Am I the only one who is still confused by what they're finding in these antibody tests? Are they looking for antibodies that attach to specific features unique to SARS-CoV-2? Because I'm pretty sure even HCoV-NL63 enter lung cells through ACE2 as well. How can they tell antibodies for these viruses apart? Also aren't antibodies effectively developed in a sort of random process?
> Are they looking for antibodies that attach to specific features unique to SARS-CoV-2?
They're all slightly different, but yes they're looking for antibodies against specific parts of SARS-CoV-2, like the N protein [0][1]. I think the N protein ones are most common. I just did a BLASTp against SARS-CoV's N protein and there's maybe ~90% homology? So I would hope they're using a site that's different between the two. Or, there's an assumption that most people have not been previously exposed to SARS-CoV or others with similar N proteins.
> Also aren't antibodies effectively developed in a sort of random process?
Yeah, but there's only so many prominent features to a virus that you can make antibodies against.
I am also curious about this. As I understand it, an immune individual could have any mathematical subset of antibodies from the base set, which is the collection of all proteins that can bind to something on the surface of a COVID-19 virion. Furthermore, I would think these base sets can change slightly for different mutations of the virus.
Perhaps humans tend to have enough random antibody generation that they are likely to start mass producing most of the protein shapes that are able to bind to the virus? And as another commenter pointed out, there are not that many options to bind to.
Look up VDJ recombination[0] for a sense of how antibodies are generated. Ling story short, yeah its pretty random in a really clever process that generates enormous variability. There are also only so many features to bind on the covid virus protein, which are what we test, but there are a lot of antibodies that our body can make against them
you're not wrong to be. I think the problem is that there's this perception that you must be authoritative to get people to do things, and also this perception that science is authoritative. As a former scientist I think both are wrong, and especially science under duress is likely to be even wronger, for many reasons. We don't live in star trek where you can boop boop a console and magically get answers.
I wish we had leaders that had the chutzpah to say things like, "look the science is inconclusive, so we won't arrest you, but please do the right thing and wear masks". But we don't. And also we have people spouting completely non-evidence based assertions like "if you don't force people to wear masks, then they won't". Which of course fuels assholes to flaunt not wearing masks, because now it's not about doing the right thing, it's about freedom.
If you're confused by this, you may need to check your news sources. Experts have been explaining all of this for months. First, people need to stay locked in and keep distance in order to slow down the spreading so health care systems don't get overwhelmed. Second, the disease itself can only be stopped once herd immunity is reached. Ideally, herd immunity is achieved by vaccination, once there is one. Until then, social distancing is needed to limit the number of deaths and keep the health system working. Third, it is not yet clear whether long-lasting immunity can be achieved at all. It's very likely, but there is not yet enough data. Immunity may last from 2 months to 2 years or longer. We don't know yet for sure.
Not sure why you're being downvoted, this is well established. Even with everyone indoors, the US new infection rate remains around 40,000 new cases per day recorded -- and holding steady. Now with states re-opening that can only go one direction, until herd immunity is established.
Those are positive tests. They are remaining high because the number of tests has been increasing. The important metric to track is percent positive tests, which has been consistently dropping for weeks.
I'm curious if that's true -- based on that excellent data, it appears that the number of people who test positive has been pretty much steady. Chances are those were always, and remain, positive tests at the point of care/admission to a hospital. The new tests are likely randos. So long as we continue to see the same raw absolute number of positive tests, I'd say it's not a win -- yet. There's been in fact a steady increase since 4/21 in positive tests in real number terms.
And that's assuming that herd immunity will be established, which we have no way of knowing until we know how long - and if - a person is immune after recovery.
The 40,000 new cases per day is predominantly a function of the number of tests being run. The number of actual infections has far outpaced the number of tests. Look at test positivity rate across NYC for example.
If instead we had done random sampling we could have been very accurately projecting the number of active cases pretty easily, but apparently we’ve mostly decided not to do that until now with the antibody studies.
