7 ms·

Is there any evidence you can re-contract Covid-19? If not, I'd fall back to the following argument: Some health care workers have been exposed regularly for si

Is there any evidence you can re-contract Covid-19? If not, I'd fall back to the following argument: Some health care workers have been exposed regularly for six months by now. It'd be very news worthy if someone was confirmed to be re-infected. Given I haven't seen that news, I think I can conclude that immunity lasts at least six months in working age people. Also, if I understand correctly, it has recently been shown that people who were infected with SARS 17 years ago still have memory T cells for SARS. (And, I think SARS is one of the viruses most closely related to Covid-19, and therefore there's reason to expect a long immunity period for it too). "Memory T cells induced by previous pathogens can shape the susceptibility to, and clinical severity of, subsequent infections. <snip> We then showed that SARS-recovered patients (n=23) still possess long-lasting memory T cells reactive to SARS-NP 17 years after the 2003 outbreak." - from https://www.nature.com/articles/s41586-020-2550-z https://www.nature.com/articles/s41586-020-2550-z

claudeganon 6y ago
There’s initial evidence of reinfection and limited immunity that are under further investigation: https://www.vox.com/2020/7/12/21321653/getting-covid-19-twice-reinfection-antibody-herd-immunity https://www.vox.com/2020/7/12/21321653/getting-covid-19-twic... https://www.theguardian.com/world/2020/jul/12/immunity-to-covid-19-could-be-lost-in-months-uk-study-suggests?CMP=share_btn_tw https://www.theguardian.com/world/2020/jul/12/immunity-to-co...
- __blockcipher__ 6y ago
  There is no credible evidence of re-infection. The isolated cases can be explained away in a bayesian sense by PCR false positives or false negatives. It’s the usual base rate neglect fallacy. The idea of reinfection contradicts decades of well established immunological principles. It also ignores the fact that we have a close relative of SARS-2 to study. That relative is SARS-1 and we have detected strong t cell activation after 17+ years. Therefore immunity is enduring and long lasting. SARS-2 is substantially structurally similar to SARS-1. Alternatively, take a statistical argument. There have been millions of cases around the world. SARS-2 is highly infectious for those who are susceptible. Therefore we would have thousands if not more well-documented, inarguable cases of reinfection. We don’t have those. All we have is a bunch of articles from heavily biased sources like Vox that have a vested interest in pushing the “doomer” narrative. Why haven’t we seen widespread reinfection if it is truly possible?
  - claudeganon 6y ago
    As I pointed out downthread, there's a Kings College study under review that says antibodies seems to wane rapidly: https://www.sfchronicle.com/health/article/With-coronavirus-antibodies-fading-fast-focus-15414533.php https://www.sfchronicle.com/health/article/With-coronavirus-... https://www.medrxiv.org/content/10.1101/2020.07.09.20148429v.. https://www.medrxiv.org/content/10.1101/2020.07.09.20148429v.... Likewise, asymptomatic cases appear to have limited immune duration and development: https://www.jci.org/articles/view/138759#ABS https://www.jci.org/articles/view/138759#ABS And meaningful immunity might depend on how much of the virus one is exposed to: https://www.nature.com/articles/s41591-020-0965-6 https://www.nature.com/articles/s41591-020-0965-6 If this research holds up, we'll have your well documented cases in probably 3-6 months. Frontline doctors, outside the one cited in the Vox article, are already insisting its true.
    - __blockcipher__ 6y ago
      Antibodies do wane, and they are supposed to. They generally don't last longer than a few months with SARS-[1,2]. Even though they wane, memory b cells persist, meaning subsequent infection is milder and theoretically less transmissible. Additionally that reinfection potential only exists if you ignore t-cells. When you factor in t-cells, it simply does not happen. We're in July 2020. SARS-2 existed since some point in 2019, probably midway through. Granted we couldn't detect reinfection until the whole globe had been freaking out about it, so let's start our clock from January 2020. It's been 6 months and we don't have dozens of well-documented, credible reinfections? No, such one-off supposed reinfections are much more explainable from a bayesian perspective of either false positives or false negatives of PCR. Find me someone who is not immunocompromised, who is PCR-positive for SARS-2 and from whom viable SARS-2 is successfully cultured, then show them fighting off the infection and being PCR-negative and symptom-free for weeks, then show me them being PCR-positive again with viable SARS-2 cultured from their body. That's the standard. 20 examples of that and reinfection definitely happens. Until then, our priors are that we should assume it does not. Such fears are just used to argue against herd immunity, which has been made into a "dirty word" (phrase). Herd immunity is a natural phenomenom, arguing "against" it is like arguing against natural selection in my book. (The analogy is not perfect but I hope you see the point. I'm tired of being called callous for saying "hey let's not fuck with the normal population immunity dynamics that we've used for every other highly infectious virus in existence") --- BTW, I can't find the study but they have tested reinfection in primates and showed them unable to get reinfected

