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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. Yessica

    Yessica Senior Member (Voting Rights)

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  2. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    There are worrying trends of a "third wave" (or is that fourth) in the UK, with cases per day per million almost ten times higher in the UK compared to the USA on Tuesday. The US death rate is still three times higher (per million), but cases have more than doubled so those rates may well be similar in 2-3 weeks.

    https://www.worldometers.info/coronavirus/country/uk/
    https://www.worldometers.info/coronavirus/country/us/

    Meanwhile in Australia we're freaking out about a handful of local transmission cases per day.
     
    FMMM1, Amw66, Binkie4 and 5 others like this.
  3. Sean

    Sean Moderator Staff Member

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    In fairness, it is because we don't want it to turn into the UK and USA, which it easily could seeing as our outbreak is the Delta variant.
     
  4. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    So what? All SARS-2 is highly infectious. I think naming these variants is often used to deflect blame from authorities...
     
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  5. ahimsa

    ahimsa Senior Member (Voting Rights)

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    Thanks for your link, @Snow Leopard ! I did notice the line that @Yessica quoted - "Most of the vaccinated index patients in our data set (93%) had received only the first dose of vaccine."

    Looking at my question again
    I think that this question is too broad.

    There may be different answers about post-vaccination transmission (by fully vaccinated people, eg, 2 weeks past the final shot) for each of the different brands of vaccine.

    There are different reported effectiveness rates for different vaccines. So it makes sense that there might also be differences when it comes to a fully vaccinated person who gets a breakthrough infection being able to transmit that infection to someone else.

    And even when talking about effectiveness for a single brand of vaccine I've seen different rates of breakthrough infections for different strains of the virus.

    I can't find the quote right now but it was something like for Pfizer it's 95% effective against one strain of the coronavirus but 88% effective against the delta strain. NOTE - these are made up numbers! And I also can't remember whether it was about Moderna or Pfizer. I just remember that the effectiveness was lower for the delta strain.

    Anyway, the point is that the same vaccine can have different rates of effectiveness for different strains. So I think that's one scientific reason why different strains matter? (but this is all way beyond me so maybe I've missed something)

    I know this post is a bit rambling, but I hope it makes sense!

    I'll end by quoting from a study looking into coronavirus transmission after being fully vaccinated (there's probably more than one, this is just the study that I found) -

    This is one of the "we still don't know" quotes that I mentioned in my earlier post.

    But maybe it's only "we still don't know" when it comes to certain brands of vaccine? Maybe it's "yes, we know that it can be transmitted by fully vaccinated people" when it comes to certain vaccines?
     
  6. Wits_End

    Wits_End Senior Member (Voting Rights)

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    I think the vaccine (probably AstraZeneca, since that's what most of us had in the UK at that stage) was shown to greatly reduce transmission, but I couldn't quote you chapter and verse on that one.
     
    Michelle likes this.
  7. Sean

    Sean Moderator Staff Member

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    According to Wikipedia the Delta variant seems to be around 50-60% more transmissible than the Alpha variant. Which is not good.

    However, it also seems to be less fatal, and a double dose of either Pfizer or AZ vaccines are over 90% effective at preventing hospitalisation.
     
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  8. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    That was the (currently most recent) Public Health England data.
    https://www.medrxiv.org/content/10.1101/2021.05.22.21257658v1

    In prior research, efficacy against symptomatic infection has correlated reasonably well with transmission rates, hence I am willing to bet that the vaccines that have higher efficacy against symptomatic (and asymptomatic) infection also have reduced risk of transmission.

    Vaccines have never reduced transmission risk to zero.

    Neither claims are backed by high quality evidence, because behaviour and demographics are not controlled.

    The claims of lower fatalities are strongly biased by the fact that countries have been selectively vaccinating the older/most vulnerable populations.
     
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  9. Mithriel

    Mithriel Senior Member (Voting Rights)

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    In Scotland, the numbers have soared to higher than they have ever been since the pandemic started but hospitalization is still low. It is nothing like it was last year. The proportion of hospital cases needing ICU and the number of deaths deaths are also down.

    Two thirds of the cases are in men under 40 so distribution of the cases is different from before.

