# What are the antibody tests showing now as of late june **URL:** \ **Category:** The Quarantine Zone\ **Tags:** covid-quarantine\ **Created:** [June 25, 2020, 4:52pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013 "2020-06-25T16:52:25Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [June 25, 2020, 4:52pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/1 "2020-06-25T16:52:25Z")
I haven’t been following the news on coronavirus lately. What % of people have been infected based on antibody tests though as of late june? A little over a month ago I think it was around 5-15% of people tested positive for antibodies, higher in places like NYC which was closer to 30%. Anyone know what we’re at now? At this rate it seems the disease will just hit everyone eventually until there aren’t enough new people to infect to keep the R0 above 1. I think masks don’t work unless 50-70%+ of people wear them, and its not at 70% from what I’ve seen. ---
**Author:** ![FinsToTheLeft](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/finstotheleft/32/2930_2.png) [@FinsToTheLeft](https://boards.straightdope.com/u/FinsToTheLeft)\ **Post date:** [June 25, 2020, 6:13pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/2 "2020-06-25T18:13:35Z")
> [@Wesley\_Clark](#): > > Anyone know what we’re at now? At this rate it seems the disease will just hit everyone eventually until there aren’t enough new people to infect to keep the R0 above 1. I think masks don’t work unless 50-70%+ of people wear them, and its not at 70% from what I’ve seen. There seems to be some concern that the immunity is not long lasting and someone who has been infected but was asymptomatic could lose their antibodies within a few months. That would kill herd immunity unless repeated boosters of a future vaccine can keep the immune system ahead of the virus. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [June 25, 2020, 8:57pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/3 "2020-06-25T20:57:36Z")
Well shit, this is the first I’m hearing of this. I thought a study out of south korea found that repeat infections didn’t happen and it was false positives. If so thats going to put a huge wrench in our recovery. ---
**Author:** ![Jackknifed\_Juggernaut](https://avatars.discourse-cdn.com/v4/letter/j/9de053/32.png) [@Jackknifed\_Juggernaut](https://boards.straightdope.com/u/Jackknifed_Juggernaut)\ **Post date:** [June 25, 2020, 9:51pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/4 "2020-06-25T21:51:03Z")
Are there stats on the severity of the disease the 2nd time someone catches it? If it is less severe, it’s not necessarily better for society in general. But would be good to know. ---
**Author:** ![Leaper](https://avatars.discourse-cdn.com/v4/letter/l/4bbf92/32.png) [@Leaper](https://boards.straightdope.com/u/Leaper)\ **Post date:** [June 25, 2020, 9:53pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/5 "2020-06-25T21:53:00Z")
It depends how old the news being referred to is, because I definitely heard this even before the SK study. ---
**Author:** ![Fretful\_Porpentine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fretful_porpentine/32/2873_2.png) [@Fretful\_Porpentine](https://boards.straightdope.com/u/Fretful_Porpentine)\ **Post date:** [June 25, 2020, 10:32pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/6 "2020-06-25T22:32:37Z")
I don’t quite know what to believe (possibly because nobody knows for sure?) but [this NYT article](https://www.nytimes.com/2020/06/18/health/coronavirus-antibodies.html) quotes a couple of credible-sounding experts who say that immunity can persist despite a drop in antibody levels, as well as one who sounds more pessimistic. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [June 26, 2020, 2:37am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/7 "2020-06-26T02:37:30Z")
A different article, one that omits anything about memory B cells, I read earlier this week mentioned that they think some people are primarily fighting the infection off with T cells rather than antibodies. ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [June 26, 2020, 2:44am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/8 "2020-06-26T02:44:49Z")
There’s a nice paper (preprint) on seroprevalence studies worldwide [here](https://www.medrxiv.org/content/10.1101/2020.05.13.20101253v2.full.pdf+html) . (Folks may or may not recognise the author - John Ionannidis - as a medium famous name in Replication Crisis research … in any case, very reputable. The paper is actually about trying to estimate fatality rates, but in the service of that they combed the literature for as many good seroprevalence studies as they could find. Mostly pre-May, sadly, iow a bit out of date now, but they quote an estimate from a Brooklyn study, early May, of 47% 😮 . That’s an incredible hot spot, however. Studies based on testing in May is probably about as good as we’re likely to get right now in the ‘peer reviewed research’ stakes. There may be some more recent data available as just a press release, but I haven’t heard of anything myself. ---
