5 ms·

It seems like this study has two groups of 400, so 800 people total, 1% of which had the South African variant, so 8 people. How can we draw any conclusions fro

by b3n 5y ago

It seems like this study has two groups of 400, so 800 people total, 1% of which had the South African variant, so 8 people. How can we draw any conclusions from this?

TeeMassive 5y ago
And the vaccine is about 95% effective, which means around 40 people not immunized. This is meaningless.
- throwaway4good 5y ago
  No. It is not meaningless. Had the vaccine had the same efficacy on the various variants, the ratio between them would have been the same. However it is not, indicating that the vaccine is vastly (factor of 8) more effective on the main variant compared to the SA / Brazil variants. Hence the conclusion. It could do with more data but that has also been the case for similar studies of the AstraZenaca vaccine.
  - Method-X 5y ago
    Wouldn’t you need more than 800 people to get a statistically significant result?
    - throwaway4good 5y ago
      They check for significance in the paper. There is no magical sample size number. It depends on the size of the effect which here appears to be quite strong so a smaller sample would actually do.
  - TeeMassive 5y ago
    There's a factor of 8 because there are 8 variant cases. This is meaningless.
- tzs 5y ago
  Is vaccine effectiveness per person or per infection opportunity? In other words, does 95% effective mean that if you took a large group vaccinated people and once a day had an infected person have a massive coughing and sneezing fit right into their faces, 95% would never get infected by that and 5% would? Or does it mean that they would all get infected, but it would take on average 20 times as long as it would have had they not been vaccinated?
  - teeray 5y ago
    It means that in the study submitted to the FDA, the vaccine group had 8 cases and the control group had 162 cases [0]. 8 / 162 = ~5% of the cases in the vaccine group, ergo 95% effectiveness (or more specifically Relative Risk Reduction). [0] https://www.nejm.org/doi/full/10.1056/NEJMoa2034577 https://www.nejm.org/doi/full/10.1056/NEJMoa2034577

by b3n 5y ago

It seems like this study has two groups of 400, so 800 people total, 1% of which had the South African variant, so 8 people. How can we draw any conclusions from this?

TeeMassive 5y ago

And the vaccine is about 95% effective, which means around 40 people not immunized. This is meaningless.

throwaway4good 5y ago
No. It is not meaningless. Had the vaccine had the same efficacy on the various variants, the ratio between them would have been the same. However it is not, indicating that the vaccine is vastly (factor of 8) more effective on the main variant compared to the SA / Brazil variants. Hence the conclusion. It could do with more data but that has also been the case for similar studies of the AstraZenaca vaccine.
- Method-X 5y ago
  Wouldn’t you need more than 800 people to get a statistically significant result?
  - throwaway4good 5y ago
    They check for significance in the paper. There is no magical sample size number. It depends on the size of the effect which here appears to be quite strong so a smaller sample would actually do.
- TeeMassive 5y ago
  There's a factor of 8 because there are 8 variant cases. This is meaningless.
tzs 5y ago
Is vaccine effectiveness per person or per infection opportunity? In other words, does 95% effective mean that if you took a large group vaccinated people and once a day had an infected person have a massive coughing and sneezing fit right into their faces, 95% would never get infected by that and 5% would? Or does it mean that they would all get infected, but it would take on average 20 times as long as it would have had they not been vaccinated?
- teeray 5y ago
  It means that in the study submitted to the FDA, the vaccine group had 8 cases and the control group had 162 cases [0]. 8 / 162 = ~5% of the cases in the vaccine group, ergo 95% effectiveness (or more specifically Relative Risk Reduction). [0] https://www.nejm.org/doi/full/10.1056/NEJMoa2034577 https://www.nejm.org/doi/full/10.1056/NEJMoa2034577