    These figures mean that vaccination has been very successful especially in the older population. The numbers have dropped, but are not zero of course.
     
  10. Trish

    Trish Moderator Staff Member

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    I have heard it suggested that the recent surge of cases among young men is largely due to a recent football match.
     
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  11. Mithriel

    Mithriel Senior Member (Voting Rights)

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    "The fitba' it has robbed them o' the wee bit sense they had"
     
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  12. FMMM1

    FMMM1 Senior Member (Voting Rights)

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    Yea and (to me) ludicrously there are comments here (UK) about not wanting to be like Australia!
     
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  13. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Life here has been mostly normal, besides mandatory check-ins at retail premises.
    Many people in Australia are yearning for the time before (ASAP) and seem to mistakenly think that is the situation in the UK.
     
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  14. Wits_End

    Wits_End Senior Member (Voting Rights)

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    Considering that the UK Government is threatening England with the removal of most restrictions in a couple of weeks, I should think they'd want to avoid that situation at all costs. I don't think the results will be pretty.
     
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  15. Snow Leopard

    Snow Leopard Senior Member (Voting Rights)

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    Here is a study in India that found that vaccinated people can transmit the virus to other people.
    https://www.researchsquare.com/article/rs-637724/v1
     
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  16. Mij

    Mij Senior Member (Voting Rights)

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    I plan to wear a mask for at least another year after I'm fully vaccinated.
     
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  17. Mithriel

    Mithriel Senior Member (Voting Rights)

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    I plan on wearing a mask because it will stop me touching my mouth with my glasses keeping my eyes safe. It seems it gives a little bit of protection for the wearer too.

    What is worrying for us is that the people making the choice to not wear a mask are not the ones at risk it is everybody in their vicinity.

    I am quite upset at the thought because I have ventured out shopping 4 times since the pandemic when numbers were low and I enjoyed the way I could choose my own meals and things, it was fun.

    But if the shops are stuffed with people not wearing masks I won't be able to take the risk of becoming ill and my ME making me completely bedridden instead of being able to get up for a time every day. I don't go out often but I don't want to have to give it up.

    It will be ironic if people on the tube are allowed to infect everyone with coronavirus but smoking is forbidden because of the problems for other people.

    (People who can't wear a mask are presumably taking precautions but someone who decides to risk people's health anyway seems to me more likely to be the same person who doesn't think covid would be a problem for them so they are not diligent about hygiene rules.)
     
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  18. Hoopoe

    Hoopoe Senior Member (Voting Rights)

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    I had a discussion with a person who believed that vaccinated people are variant factories because they don't have good antibodies and exert evolutionary pressure on the virus without killing it.

    The idea seems to come from Gøtzsche.

    Is there some truth to this? I read that vaccine-induced antibodies are not neutralizing antibodies (I'm not sure what that means exactly, but it seems to mean the antibodies aren't as good as those that will be produced in a real infection).

    I can't however see why a vaccinated person would be more likely to give rise to dangerous new variants. Surely some protection from non-optimal antibodies is better than none? My mental model of how variants arise is that it's just a matter of random chance resulting in mutations, followed by natural selection of beneficial (for the virus) mutations, so anything that slows or prevents multiplication would be good.

    There also seemed to be the idea that vaccinations interfere with the killing of infected cells.
     
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  19. Barry

    Barry Senior Member (Voting Rights)

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    Speaking without any expertise on this at all.

    Depends how a mutation arises. Are mutations a function of the transference of the virus from one person to another? Or a function of the virus replicating within a person? Either way it would seem that the rate of increase of the virus within a population must inevitably influence the chance of random mutations appearing.
     
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  20. Keela Too

    Keela Too Senior Member (Voting Rights)

    I would imagine the selection pressure of having vaccinated people in the population, would simply be that should a variant arise that our vaccine-generated-immunity can’t tackle, then that variant will spread faster than variants to which we are immune.

    So if covid becomes endemic (highly likely) the we are likely no need regular vaccine boosters against emerging variants.

    Overall though I would think vaccination is likely to suppress the number of new variants that are able to spread rapidly.
     
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