Blackstone

Have you been mis-sold PPI?

Just wanted to make another post about test accuracy. This isn't really directly applicable to coronavirus testing though, for reasons I'll explain. It's not simply enough to know a test's sensitivity and specificity. What is a far more useful figure is the 'positive predictive value' and the 'negative predictive value'. The PPV is the probability that someone who tested positive actually has the disease. Conversely the same for the NPV. The PPV and NPV depends heavily on how prevalent a disease is in a given population. This is easier with a worked example: Let's say we have a test that is 99% sensitive and 99% specific. That is to say, if it is used to test 100 positive people, it will return 99 positive results, and one false negative result. And if it tests 100 negative people, it will return 99 negative results, and one false positive result. On paper, this is a great test. But, let's say that in a population of people, this disease only affects 1 in 1000 of them. If you randomly screened 1000 people with this test, then you would expect 11 of those results to return positive. One of those is the actual true positive case. The other 10 are false positive results. That means that for every true positive, you have 10 false positives. That's a 9% positive predictive value. This is why blindly screening for rare diseases can be a waste of time and money, and can actually be harmful. And this is why you only perform certain tests on high-risk people who do have a high chance of actually having the disease. Now, this isn't applicable to coronavirus because of how widespread COVID-19 is, I just wanted to give an example of why accuracy of tests is actually quite a complex subject.

I don't know much about this theory of two different strains. However, there does seem to be reports that the Spike protein (how the virus attaches to our cells) is undergoing significant mutation. This would be a problem as it means that our immune system will no longer recognise that spike protein. This means the antibodies will no longer be able to bind to them to "deactivate" them. I believe the original SARS virus had a pretty genetically stable spike protein. Coronaviruses in general are much more stable than Influenza viruses. I'm not too worried about this right now, but this could change as more research is done. I would take the reports of re-infections with a grain of salt. In many of these cases, it is likely that "reinfection" was really just the PCR test detecting bits of dead virus. Or the patient had a previous false-negative test, and hadn't actually recovered (I refer back to my earlier post about the "accuracy" of PCR tests).

Their test looks suspiciously like a Chinese test that we've seen, so I don't think they are actually making it...

It sounds like the WHO are being overly cautious because of a lack of peer-reviewed studies. The fact is that there HAS to be some degree of immunity, otherwise you wouldn't be able to recover from the infection. There are two forms of long-term immunity - humoral (antibody-based) and cell-mediated (memory T-cells). The easiest to study is humoral immunity, because it's easier to measure how much antibody someone has. Long-term immunity is provided by Immunoglobulin G (IgG), which is produced about 2 weeks into an infection. IgG levels peak at 4 weeks and then slowly decrease over time. Their presence in blood should provide immunity for at least a year. In the case of the 2003 SARS virus, a followup study found that most people did not have detectable IgG to SARS after 6 years. However, this doesn't mean they aren't immune anymore, because you should still have your cell-mediated immunity. Cell-mediated immunity makes use of memory cells, who can remember the particular pathogen that originally invaded the body. When reinfection occurs, they can immediately reactivate the body's defences against that pathogen (phagocytes, killer T-cells, cytokines etc...). There are also memory B-cells that when activated, will produce IgG antibodies again. Cell-mediated immunity is a little harder to measure, because you have to take someone's blood, introduce bits of the virus to it, and see if there is any response to it. (As an aside, this cell-mediated immunity test is called an Interferon Gamma Release Assay, and is one of the only ways of diagnosing people who have a latent tuberculosis infection. That is, they have TB, but do not show any signs of it, and do not even have antibodies to it) So the reason why WHO is saying that there is no guarantee of immunity, is only because there is little peer-reviewed research into this. Nobody knows how long the initial antibody response is good for. And nobody knows the nature of the cell-mediated immunity to it.

The nucleic acid test (swab test) accuracy depends a lot on the quality of the swab, and where you swab. Best sample type is from a bronchoalveolar lavage (a thoroughly unpleasant procedure where they flush your lungs with fluid and then collect it. you have to be sedated for this procedure, and it's very dangerous to the people carrying out the procedure due to the risk of splashing and aerosols). Most swabs are taken from the nose/throat, and those samples will only give around a 70% accurate result. That's not how it works. You can't really apply "accuracy" to a test. A test's performance is separated into two things: sensitivity and specificity. A test's sensitivity is how good it is at correctly identifying a positive result. A low sensitivity results in more false negatives. A test's specificity is how good it is at correctly identifying a negative result. A low specificity results in more false positives. "Accuracy" is just a measure of how much a test agrees with the results of a "gold standard" test that it's being compared to. But it's really not a useful metric beyond trying to explain the test's effectiveness to a layperson.

The Government have been woefully slow at engaging with industry over these antibody tests. The specifications for the antibody tests themselves are also absurd and unrealistic.

It's partly the mentality that anything Western or foreign must be good...even Leicester

If there is a large vehicle in front of you that is blocking your view of the incoming lane, you don't just blindly pull out to have a gander. Drop your speed and fall back a bit. To think any blame lies with the two deceased motorcyclists is absurd.

Flu is caused by a different family of viruses. The virus at the centre of this outbreak is Coronavirus, which is the same family of viruses that can cause the common cold. But yes, they still don't typically live for longer than 24 hours outside of a host.

Hope love island discussion also gets banned too

So uhh, the Brexit Party leader Nigel Farage is now demanding an extension because he doesn't like this deal.

It's Schrodinger's Brexiteer

Are you suggesting that the will of the Executive is unable to be challenged? That sounds very dangerous. The Prorogation was carried out by an Order in Council at a meeting of the Privy Council. In effect, the Executive goes to the Queen and informs her they want to prorogue Parliament. And Parliament has no say in this matter, it is purely a decision by the Executive. The Executive, Judiciary and Legislature form the system of checks and balances fundamental to the healthy functioning of any democracy as it prevents any one entity from becoming too powerful. The Executive, by proroguing Parliament, prevented the Legislature from exercising its right to scrutinise and hold the Executive to account. Therefore, the Judiciary stepped in and ruled this unlawful under Constitutional law. Many (in this thread) are making bogus claims that the Supreme Court made up a new law, or are interfering with Parliamentary business. For one, the Judiciary cannot make laws, only Parliament can do that. Also, note that they found that the PM acted unlawfully, not illegally. There is a subtle difference between the two. If something is illegal, it is explicitly prohibited by law. If something is unlawful, that just means it is not authorised by law. The charge of interfering with Parliamentary business is not true either, as the process of prorogation was not conducted in Parliament. It was not a motion or a bill that was passed in Parliament. It was solely an action of the Executive and so the Court could rule on it. Another false claim that I've seen in this thread is that the Court ruled on the PM's motive for proroguing Parliament. This is untrue. His motive for doing so was irrelevant to the court, they were only concerned with the effect of the prorogation.

I don't know if people like you and Vince Green are genuinely or intentionally ignorant. The Supreme court did not overrule Parliament. It specifically cannot rule on the actions of Parliament. It ruled on the actions of the Executive. Parliament had no say in the Order of Council that was made to prorogue Parliament.