4 ms·

AstreZeneca showed 70% efficacy in the general population. Does this qualify as “far more effective” when the mRNA vaccines showed 95% efficacy?

jimmydorry 6y ago
The pfizer vaccine looks to be sitting closer to 30%[1] than 95% based on the parts of their trial data they are choosing to release. >With 20 times more suspected than confirmed cases, this category of disease cannot be ignored simply because there was no positive PCR test result. Indeed this makes it all the more urgent to understand. A rough estimate of vaccine efficacy against developing covid-19 symptoms, with or without a positive PCR test result, would be a relative risk reduction of 19% (see footnote)—far below the 50% effectiveness threshold for authorization set by regulators. [1] https://blogs.bmj.com/bmj/2021/01/04/peter-doshi-pfizer-and-modernas-95-effective-vaccines-we-need-more-details-and-the-raw-data/ https://blogs.bmj.com/bmj/2021/01/04/peter-doshi-pfizer-and-...
- sterlind 6y ago
  > Even after removing cases occurring within 7 days of vaccination (409 on Pfizer’s vaccine vs. 287 on placebo), which should include the majority of symptoms due to short-term vaccine reactogenicity, vaccine efficacy remains low: 29% (see footnote). The 95% claim assumes you've had both doses and five weeks have passed since the first dose. I don't think that's a fair way to dice the data. Also, "covid-19 symptoms" (the proxy that opinion writer used) are very non-specific. Headache, sore throat, cough - there's myriad causes. That's why PCR+ is the only way to get a decent signal. This seems like a crackpot analysis, not that I'm an expert. Oh, and finally, relative risk reduction (that number you're quoting) is a fundamentally different property than efficacy. It's the difference between the placebo and vaccine groups in catching covid. Relative risk reduction would only equal efficacy if 100% of the placebo group caught it.
  - jimmydorry 6y ago
    Not everything you disagree with is a crackpot analysis. >The BMJ is a weekly peer-reviewed medical trade journal, published by the trade union the British Medical Association (BMA). The BMJ has editorial freedom from the BMA. It is one of the world's oldest general medical journals. [1] >Peter Doshi is an associate editor at said journal. He completed a fellowship in comparative effectiveness research at Johns Hopkins and received his Ph.D. in history, anthropology, and science, technology and society from the Massachusetts Institute of Technology. [2] I could not quote the entire article, but as we all know, failing to quote any of it usually ends up with a majority not being aware of any content within the article. The key finding is that further investigation is required into the substantial portion of people with COVID-like symptoms that occured in both the experimental and placebo groups, which has not been adequately analyzed. The entire article addressed VE (measured by calculating the risk of disease among vaccinated and unvaccinated persons and determining the percentage reduction in risk of disease among vaccinated persons relative to unvaccinated persons) and showed the raw numbers which allows anyone else to reach the same calculation result. [1] https://en.wikipedia.org/wiki/The_BMJ https://en.wikipedia.org/wiki/The_BMJ [2] https://www.bmj.com/about-bmj/editorial-staff/peter-doshi https://www.bmj.com/about-bmj/editorial-staff/peter-doshi
    - sterlind 6y ago
      You compared 95% (the Pfizer efficacy number) to 29% (the relative risk reduction number calculated by that article.) That is incorrect. You should acknowledge that.
