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The biology of coronavirus COVID-19 - including research and treatments

Discussion in 'Epidemics (including Covid-19, not Long Covid)' started by Trish, Mar 12, 2020.

  1. Sasha

    Sasha Senior Member (Voting Rights)

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    Just heard a UK government guy (didn't catch his name) essentially seeming to say that the government's policy was to move from Covid being pandemic to endemic. Did I get that wrong, or was it as depressing as I thought?

    No consideration of suppression. I don't feel safe even double-vaccinated, with prevalence as high as it is. I've been shielding since the pandemic started and don't see an end to it. If Covid becomes endemic, what would that mean for prevalence, eventually? Will it ever be safe for the clinically vulnerable to go back into society?
     
  2. Sly Saint

    Sly Saint Senior Member (Voting Rights)

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    Last edited by a moderator: Aug 2, 2021
    Louie41, Wits_End, Michelle and 4 others like this.
  3. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Vaccination with BNT162b2 reduces transmission of SARS-CoV-2 to household contacts in Israel
    https://www.medrxiv.org/content/10.1101/2021.07.13.21260393v1

    This is pre-delta, but I don't think delta would be much different.
     
  4. FMMM1

    FMMM1 Senior Member (Voting Rights)

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    If the Indian variant has a reproductive rate of 6, in unvaccinated people, and the vaccine isn't 100% effective at preventing transmission, then it looks like vaccination alone isn't going to eliminate the virus in the UK.
    See some countries are vaccinating people aged 12+, that might help to get reproductive rate down.
     
    Michelle likes this.
  5. JemPD

    JemPD Senior Member (Voting Rights)

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    So my lay interpretation of that is that I am at significantly lower risk of catching it from people who've had double dose pfizer, a) because they're 80% less likely to have it, & b) because they're ????% less likely to infect me.

    So is it possible from those figures (the 41-79% ones) to say approximately how likely i am to catch it from someone i am indoors with in my home (all other things being equal inc good hygeine/ventilation etc)

    For example my carer is with me on some days for 5hours, indoors all the time, coming close to me some of that time (hair washing etc), she is double jabbed with pfizer. I'd love her not to have to wear a mask anymore (i provide N95 masks for her)... what would your interpretation of the likelyhood of my catching it from her if she werent wearing a mask be, based on this study @Snow Leopard ?
     
    FMMM1 and Michelle like this.
  6. Michelle

    Michelle Senior Member (Voting Rights)

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    responding to this post


    Or this by @sTeamTraen which also suggests a few...er, problems with the big Ivermectin study.
     
    Last edited by a moderator: Aug 2, 2021
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  7. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    If your carer is in the house for 5 hours, it is highly likely you would be infected if they started experiencing symptomatic infection. Given the similarity in protection against symptomatic infection compared to transmission, it is clear symptomatic infection mediates most of the effect. We know from prior studies that true asymptomatic infections (not merely presymptomatic) are far less likely to infect others (10% of the risk compared to symptomatic infections) and those infections are typically associated with touching/kissing, sharing food etc.

    An N95 mask isn't going to provide any protection for you at all. N95 masks protect the wearer, which is why they aren't recommended for the general population since the main effect of mask wearing is protecting others from infected mask wearers.
     
    Michelle, Nellie, FMMM1 and 1 other person like this.
  8. Yessica

    Yessica Senior Member (Voting Rights)

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  9. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Only population based contact tracing studies (where close contacts are tested) can provide answers - and they show true asymptomatic spread is rare:

    "Household transmission of SARS-CoV-2 and risk factors for susceptibility and infectivity in Wuhan: a retrospective observational study"
    https://www.thelancet.com/article/S1473-3099(20)30981-6/fulltext

    There were only 27 secondary cases transmitted from asymptomatic people, out of a total of 8447 secondary cases and 24985 primary cases.

    But of course the above study covered the ancestral strain, rather than the current delta variant.
     
    Mithriel, Michelle, oldtimer and 2 others like this.
  10. Yessica

    Yessica Senior Member (Voting Rights)

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    Thanks @Snow Leopard. :) I'm too foggy to read, at this time, my link or yours well and to ask the right questions of them. Will check both of them out more later. Just sharing the link incase there is anything there that is good and is helpful (what I pursued looked interesting).
     
    Last edited: Jul 24, 2021
    Binkie4 likes this.
  11. JemPD

    JemPD Senior Member (Voting Rights)

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    Thanks very much for that @Snow Leopard
    She wouldn't be here if she was symptomatic so it's only really asymptomatic/presymptomatic that is a concern. She does touch me - helping me in the bath & preparing food for me, but is always scrupulous about hand washing first, so it sounds like the main concern would be a presymptomatic situation.

    I'm astonished to hear you say that N95 will only protect the wearer. I was under the impression that the reason they're not recommended for the general population was an issue of supply & expense, as much as anything else. But whatever the reason they're not generally recommended to everyone, it seems very odd that they would "provide no protection for me at all"... ? That seems very odd. Are you saying the filter doesnt work both ways? (I'm talking about non-vented N95 masks - perhaps you mean the ones with a valve which lets the wearer's breath out.)

    This study seems to say that an N95 is protective for others?
    Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities | Scientific Reports (nature.com)

    From the abstract
    from the detail
    I was surprised to see that a surgical masks protects others to the same or even better degree than the N95 though, but i suppose that would depend on the fit.

    A bit weird that t-shirt masks appeared to increase emissions!
     
    Yessica, oldtimer and Trish like this.
  12. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Yes, I was mostly referring to the ones with the valve. The ones without valves don't seal as well and so they leak around the edges due to the pressure when exhaling. (the purpose of the one-way valves on N95 masks is to prevent leakage for the wearer). They aren't fool proof either, though they are still better than the typical cloth/surgeon masks that people wear (that don't seal up well).
     
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  13. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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  14. JemPD

    JemPD Senior Member (Voting Rights)

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    Ah i see. Thanks for that @Snow Leopard
     
    Yessica likes this.
  15. Sly Saint

    Sly Saint Senior Member (Voting Rights)

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    Huge study supporting ivermectin as Covid treatment withdrawn over ethical concerns
    https://www.theguardian.com/science...vid-treatment-withdrawn-over-ethical-concerns
     
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  16. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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  17. Mij

    Mij Senior Member (Voting Rights)

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    We shouldn't relax when we achieve low levels of cases until we eliminate. Instead, push hard into the finish line. "Living with the virus" is not the right choice. The virus will mutate and we will again have exponential growth.
     
  18. Mithriel

    Mithriel Senior Member (Voting Rights)

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    I was alarmed to see a report that said we are approaching herd immunity, then it turned out it was from an economic think tank.

    It is frightening the way people are pushing for things to get back to normal when what they are pushing is taking us further away all the time.
     
  19. mango

    mango Senior Member (Voting Rights)

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  20. JemPD

    JemPD Senior Member (Voting Rights)

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    I missed that post @mango with the CDC link in, thanks for sharing it most helpful. Would love to see if any updated data as you asked.
     
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