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Approved Covid-19 test potential game changer.

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Approved Covid-19 test potential game changer.

Old 17th Aug 2020, 10:54
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Approved Covid-19 test potential game changer.

Maybe more appropriate for Medical and Health forum, but due to its potential significance I posted it here.

A short term breakthrough in approved Covid 19 testing has just occurred in the USA. It is an open source test called “Saliva Direct” and is approved by the FDA. It is less invasive, produces results in about three hours, with accuracy rates similar to current tests. Importantly according to Forbes the test costs less than $5. It was developed by the Yale School of Public Health with money supplied by the National Basketball Association, and its player association.

I would hope the Saliva Direct test can replace the current tests being performed at airports, where the timeline is days instead of hours. Of course there would be logistical challenges to separate the tested from the non-tested, but lots of people looking for work (among them aircrew) and plenty of space at these facilities at the moment. With this test you could make the airports proper low risk Covid 19 points of entry and exit. Until people are vaccinated this could help reduce the fear of air travel and gaining access to the countries of the world. This at a cost that is insignificant to the damage we are incurring daily. It certainly won’t make flying any more convenient in the near future. But it would beat anything I have seen flying these last six months.

Of course this is potentially not only significant for aviation. Given the costs and time gain you can test a lot more people in a time frame that could help manage any second/third wave.
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Old 17th Aug 2020, 10:59
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Well the current tests are highly inaccurate so god help us if they can do it in a few hours. They test for corona not even covid-19, you can test positive if you had a cold months ago.

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Old 17th Aug 2020, 11:20
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Fine a test telling you don't have it and neither does everyone else at the airrport or aircraft. Then when you get where you are going and catch it. The test for the return leg / flight shows you are positive and are not allowed back, and if aircrew the whole flight is grounded....
Until there is a workable and sufficient vacine......
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Old 17th Aug 2020, 11:45
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Quick, cheap, easy to administer and sufficiently reliable tests could be an opportunity to open up a bit more. However, what needs to come before them is a shift in thinking about the problem. Unfortunately, for now most countries prefer to simply keep their citizens away from all but the safest countries and keep citizens from all but the safest countries away from their own one. This largely explains why many countries are in no rush to review their blanket quarantine policies in favour of ones based on testing. They perfectly understand that replacing the quarantine with a test or even two tests will increase mobility - but that's simply not the goal. Quite the opposite, in fact. Which may be adequate only if the situation is considered to be a short-term one. For the long-term run, it's simply not sustainable.

For how long will this go on is yet to be found out. In the next couple of months we'll definitely see many more waves of tightening and relaxation of travel restrictions here and there. If there's a tested, safe and reliable vaccine in the coming months and mass distribution starts sometime in the first half of 2021, I see it as the immunity certificate replacing all other entry requirements. If not though, some other way round it will probably be looked into as you cannot keep the economy in hibernation mode forever.
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Old 17th Aug 2020, 13:10
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There is of course the wild assumption there will actually be a vaccine. The dreaded WHO are definitely suggesting it is an IF not a WHEN for a vaccine. There is no vaccine for other Corona Viruses (eg the common cold) which mutates all the time.
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Old 17th Aug 2020, 13:27
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These tests are specific for SARS-Cov-2 but I agree there is a high false negative proportion. Their usefulness is in reducing the quarantine time. So 1 negative test and 9 days quarantine is as good as 14 days quarantine. Two PCR tests and you can reduce it to about 5 days

However quarantine, checking temperature and symptoms, and PCR tests merely pick up a proportion of infectious passengers. So if people are coming from areas with very high levels of infection they still are not adequate

The antibody test however is very cheap and has high specificity, and if you are positive you are not infectious - we havent seen a single case of a patient being infected twice - each and every such claim has been discredited. Although the antibodies only last 78 days we know it is normal for antibodies to disappear with time but immunity to continue, but in some hospitals we just bypass that concern by retesting

So the sensible thing to do would be to give an antibody passport for the 13% of people who are safe, and then do 2 antigen tests and 5 days isolation for the others

A vaccine is coming. This is a simple piece of RNA that has only mutated once and the P1 and P2 studies in many different vaccine trials have shown they can produce good antibodies and good T lymphocytes. I wouldnt put my money on any particular vaccine but I would put money on one or more working.
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Old 17th Aug 2020, 16:03
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Originally Posted by DooblerChina View Post
They test for corona not even covid-19, you can test positive if you had a cold months ago.
I think you have a fundamental misunderstanding somewhere along the line here.
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Old 17th Aug 2020, 22:31
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A family member has, because of work requirements & a persistent cough, been tested (negative) 7 or 8 times. Each time they’ve had to isolate between the test & receiving results (2-3 days).

