3 ms·

Take a look at this: https://web.archive.org/web/20210204143915/https://www.novavax.com/sites/default/files/2021-02/20210202-NYAS-Novavax-Final.pdf https://web.

Take a look at this: https://web.archive.org/web/20210204143915/https://www.novavax.com/sites/default/files/2021-02/20210202-NYAS-Novavax-Final.pdf https://web.archive.org/web/20210204143915/https://www.novav... Go to slide 28. This is Novavax's presentation of clinical trial results. As part of their phase 2 trial in South Africa at the end of 2020, they gave everyone antibody tests. In the placebo arm, 30% of that arm was seropositive (had antibodies from a prior infection). Of the seronegative group, 2.9% contracted COVID during the study. Of the seropositive group, 2.9% contracted COVID during the study. At the time, most infections in SA were the B.1.351 variant (referred to in the presentation as 501Y.V2). This variant has many of the same mutations as P.1 and is believed to have a similar ability to evade immunity.

wk_end 6y ago
I'm sorry - a preliminary trial for a vaccine that's not currently in widespread use being ineffective against a different variant makes a pretty flimsy case for the danger of reinfection with P1. And actually, Novavax later announced that actually, natural immunity does provide protection against the SA variant [1]: > A previously reported initial analysis from the study through 60 days indicated that prior infection with the original COVID-19 strain might not completely protect against subsequent infection by the variant predominantly circulating in South Africa. However, the complete analysis of the South Africa trial indicates that there may be a late protective effect of prior exposure with the original COVID-19 strain. In placebo recipients, at 90 days the illness rate was 7.9% in baseline seronegative individuals, with a rate of 4.4% in baseline seropositive participants. Moreover: the SA variant and P.1 aren't necessarily similar in terms of immunity evasion. For instance: SA isn't using the AZ vaccine at all because of how ineffective it is against their variant, but it works just fine against P.1. Or look at this paper [2]: > Neutralization titres against P.1 were similar to those against B.1.1.7 and only a minority of samples failed to reach 100% neutralization at 1:20 dilution of serum, considerably better than neutralization of B.1.351, where titres were reduced 7.6-fold and 9-fold for the BNT162b2 Pfizer and ChAdOx1 nCoV-19 AstraZeneca vaccines respectively. [1] https://ir.novavax.com/news-releases/news-release-details/novavax-confirms-high-levels-efficacy-against-original-and-0 https://ir.novavax.com/news-releases/news-release-details/no... [2] https://www.biorxiv.org/content/10.1101/2021.03.12.435194v1 https://www.biorxiv.org/content/10.1101/2021.03.12.435194v1
- cameldrv 6y ago
  I'm not talking about the vaccine aspect of the trial, just the placebo arm where they did the antibody tests. I hadn't seen their 90 day update, so thanks for that. Your original statement that there were few documented reinfections. They found 30 of them here under controlled study conditions, and prior infection provided less than 50% protection against B.1.351. To my knowledge, there hasn't been a controlled study like this in Brazil. The in vitro results you cited suggest that while the immune escape of P.1 is not as great as B.1.351, it still is very substantial, and reinfection will occur in a substantial number of patients.
  - wk_end 6y ago
    Per the Washington Post just two days ago [1], there have been just 71 confirmed reinfections worldwide, which is why I made that claim. Unless half of those came from that study, I’m not really sure how to square this. I disagree with your assessment of P.1 immune escape being “very substantial” based on those in vitro results. It’s on par with the UK variant, which has no evidence - real world or otherwise - or reputation at all for widespread reinfection or vaccine escape. Never mind that in vitro results don’t even tell the whole story of an in vivo immune response. To be perfectly honest, I’m struggling to see how you’re making that claim. [1] https://www.washingtonpost.com/business/can-you-get-covid-twice-what-reinfection-cases-really-mean/2021/04/11/1c738674-9b29-11eb-b2f5-7d2f0182750d_story.html https://www.washingtonpost.com/business/can-you-get-covid-tw...
    - cameldrv 6y ago
      Washington Post cited BNO news, which is just one guy I believe. I don't know if he's just sourcing these from news stories or what. If they're seeing 30 reinfections over 3 months in 650 study participants, you can be quite sure that there are a lot more than 71 reinfections in the world.

wk_end 6y ago

I'm sorry - a preliminary trial for a vaccine that's not currently in widespread use being ineffective against a different variant makes a pretty flimsy case for the danger of reinfection with P1. And actually, Novavax later announced that actually, natural immunity does provide protection against the SA variant [1]: > A previously reported initial analysis from the study through 60 days indicated that prior infection with the original COVID-19 strain might not completely protect against subsequent infection by the variant predominantly circulating in South Africa. However, the complete analysis of the South Africa trial indicates that there may be a late protective effect of prior exposure with the original COVID-19 strain. In placebo recipients, at 90 days the illness rate was 7.9% in baseline seronegative individuals, with a rate of 4.4% in baseline seropositive participants. Moreover: the SA variant and P.1 aren't necessarily similar in terms of immunity evasion. For instance: SA isn't using the AZ vaccine at all because of how ineffective it is against their variant, but it works just fine against P.1. Or look at this paper [2]: > Neutralization titres against P.1 were similar to those against B.1.1.7 and only a minority of samples failed to reach 100% neutralization at 1:20 dilution of serum, considerably better than neutralization of B.1.351, where titres were reduced 7.6-fold and 9-fold for the BNT162b2 Pfizer and ChAdOx1 nCoV-19 AstraZeneca vaccines respectively. [1] https://ir.novavax.com/news-releases/news-release-details/novavax-confirms-high-levels-efficacy-against-original-and-0 https://ir.novavax.com/news-releases/news-release-details/no... [2] https://www.biorxiv.org/content/10.1101/2021.03.12.435194v1 https://www.biorxiv.org/content/10.1101/2021.03.12.435194v1

cameldrv 6y ago
I'm not talking about the vaccine aspect of the trial, just the placebo arm where they did the antibody tests. I hadn't seen their 90 day update, so thanks for that. Your original statement that there were few documented reinfections. They found 30 of them here under controlled study conditions, and prior infection provided less than 50% protection against B.1.351. To my knowledge, there hasn't been a controlled study like this in Brazil. The in vitro results you cited suggest that while the immune escape of P.1 is not as great as B.1.351, it still is very substantial, and reinfection will occur in a substantial number of patients.
- wk_end 6y ago
  Per the Washington Post just two days ago [1], there have been just 71 confirmed reinfections worldwide, which is why I made that claim. Unless half of those came from that study, I’m not really sure how to square this. I disagree with your assessment of P.1 immune escape being “very substantial” based on those in vitro results. It’s on par with the UK variant, which has no evidence - real world or otherwise - or reputation at all for widespread reinfection or vaccine escape. Never mind that in vitro results don’t even tell the whole story of an in vivo immune response. To be perfectly honest, I’m struggling to see how you’re making that claim. [1] https://www.washingtonpost.com/business/can-you-get-covid-twice-what-reinfection-cases-really-mean/2021/04/11/1c738674-9b29-11eb-b2f5-7d2f0182750d_story.html https://www.washingtonpost.com/business/can-you-get-covid-tw...
  - cameldrv 6y ago
    Washington Post cited BNO news, which is just one guy I believe. I don't know if he's just sourcing these from news stories or what. If they're seeing 30 reinfections over 3 months in 650 study participants, you can be quite sure that there are a lot more than 71 reinfections in the world.