claudeganon 6y ago

There’s initial evidence of reinfection and limited immunity that are under further investigation: https://www.vox.com/2020/7/12/21321653/getting-covid-19-twice-reinfection-antibody-herd-immunity https://www.vox.com/2020/7/12/21321653/getting-covid-19-twic... https://www.theguardian.com/world/2020/jul/12/immunity-to-covid-19-could-be-lost-in-months-uk-study-suggests?CMP=share_btn_tw https://www.theguardian.com/world/2020/jul/12/immunity-to-co...

__blockcipher__ 6y ago
There is no credible evidence of re-infection. The isolated cases can be explained away in a bayesian sense by PCR false positives or false negatives. It’s the usual base rate neglect fallacy. The idea of reinfection contradicts decades of well established immunological principles. It also ignores the fact that we have a close relative of SARS-2 to study. That relative is SARS-1 and we have detected strong t cell activation after 17+ years. Therefore immunity is enduring and long lasting. SARS-2 is substantially structurally similar to SARS-1. Alternatively, take a statistical argument. There have been millions of cases around the world. SARS-2 is highly infectious for those who are susceptible. Therefore we would have thousands if not more well-documented, inarguable cases of reinfection. We don’t have those. All we have is a bunch of articles from heavily biased sources like Vox that have a vested interest in pushing the “doomer” narrative. Why haven’t we seen widespread reinfection if it is truly possible?
- claudeganon 6y ago
  As I pointed out downthread, there's a Kings College study under review that says antibodies seems to wane rapidly: https://www.sfchronicle.com/health/article/With-coronavirus-antibodies-fading-fast-focus-15414533.php https://www.sfchronicle.com/health/article/With-coronavirus-... https://www.medrxiv.org/content/10.1101/2020.07.09.20148429v.. https://www.medrxiv.org/content/10.1101/2020.07.09.20148429v.... Likewise, asymptomatic cases appear to have limited immune duration and development: https://www.jci.org/articles/view/138759#ABS https://www.jci.org/articles/view/138759#ABS And meaningful immunity might depend on how much of the virus one is exposed to: https://www.nature.com/articles/s41591-020-0965-6 https://www.nature.com/articles/s41591-020-0965-6 If this research holds up, we'll have your well documented cases in probably 3-6 months. Frontline doctors, outside the one cited in the Vox article, are already insisting its true.
  - __blockcipher__ 6y ago
    Antibodies do wane, and they are supposed to. They generally don't last longer than a few months with SARS-[1,2]. Even though they wane, memory b cells persist, meaning subsequent infection is milder and theoretically less transmissible. Additionally that reinfection potential only exists if you ignore t-cells. When you factor in t-cells, it simply does not happen. We're in July 2020. SARS-2 existed since some point in 2019, probably midway through. Granted we couldn't detect reinfection until the whole globe had been freaking out about it, so let's start our clock from January 2020. It's been 6 months and we don't have dozens of well-documented, credible reinfections? No, such one-off supposed reinfections are much more explainable from a bayesian perspective of either false positives or false negatives of PCR. Find me someone who is not immunocompromised, who is PCR-positive for SARS-2 and from whom viable SARS-2 is successfully cultured, then show them fighting off the infection and being PCR-negative and symptom-free for weeks, then show me them being PCR-positive again with viable SARS-2 cultured from their body. That's the standard. 20 examples of that and reinfection definitely happens. Until then, our priors are that we should assume it does not. Such fears are just used to argue against herd immunity, which has been made into a "dirty word" (phrase). Herd immunity is a natural phenomenom, arguing "against" it is like arguing against natural selection in my book. (The analogy is not perfect but I hope you see the point. I'm tired of being called callous for saying "hey let's not fuck with the normal population immunity dynamics that we've used for every other highly infectious virus in existence") --- BTW, I can't find the study but they have tested reinfection in primates and showed them unable to get reinfected