A shorter turn-around would simplify their life, & be less disruptive to their family & their employer.

Faster turnaround may be another small step in society learning to live with COVID-19
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Old 18th Aug 2020, 07:22
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I'm not even remotely medically or scientifically trained but isn't it a true that a virus which is highly infectious generally mutates very slowly (an advantage when producing vaccines)?

I agree we need a multi pronged approach.
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Old 18th Aug 2020, 13:40
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I’m not a virologist, so hopefully one comes by to correct me if I’m wrong, but I don’t see any reason infectivity and mutation rate would be linked. Now if there’s a mutation that changes one of the proteins involved in binding to the host cell, that’s different. But in general, those two things are unrelated.
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Old 19th Aug 2020, 08:14
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CheckAirma : Doobler probably not missing anything. My info is that current test kits identify changes in immune system gene make-up and do not test for the" presence "of the virus at all. Of course, "my info" could be wrong too. Any posts that allude to alternative theories are quickly taken down though. Think about it people. Timing this one..
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Old 19th Aug 2020, 08:35
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AFAIK Some tests look for traces of the virus, others for signs of immunity to it.

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Old 19th Aug 2020, 15:40
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There are many different types of tests, none of them, to my knowledge, test for presence of "the virus" as in whole, viable, infectious virus - that doesn't mean the tests are bad or wrong or that they detect common cold or that they "do not test for the presence of the virus at all".

RT-PCR, the most commonly used (I think) test and certainly the earliest available, tests for the RNA of the virus, identifying specific sections of viral RNA, unique to the virus. Some of the genetic markers used can trigger in lab conditions on the original SARS, none on common cold (see e.g. https://www.fda.gov/media/136151/download performance evaluation section 2, analytical specificity). In real-world, no test is 100% but the PCR is >95% (usually much greater), so if you get a positive test there is a much less than 5% chance it's false.

RT-PCR on the other hand does have a high false-negative rate, up to 30% in some studies. Significant part of this is down to the sample process, which isn't exactly easy or comfortable or exactly repeatable. So if you get a negative test, there is still a chance you have it, and if you have symptoms or significant risk recent contact, that chance may be quite high. In addition to that problem, PCR will only go positive several days after infection, -ve today can still be +ve tomorrow. This is why testing travellers on arrival is pretty pointless and no substitute for quarantine.

Where there is frequent confusion on PCR is that it can show positive on fragments of covid virus, left over debris from your body destroying it. So with a positive test you may not still be shedding viable virus, hence you may not be infectious - but still you almost definitely had it.

Antibody and antigen tests that do do something almost not quite like "identify changes in immune system gene make-up" are a different thing altogether. These tests won't trigger for some weeks after you were infected and unless you are very ill in hospital you will almost certainly not be infectious by then. They are only really useful for seeing how many people in a population have had it. Also although >95% of infected people do make detectable antibodies, they aren't lasting long, tailing off significantly after 3 months or so. No one knows how long immunity lasts, there are T-cells as well, which last longer, and T-cell tests, but no one knows how much immunity these confer or if they reduce disease severity or actually prevent you catching it again and being a carrier/spreader. Which is why "antibody passports" are also pretty pointless and no substitute for quarantine.
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Old 19th Aug 2020, 15:45
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You’re saying that there’s a test that looks to see if the B cells have previously encountered the virus? That’d be interesting for sure. I couldn’t find any information on that, unfortunately. Do you have a link I can read?
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Old 20th Aug 2020, 08:29
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Infrequentflyer789 : Thanks. Gets a bit deep for me and just passing on what I have heard. Check Airman; sorry no. I pass on pub talk & believe in alternative theories. Aaaaaah, damn, probably will go missing now. Mods : thanks . Was worried. VERY worried.
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Old 20th Aug 2020, 11:23
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For those that think we can test our way out of this crisis, I offer the following facts. If after reading, you don’t believe me, go google some of the terms and read up on some epidemiology.

Firstly, consider that no test is perfect. No test will correctly diagnose either a negative or a positive in all cases.

Consider a test that has 95% sensitivity and 95% specificity. Some PCR tests (the one where they stick a swab up your nose) m-a-y approach this level of accuracy. Antigen tests are not as accurate. Sensitivity means the percentage of cases a test correctly identifies as positive. Specificity means the percentage of cases a test correctly identifies as negative. In reality these two figures will be different, but for arguments sake I have made them the same.

Where a disease has low prevalence in the population (as with SARS-CoV-2 right now) even with a highly accurate PCR test with the sensitivity and specificity mentioned above, the probability of a positive test (called the positive predictive value) being correct is as low as 50%.

Testing has a place, but it’s not the be all and end all.

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