8 ms·

https://www.nejm.org/doi/full/10.1056/NEJMoa2102214 https://www.nejm.org/doi/full/10.1056/NEJMoa2102214 CONCLUSIONS A two-dose regimen of the ChAdOx1 (AstraZe

https://www.nejm.org/doi/full/10.1056/NEJMoa2102214 https://www.nejm.org/doi/full/10.1056/NEJMoa2102214 CONCLUSIONS A two-dose regimen of the ChAdOx1 (AstraZeneca) nCoV-19 vaccine did not show protection against mild-to-moderate Covid-19 due to the B.1.351 variant. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT04444674. opens in new tab; Pan African Clinical Trials Registry number, PACTR202006922165132. opens in new tab).

zimpenfish 6y ago
I thought the point of the vaccines wasn't to provide an absolute block against the virus but to reduce the incidence of severe symptoms and hospitalisations? Rather than running rampant and killing hundreds of thousands, it'll be pushed down to mild flu or common cold kind of levels?
- Dylan16807 6y ago
  That's definitely not "the" point. Reducing spread is also extremely important.
  - ppf 6y ago
    It most certainly is the point. Many other vaccines also do not provide sterilising immunity.
    - Dylan16807 6y ago
      That makes them a significantly worse vaccine. If you had a vaccine that only prevented spread, not illness, it would still be useful.
      - ppf 6y ago
        Well, it's what we got, and it's how we plan to get out of this (apparently). Also, what's wrong with a vaccine that stops people dying?
        nicoburns 6y ago
        It still allows the virus to replicate and mutate, potentially into a variant that is different enough that the vaccine no longer prevents people from dying.
        ppf 6y ago
        Like I said - so do many vaccines. I suppose we need to all lock ourselves back in our houses for a few more years while researchers make a new vaccine for Covid-19, that does provide sterlising immunity? This is why creating a vaccine for coronaviruses is a fool's errand. This is all very predictable. We have to look at the actual harm being done, and decide if all this is worth it.
        sharken 6y ago
        Indeed, some realism to the coronavirus aftermath has been lacking. If the vaccines do reduce hospitalizations and ultimately deaths, then we can live with it and can forget about vaccine passes and restrictions. Getting your optional and yearly coronavirus booster is a likely and realistic outcome of all this.
        Symmetry 6y ago
        Sure, but your normal immune response applies the same selective pressures and allows order of magnitude more replication prior to that giving the virus orders of magnitude more chances to come up with a mutation to circumvent them. Even without preventing infection entirely vaccination still seems drastically better than the alternative.
        Dylan16807 6y ago
        > it's what we got Citation needed. (And I don't mean citing someone that says "not yet proven") > and it's how we plan to get out of this Are we hearing the same news? There is so much emphasis on stopping spreading. > Also, what's wrong with a vaccine that stops people dying? ...? Nothing. Where did you get the idea I was saying that? Vaccines have two primary goals. If a vaccine only does one it's a huge downgrade but still valuable.
      - Symmetry 6y ago
        Vaccines generally drastically reduce the spread of disease with needing to provide sterilizing immunity. If you just reduce spread by a factor of 20 that's enough to bring R0 down below 1 for almost any disease. It's a numbers game.
        ppf 6y ago
        "just a factor of 20" is a huge number. At this point, it's not even clear if the vaccines stop you becoming infected in the first place, or just reduces your symptoms. In that case, a vaccinated person is no better for transmission than an unvaccinated, "asymptomatic carrier".
        Symmetry 6y ago
        I chose that number because people who are infected but remain asymptomatic through their infection seem to cause 20 times fewer infections according to a couple of contact tracing studies I saw. It seems pretty clear that the amount of fluid you have to get from an infected person, droplet or aerosol, has to be inversely proportional to their viral load if you're to get infected. Current guesses of an infectious dose I've seen are 100 to 1000 virions via the aerosol route. We can see that different people reach peak viral loads that are orders of magnitude apart which helps make sense of why this disease has such a high k, driven by superspreaders whereas half of people fail to infect anyone else even without protective measures.
        ppf 6y ago
        So if I promise to isolate myself if I get symptoms, and am not concerned about Covid, why should I get vaccinated?
        Symmetry 6y ago
        It's the people who remain asymtomatic through their infections who barely infect others. For people who end up becoming symptomatic their viral load and infectiousness peaks somewhere in the day before symptoms first appear. That's the one thing we've found about this virus so far that's genuinely weird. It seems to be very good at evading the automatic immune system but once the Interferon starts flowing the viral population starts crashing immediately.
- samastur 6y ago
  Yes, that's often neglected. However this paper states that the lack of severe reactions may be down to the age of participants (around 30 years) so it is basically unknown if it reduces those.
- kolinko 6y ago
  If the vaccine doesn’t protect from mild symptoms, there is no reason to think it would protect from severe.
  - dbetteridge 6y ago
    I mean if you actually read the published data that is categorically wrong. The variant in question escapes Antibody detection, but T-Cells still seem to provide significant protection against severe disease and death. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab083/6124512 https://academic.oup.com/cid/advance-article/doi/10.1093/cid... https://www.biorxiv.org/content/10.1101/2021.03.11.435000v1 https://www.biorxiv.org/content/10.1101/2021.03.11.435000v1 The main published results aren't yet from human scale studies but here is one in hamsters showing a comparison in organ damage and results between unvaccinated and vaccinated with the Oxford/AZ vaccine.

zimpenfish 6y ago

I thought the point of the vaccines wasn't to provide an absolute block against the virus but to reduce the incidence of severe symptoms and hospitalisations? Rather than running rampant and killing hundreds of thousands, it'll be pushed down to mild flu or common cold kind of levels?