      - jimmydorry 6y ago
        I originally said it looks closer to 30% than 95% based on the limited data we have available, which anyone can do using the data in the article (and can even take a step further verify that these numbers came from the FDA's report). Vaccine Effectiveness (as defined by the CDC [1]) is calculated by: (Risk among unvaccinated group − risk among vaccinated group) / Risk among unvaccinated group Vaccine participants: 18198 Placebo: 18325 Confirmed COVID on vaccine: 8 Confirmed COVID on placebo: 162 Suspected COVID on vaccine (excl. Within 7 days of dose): 1185 Suspected COVID on placebo (excl. Within 7 days of dose): 1407 VE = ( (1569 / 18325) - (1193 / 18198) ) / (1569 / 18325) = 23.43% [1] https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section6.html https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section6.html
garmaine 6y ago
Yes, actually. That’s right at the inflection point where each added percent effectiveness is maximally beneficial to herd immunity. E.g. the difference from 85% to 95% is much less important than 60% -> 70%.
- mlyle 6y ago
  ?? This is a crazy way to look at it. If R0 is 2.5, then you need to vaccinate (1 - 1/2.5) / .95 of the population = 63% to reach herd immunity. For a 60% effective vaccine, you get (1 - 1/2.5) / .6 = 100% of the population. Yes, the slope is slightly different but the rolloff is exceptionally gentle. There is a huge difference in practicality between even an 85% and 95% effective vaccine (70% of the population vs. 63% of the population). Not to mention that none of what we've measured is differences in transmissibility; it's quite possible that a 70% effective-against-symptomatic-illness vaccine only mitigates transmission rates by 35%, and thus can't reach herd immunity at any level of vaccination.
  - thesz 6y ago
    And for 50% effective vaccine and R0 of 2.5, one has to vaccinate what, (1-1/2.5)/0.5=1.2 or 120% of population? Please, correct your math. It is weirdly off.
    - sanxiyn 6y ago
      50% effective vaccine could lower R0 of 2.5 to 1.25 (2.5 * 50% = 1.25). That's R0 > 1, so it can't stop transmission.
    - clausz 6y ago
      No, it's not. It only means that with these given numbers it is impossible to reach herd immunity.
      - garmaine 6y ago
        Not impossible, just can't be done by vaccination alone. The remaining required percentage of the population would have to get immunity from getting sick. This is what I was getting at in the grandparent post. 50% -> 60% and 85% -> 95% might both seem like they protect 10% more of the population, but the qualitative effect on the spread of the pandemic and be quite different. 60% might be enough to get herd immunity (with masks and social distancing), while 50% is not. Both 85% and 95% are definitely enough to get herd immunity, so to some extent that added protection matters less.
ulfw 6y ago
It didn't show that. It showed 62%. 70% is a pooled result when you put the (too few) people into the calculation who got 90% efficacy, which scientists can't explain as that testing regimen was completely fucked up by Jenner and AZN (different dosage, different timing, different age group <55yr only). So it's hard to tell if it's really 90% (due to sample size) or WHY it might be more effective than the 62% number. The approvals so far for the AZN/Oxford vaccine have been for the full-full dose regimen, which has shown to be 62% effective only.