**Author:** ![barkodogo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/barkodogo/32/3911_2.png) [@barkodogo](https://boards.straightdope.com/u/barkodogo)\ **Post date:** [June 26, 2020, 2:53am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/9 "2020-06-26T02:53:11Z")
> [@Wesley\_Clark](#): > > At this rate it seems the disease will just hit everyone eventually until there aren’t enough new people to infect to keep the R0 above 1 We’re still a long way off from herd immunity. You need to get a majority of the population immune (some experts say 60% at least). > **[The World Is Still Far From Herd Immunity for Coronavirus (Published 2020)](https://www.nytimes.com/interactive/2020/05/28/upshot/coronavirus-herd-immunity.html)** > > The latest studies show that even in the hardest-hit cities, most people remain vulnerable. This is from mid may, but NYC was only at 20% and the infection rate has only dropped (in NYC) since. So _maybe_ one of the worst hit places in the country is halfway there? If the whole country averaged out to 10% w/ antibodies today and the death rate remained consistent we’d be looking at easily a half a million more deaths before hitting the right numbers for herd immunity. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [June 26, 2020, 4:25pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/10 "2020-06-26T16:25:32Z")
As has often been the case there are problems with even recognizing what is still completely unknown, and lots of reporting that only gives small parts of the complete pictures. First unknown - to what degree does infection with SARS-CoV-2 confer protection and for how long? Related question being how good is any specific level of specific antibodies as a proxy of that protection or of past infection, especially of milder cases? Widely agreed best guess extrapolating from other HCoVs is likely quite good levels of protection (but not 100%) for likely 2 to 3 years. But could be less or more. If less then the expectation would be that a next infection would minimally be less severe and likely less contagious. _Known_ that antibody levels are NOT in general a perfect proxy of protection. High levels are a pretty good proxy of having it, but low levels NOT a good proxy for not, both because of the roles of specific and long lasting T cells, and because of the potential impact of _non-specific_ HCoV antibodies. Unknown if ANYONE has yet had a true re-infection. Would be truly surprising if the number was zero but the [evidence to date](https://www.physiciansweekly.com/risk-for-covid-19-reinfection-remains-unknown/) is very sketchy. Next unknown: what percent of the population need to be functionally non-susceptible for herd immunity or at least for spread to slow down? Often quoted is the common guess, based on experience with influenzas, of maybe 60%. That said we have learned that this virus in many ways has not behaved as an influenza virus would. There should be no great confidence that that number is correct. Could it be significantly higher? Yes. Could it be significantly lower? Yes. _Again_ there is the _unknown_ degree to which recent and/or frequent past infections with common cold causing HCoVs provide levels of protection and/or decreased transmissibility by way of non-specific antibodies followed by specific T-cell responses. There is the emerging more and more as strong probability that a large segment of the population, children, especially younger children who for influenza are major amplifiers of spread, rarely transmit the infection when they do catch it. IF proven to be true, then there is some significant share of the population, mostly among children, who would function as non-susceptibles in modeling. But unknown. Known from samples collected long before the pandemic and recently tested that 30% of adults have T-cells that respond to SARS-CoV-2 without ever having been exposed to it. Known to pretty high degree of confidence: long before true herd immunity a smaller pool of susceptibles will result in a flatter curve during a next wave. Known: herd immunity is not a physical constant but is a number that will be different based on specifics of a specific culture, demographics, and behaviors. Known - seroprevalence numbers reflect infection rates two to three weeks before they were measured, and then usually about two weeks more before they were reported. Reporting that states a current report as reflect the reality of today is confused. Known - until global herd immunity is achieved herd immunity is more local than politics. Average across the country matters less than what is in a specific region. FWIW. Apply to interpretation as you will. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [July 8, 2020, 3:32am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/11 "2020-07-08T03:32:41Z")
This is probably a dumb question, but it’s not worthy of its own GQ thread… how do the antibody tests for Covid-19 work? Are they able to just exam a blood sample to see if they’re present/not present, or are they doing something _to_ the sample - presumably introducing the virus to the sample - to see if it evokes a response? Movies about pandemics seem to do the latter as they peer into closeups of microscope slides, but is blood outside our bodies for as long as blood samples are before processing still reactive to anything? ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [July 8, 2020, 3:34am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/12 "2020-07-08T03:34:27Z")
This photo is pretty informative about the types of tests. [![](https://www.lungevity.org/sites/default/files/COVID-19/types-of-coronavirus-testing-web.png) ](https://www.lungevity.org/sites/default/files/COVID-19/types-of-coronavirus-testing-web.png) ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [July 8, 2020, 3:41am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/13 "2020-07-08T03:41:51Z")
I read it, but I still don’t understand what is being done to detect the antibody. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [July 8, 2020, 4:34am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/14 "2020-07-08T04:34:42Z")