Dylan16807 6y ago
That's definitely not "the" point. Reducing spread is also extremely important.
- ppf 6y ago
  It most certainly is the point. Many other vaccines also do not provide sterilising immunity.
  - Dylan16807 6y ago
    That makes them a significantly worse vaccine. If you had a vaccine that only prevented spread, not illness, it would still be useful.
    - ppf 6y ago
      Well, it's what we got, and it's how we plan to get out of this (apparently). Also, what's wrong with a vaccine that stops people dying?
      - nicoburns 6y ago
        It still allows the virus to replicate and mutate, potentially into a variant that is different enough that the vaccine no longer prevents people from dying.
        ppf 6y ago
        Like I said - so do many vaccines. I suppose we need to all lock ourselves back in our houses for a few more years while researchers make a new vaccine for Covid-19, that does provide sterlising immunity? This is why creating a vaccine for coronaviruses is a fool's errand. This is all very predictable. We have to look at the actual harm being done, and decide if all this is worth it.
        sharken 6y ago
        Indeed, some realism to the coronavirus aftermath has been lacking. If the vaccines do reduce hospitalizations and ultimately deaths, then we can live with it and can forget about vaccine passes and restrictions. Getting your optional and yearly coronavirus booster is a likely and realistic outcome of all this.
        Symmetry 6y ago
        Sure, but your normal immune response applies the same selective pressures and allows order of magnitude more replication prior to that giving the virus orders of magnitude more chances to come up with a mutation to circumvent them. Even without preventing infection entirely vaccination still seems drastically better than the alternative.
      - Dylan16807 6y ago
        > it's what we got Citation needed. (And I don't mean citing someone that says "not yet proven") > and it's how we plan to get out of this Are we hearing the same news? There is so much emphasis on stopping spreading. > Also, what's wrong with a vaccine that stops people dying? ...? Nothing. Where did you get the idea I was saying that? Vaccines have two primary goals. If a vaccine only does one it's a huge downgrade but still valuable.
    - Symmetry 6y ago
      Vaccines generally drastically reduce the spread of disease with needing to provide sterilizing immunity. If you just reduce spread by a factor of 20 that's enough to bring R0 down below 1 for almost any disease. It's a numbers game.
      - ppf 6y ago
        "just a factor of 20" is a huge number. At this point, it's not even clear if the vaccines stop you becoming infected in the first place, or just reduces your symptoms. In that case, a vaccinated person is no better for transmission than an unvaccinated, "asymptomatic carrier".
        Symmetry 6y ago
        I chose that number because people who are infected but remain asymptomatic through their infection seem to cause 20 times fewer infections according to a couple of contact tracing studies I saw. It seems pretty clear that the amount of fluid you have to get from an infected person, droplet or aerosol, has to be inversely proportional to their viral load if you're to get infected. Current guesses of an infectious dose I've seen are 100 to 1000 virions via the aerosol route. We can see that different people reach peak viral loads that are orders of magnitude apart which helps make sense of why this disease has such a high k, driven by superspreaders whereas half of people fail to infect anyone else even without protective measures.
        ppf 6y ago
        So if I promise to isolate myself if I get symptoms, and am not concerned about Covid, why should I get vaccinated?
        Symmetry 6y ago
        It's the people who remain asymtomatic through their infections who barely infect others. For people who end up becoming symptomatic their viral load and infectiousness peaks somewhere in the day before symptoms first appear. That's the one thing we've found about this virus so far that's genuinely weird. It seems to be very good at evading the automatic immune system but once the Interferon starts flowing the viral population starts crashing immediately.
samastur 6y ago
Yes, that's often neglected. However this paper states that the lack of severe reactions may be down to the age of participants (around 30 years) so it is basically unknown if it reduces those.
kolinko 6y ago
If the vaccine doesn’t protect from mild symptoms, there is no reason to think it would protect from severe.
- dbetteridge 6y ago
  I mean if you actually read the published data that is categorically wrong. The variant in question escapes Antibody detection, but T-Cells still seem to provide significant protection against severe disease and death. https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab083/6124512 https://academic.oup.com/cid/advance-article/doi/10.1093/cid... https://www.biorxiv.org/content/10.1101/2021.03.11.435000v1 https://www.biorxiv.org/content/10.1101/2021.03.11.435000v1 The main published results aren't yet from human scale studies but here is one in hamsters showing a comparison in organ damage and results between unvaccinated and vaccinated with the Oxford/AZ vaccine.