis.edu/hea...ts-explained/2020/11

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Unlike some other testing protocols, [the university] uses a quantitative PCR test. The cycle cutoff for a positive result corresponds to about 1,000 viral copies per milliliter, which is recommended by the CDC. Some false negatives may be seen at the very early stages of infection when the viral load is low; however, false positives are almost nonexistent.

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We don't have spit tests here. I would be surprised if they are reliable. Why would anyone get their brain swabbed if they could just spit?

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Originally posted by piqué:

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Originally posted by wtg:
There were many sources that were consistent in their explanations of the various tests; I chose two that I thought summarized the information well.

Here's a full explanation from UC Davis Health:

https://health.ucdavis.edu/hea...ts-explained/2020/11

Thanks for the additional info. Not all communities have all these options. We are a very rural state with limited resources. Also, each county follows its own rules and protocol. YMMV.

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Originally posted by ShiroKuro:
In response to Pique's responses to my questions above (re types of tests, diff b/w PCR and antigen tests etc.) I googled around and found more info about my university's covid test and so on, including this:

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Unlike some other testing protocols, [the university] uses a quantitative PCR test. The cycle cutoff for a positive result corresponds to about 1,000 viral copies per milliliter, which is recommended by the CDC. Some false negatives may be seen at the very early stages of infection when the viral load is low; however, false positives are almost nonexistent.

So our spit tests are still PCR tests.  

Also, pique, you mentioned the length of time it takes to get test results back, but I don't think that's a good gauge since time to results will be heavily influenced by local/environmental details.

Our uni conducts tests on campus and processes results on campus. Total turn around time, from when I submit my sample to when I get the automated test results via cellphone app, is almost always less than 24 hours, sometimes more like 4 hours. I doubt other places have this kind of turn around time. But also, the fact that we have this fast turn around is not an indication of a low quality test. It's an indication of a system that works really, really well, on a population that is constant in terms of numbers -- iow, the university testing center only tests the university population (all students, faculty, staff and employees of any type). That's a pretty big number, since this is a big school, but it's a fixed number that never changes. Once you run the numbers, you figure out how many tests you need to process per week, per day, then you put the system in place and let it run. I saw that at the beginning of the semester when the turnaround time for results sped up after maybe the second or third week. Since then it's been mostly the same.

Also, btw, every step of the testing process here has been designed by uni employees and researchers, even including the cellphone app we use to sign up for a test slot and receive test results. And the testing center is staff by university researchers and grad students as well. 100% in-house, as it were.

Oh and btw, this is a *massive* testing operation. All students are required to be tested once a week, and faculty and staff are required to be tested once every two weeks. No exceptions. Regardless of vaccination status, regardless of having no symptoms etc. Everyone connected to the university has to be up to date on their covid testing in order to be cleared to be physically on campus.

If your "testing clearance" expires, you lose access to all campus buildings (which have card readers at ever door, you have to use your campus ID with the card reader to get in).

Apparently they did a bunch of modeling over the summer and their models showed that this set up (students once a week, faculty/staff once every two weeks) hit the sweet spot in terms of effectively using tests for preventive measures while not being overly burdensome in terms of time and money.

As an aside, when I go to the test center, I walk in, get my QR code scanned (in the cellphone app), someone scans the sample tube (to connect my code to the code/number on the sample tube), I step outside to spit in the tube. When I'm done, I put the tube in a collect box (when that box is full, it gets taken for processing). Faculty have a separate line from students, so there is *never* any waiting in the faculty line. But even in the student line, I've only ever seen an actual line a few times (like after fall break when they imposed a rule about everyone getting tested twice). The whole testing process takes barely five minutes to complete.

Pique said

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We don't have spit tests here. I would be surprised if they are reliable. Why would anyone get their brain swabbed if they could just spit?

From what I can tell, both from reading and from being here on campus all semester, I think our uni tests are as reliable as any of the other highly reliable tests that are being used.

And I agree, the brain swab is horrible. I can remember early on (once our uni start the spit test) talking to someone at another university and being super surprised that they didn't have access to a spit test. I cannot imagine having to do the nasal swab every week. OMG.

In any case, as I compare and read around, I think our uni is actually doing an amazing job. Way way better than I think I was giving credit for.

Oh, the other thing they're doing is a partnership with the city where they analyze wastewater/sewage every week to see what neighborhoods have a high rate of infection (viral load) in waste water. The city releases that data every week.

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I never said the short turnaround is what makes the rapid tests unreliable.

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We also have the wastewater tested here. It indicates that viral load is far higher than test results would suggest.

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Originally posted by piqué:
Sk, it sounds like your university is doing an amazing job. So relieved for you.

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No question the level of risk is community specific. I think the wastewater tests are a more reliable indicator than the covid tests, so sounds like your whole community is doing an excellent job.

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Originally posted by piqué:

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Originally posted by Cindysphinx:
Interesting.

When I had COVID, the heal department called me. It sounded like a scam, so I didn’t engage. I mean you call, claim you’re with the health department and ask for my date of birth?

If someone balked when I asked them to confirm DOB I would just read it to them. It's just like at the dr's office they want to make sure they've got the right Cindy. HIPPA compliance.

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I figured I already had been told to isolate, and I had reached out to my tennis partner, who was the only person I had been around unmasked.

You know, that ain't good enough, Cindy. When the health department calls they give you very specific information and instructions. None of the positive cases we call already know what to do and not do. All are surprised by the instructions and information. All of them, after saying they were only in contact with certain people, turns out when we go through it day by day, starting 48 hours before their first symptom, with their memory jogged,there were lots more people, once they understand what is meant by close contact and the necessary time frame.

When a positive case doesn't give us the names of those people and their contact info, those are people out walking around in the community spreading covid like typhoid Mary because we didn't have an opportunity to issue a quarantine and provide them with critical information.

Plus there is a ton of info we need for the CDC so they can get a better handle on what is happening, where, when, and to whom. Information that is critical to keeping people safe.