The basic idea is that they create a protein like one of the virus and specific to the virus. Antibody attaches to it and they measure how much by various methods. ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [July 8, 2020, 7:52am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/15 "2020-07-08T07:52:49Z")
> [@Aspidistra](#): > > There’s a nice paper (preprint) on seroprevalence studies worldwide [here](https://www.medrxiv.org/content/10.1101/2020.05.13.20101253v2.full.pdf+html) . (Folks may or may not recognise the author - John Ionannidis - as a medium famous name in Replication Crisis research … in any case, very reputable. He WAS reputable. He actually is most famous for telling several scientific fields [how shoddy their work is and why it shouldn’t be trusted](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1182327/). [Unfortunately](https://statmodeling.stat.columbia.edu/2020/04/19/fatal-flaws-in-stanford-study-of-coronavirus-prevalence/), [he’s](https://www.the-scientist.com/news-opinion/how-not-to-do-an-antibody-survey-for-sars-cov-2-67488) [currently](https://thehealthcareblog.com/blog/2020/04/24/is-the-covid-19-antibody-seroprevalence-in-santa-clara-county-really-50-85-fold-higher-than-the-number-of-confirmed-cases/) [more](https://twitter.com/natesilver538/status/1252973441193558017) [famous](https://twitter.com/JeanClaudeFox2/status/1251894101873737729) [for](https://www.nationalgeographic.com/science/2020/05/why-unreliable-tests-are-flooding-the-coronavirus-conversation-cvd/) [horrendously](https://www.salon.com/2020/04/26/scientists-feud-over-hyped-stanford-coronavirus-antibody-study-the-authors-owe-us-all-an-apology/) [sloppy](https://www.businessinsider.com/buzzfeed-stanford-coronavirus-study-funded-by-jetblue-founder-2020-5) [research](https://www.dailydemocrat.com/2020/05/24/did-politically-motivated-scientists-hype-their-speedy-study/). ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [July 8, 2020, 8:01am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/16 "2020-07-08T08:01:48Z")
As for the OP, we really don’t have a good idea yet. The CDC is actually attempting to do some good sampling, i.e. picking random addresses and actually going to the door to perform the test. Unfortunately, that takes a long time and we don’t have significant results yet. Almost every other survey I’ve seen has been so poorly representative that it’s pretty worthless. For example, the Boston test where they randomly tested people who passed by on a particular street corner. The only thing that study is good for is determining the infection rate of people who live, work, exercise, or shop in that area, and chose to walk instead of drive or bike. Attempting to extrapolate that to the infection rate of Boston is ludicrous. It is possible that I have missed some survey that was done well, so feel free to link to them if you have them. ---
**Author:** ![Aspidistra](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aspidistra/32/3894_2.png) [@Aspidistra](https://boards.straightdope.com/u/Aspidistra)\ **Post date:** [July 8, 2020, 9:34am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/17 "2020-07-08T09:34:42Z")
Well, that’s sad. Still, given the number of authors on that study I’ll reserve putting too much judgement on any given participant, but it’s certainly a reminder to judge any piece of work on its merits, rather than on reputation ---
**Author:** ![DMC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dmc/32/18049_2.png) [@DMC](https://boards.straightdope.com/u/DMC)\ **Post date:** [July 8, 2020, 10:24am UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/18 "2020-07-08T10:24:54Z")
Nate Silver put it most succinctly: > “A test that _could_ have a false positive rate of up to ~2-3% isn’t saying very much if it detects 2-3% positives in some population.” ---
**Author:** ![PoppaSan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/poppasan/32/189_2.png) [@PoppaSan](https://boards.straightdope.com/u/PoppaSan)\ **Post date:** [July 9, 2020, 5:45pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/19 "2020-07-09T17:45:57Z")
Kind of wish the blood drive people would sample test their collections. They’ve already done the gathering. They tell me where my donation was used (3yo in Selma with leukemia, 30yo accident in Abilene, 68 yo heart surgery in Bismark, etc) so they know whose is whose. Be a decent cross section of society and locations. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [July 13, 2020, 11:41pm UTC](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013/20 "2020-07-13T23:41:13Z")
I found this interesting: [Immunity to COVID-19 is probably higher than tests have shown](https://news.ki.se/immunity-to-covid-19-is-probably-higher-than-tests-have-show), which is about research done in June at the Karolinska Institutet and Karolinska University Hospital in Sweden. > [@](#): > > “One interesting observation was that it wasn’t just individuals with verified COVID-19 who showed T-cell immunity but also many of their exposed asymptomatic family members,” says Soo Aleman. “Moreover, roughly 30 percent of the blood donors who’d given blood in May 2020 had COVID-19-specific T cells, a figure that’s much higher than previous antibody tests have shown.” But unfortunately “The results are so new that they have not yet undergone peer review ahead of publication in a scientific journal. Pending such review, the article has been published on a preprint server, bioRxiv” so there’s a chance that it might not turn out to be replicable like early research often isn’t. [Next page](https://boards.straightdope.com/t/what-are-the-antibody-tests-showing-now-as-of-late-june/913013.md?page=2)