jimmydorry 6y ago

The pfizer vaccine looks to be sitting closer to 30%[1] than 95% based on the parts of their trial data they are choosing to release. >With 20 times more suspected than confirmed cases, this category of disease cannot be ignored simply because there was no positive PCR test result. Indeed this makes it all the more urgent to understand. A rough estimate of vaccine efficacy against developing covid-19 symptoms, with or without a positive PCR test result, would be a relative risk reduction of 19% (see footnote)—far below the 50% effectiveness threshold for authorization set by regulators. [1] https://blogs.bmj.com/bmj/2021/01/04/peter-doshi-pfizer-and-modernas-95-effective-vaccines-we-need-more-details-and-the-raw-data/ https://blogs.bmj.com/bmj/2021/01/04/peter-doshi-pfizer-and-...

sterlind 6y ago
> Even after removing cases occurring within 7 days of vaccination (409 on Pfizer’s vaccine vs. 287 on placebo), which should include the majority of symptoms due to short-term vaccine reactogenicity, vaccine efficacy remains low: 29% (see footnote). The 95% claim assumes you've had both doses and five weeks have passed since the first dose. I don't think that's a fair way to dice the data. Also, "covid-19 symptoms" (the proxy that opinion writer used) are very non-specific. Headache, sore throat, cough - there's myriad causes. That's why PCR+ is the only way to get a decent signal. This seems like a crackpot analysis, not that I'm an expert. Oh, and finally, relative risk reduction (that number you're quoting) is a fundamentally different property than efficacy. It's the difference between the placebo and vaccine groups in catching covid. Relative risk reduction would only equal efficacy if 100% of the placebo group caught it.
- jimmydorry 6y ago
  Not everything you disagree with is a crackpot analysis. >The BMJ is a weekly peer-reviewed medical trade journal, published by the trade union the British Medical Association (BMA). The BMJ has editorial freedom from the BMA. It is one of the world's oldest general medical journals. [1] >Peter Doshi is an associate editor at said journal. He completed a fellowship in comparative effectiveness research at Johns Hopkins and received his Ph.D. in history, anthropology, and science, technology and society from the Massachusetts Institute of Technology. [2] I could not quote the entire article, but as we all know, failing to quote any of it usually ends up with a majority not being aware of any content within the article. The key finding is that further investigation is required into the substantial portion of people with COVID-like symptoms that occured in both the experimental and placebo groups, which has not been adequately analyzed. The entire article addressed VE (measured by calculating the risk of disease among vaccinated and unvaccinated persons and determining the percentage reduction in risk of disease among vaccinated persons relative to unvaccinated persons) and showed the raw numbers which allows anyone else to reach the same calculation result. [1] https://en.wikipedia.org/wiki/The_BMJ https://en.wikipedia.org/wiki/The_BMJ [2] https://www.bmj.com/about-bmj/editorial-staff/peter-doshi https://www.bmj.com/about-bmj/editorial-staff/peter-doshi
  - sterlind 6y ago
    You compared 95% (the Pfizer efficacy number) to 29% (the relative risk reduction number calculated by that article.) That is incorrect. You should acknowledge that.
    - jimmydorry 6y ago
      I originally said it looks closer to 30% than 95% based on the limited data we have available, which anyone can do using the data in the article (and can even take a step further verify that these numbers came from the FDA's report). Vaccine Effectiveness (as defined by the CDC [1]) is calculated by: (Risk among unvaccinated group − risk among vaccinated group) / Risk among unvaccinated group Vaccine participants: 18198 Placebo: 18325 Confirmed COVID on vaccine: 8 Confirmed COVID on placebo: 162 Suspected COVID on vaccine (excl. Within 7 days of dose): 1185 Suspected COVID on placebo (excl. Within 7 days of dose): 1407 VE = ( (1569 / 18325) - (1193 / 18198) ) / (1569 / 18325) = 23.43% [1] https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section6.html https://www.cdc.gov/csels/dsepd/ss1978/lesson3/section6.html

garmaine 6y ago

Yes, actually. That’s right at the inflection point where each added percent effectiveness is maximally beneficial to herd immunity. E.g. the difference from 85% to 95% is much less important than 60% -> 70%.

mlyle 6y ago
?? This is a crazy way to look at it. If R0 is 2.5, then you need to vaccinate (1 - 1/2.5) / .95 of the population = 63% to reach herd immunity. For a 60% effective vaccine, you get (1 - 1/2.5) / .6 = 100% of the population. Yes, the slope is slightly different but the rolloff is exceptionally gentle. There is a huge difference in practicality between even an 85% and 95% effective vaccine (70% of the population vs. 63% of the population). Not to mention that none of what we've measured is differences in transmissibility; it's quite possible that a 70% effective-against-symptomatic-illness vaccine only mitigates transmission rates by 35%, and thus can't reach herd immunity at any level of vaccination.
- thesz 6y ago
  And for 50% effective vaccine and R0 of 2.5, one has to vaccinate what, (1-1/2.5)/0.5=1.2 or 120% of population? Please, correct your math. It is weirdly off.
  - sanxiyn 6y ago
    50% effective vaccine could lower R0 of 2.5 to 1.25 (2.5 * 50% = 1.25). That's R0 > 1, so it can't stop transmission.
  - clausz 6y ago
    No, it's not. It only means that with these given numbers it is impossible to reach herd immunity.
    - garmaine 6y ago
      Not impossible, just can't be done by vaccination alone. The remaining required percentage of the population would have to get immunity from getting sick. This is what I was getting at in the grandparent post. 50% -> 60% and 85% -> 95% might both seem like they protect 10% more of the population, but the qualitative effect on the spread of the pandemic and be quite different. 60% might be enough to get herd immunity (with masks and social distancing), while 50% is not. Both 85% and 95% are definitely enough to get herd immunity, so to some extent that added protection matters less.

ulfw 6y ago

It didn't show that. It showed 62%. 70% is a pooled result when you put the (too few) people into the calculation who got 90% efficacy, which scientists can't explain as that testing regimen was completely fucked up by Jenner and AZN (different dosage, different timing, different age group <55yr only). So it's hard to tell if it's really 90% (due to sample size) or WHY it might be more effective than the 62% number. The approvals so far for the AZN/Oxford vaccine have been for the full-full dose regimen, which has shown to be 62% effective only.