3 ms·

I am a concerned citizen and parent. I only have so much time to write a well source comments. I wish people were applying just as much critical carefulness wit

I am a concerned citizen and parent. I only have so much time to write a well source comments. I wish people were applying just as much critical carefulness with regard to CDC publications. Where is the CDC longitudinal VE study? Do they even track VE data over time? Why do I have to sift through data instead of "the experts"? Let's look at the weekly UK vaccine surveillance report, week 36 vs. week 42, afaik both within the UK Delta wave. For VE against severe disease, let's look at 'Deaths within 28 days of first positive COVID-19 test by date of death' tables. Let's pick age group 40-49 (older parents) and compute VE = 1 - vax_ratio / unvax_ratio. week 36, VE = 1 - 0.4 / 3.1 = 87% week 42, VE = 1 - 0.5 / 2.0 = 75% Notice something? Same for all other age groups. Same for all the intermediate VE reports. A small but constant gradual VE decline. FWIW, none of this makes me any happy. I wish the vaccines were holding effectiveness, that we didn't need a booster within 1 year of the initial shots and that the pandemic was over. Alas, reality does not cooperate. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1016465/Vaccine_surveillance_report_-_week_36.pdf https://assets.publishing.service.gov.uk/government/uploads/... https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1027511/Vaccine-surveillance-report-week-42.pdf https://assets.publishing.service.gov.uk/government/uploads/...

blackbear_ 5y ago
It's not so simple, you need to look at the total number of people in each age group or you may fall victim of Simpson's paradox [1] (as both of those reports say): > These data should be considered in the context of vaccination status of the population groups shown in the rest of this report. The vaccination status of cases, inpatients and deaths is not the most appropriate method to assess vaccine effectiveness and there is a high risk of misinterpretation. Vaccine effectiveness has been formally estimated from a number of different sources and is described earlier in this report. In particular, the reduction of death rates among non vaccinated over time may be caused by natural selection, i.e. the weak died already while the remaining ones have unusually strong immune system (aka survivorship bias [2]). There may be other unaccounted confounders, too, such as a change of behaviour over time where the degree of change is dependent on the age group and/or vaccination status. For example, an apparent reduction of effectiveness for younger people may be caused by them going back to work/study, thus increasing their probability of getting infected, while older folks staying in care homes as before. Funnily enough, both Simpson's paradox and uncorrected confounders can result in observed correlations that are opposite to the real causality effect. And to clarify, I'm not saying your VE numbers there are wrong, just warning readers about the dangers of statistics. [1] https://plato.stanford.edu/entries/paradox-simpson/ https://plato.stanford.edu/entries/paradox-simpson/ [2] https://en.wikipedia.org/wiki/Survivorship_bias https://en.wikipedia.org/wiki/Survivorship_bias
- angelzen 5y ago
  I agree! Another reason why VE appears to decrease might be that the ratio of unvax population with prior infection might be growing, and it's a wash between vax and post infection natural immunity. OTOH this is not an isolated data point. We have: the booster push (why?), the veteran study, the PHE data. Something doesn't add up. For whatever reasons, the observed epi VE, after all the confouding factors are accounted by reality, is fading for both infection and severe infection, though VE agains severe infection is fading at a slower rate. To the point of J&J VE against infection (the weakest of the bunch) being almost gone in 6 months. I don't have a time machine, but I'm really interested to see how the Jan 2022 VE numbers hold up across the board. Given OAS concerns (please re-read the dengue study excerpt I already quoted), near zero covid risk for kids, rapidly fading VE against infection and the general lack of long term data about covid & immune system (no time machines), what exactly is the rush to vaccinate kids against the original variant?! And why do we pretend we can just tweak vaccines to any new variant, when, while technologically we can concoct any protein we like, the immune system doesn't turn on a dime?

blackbear_ 5y ago

It's not so simple, you need to look at the total number of people in each age group or you may fall victim of Simpson's paradox [1] (as both of those reports say): > These data should be considered in the context of vaccination status of the population groups shown in the rest of this report. The vaccination status of cases, inpatients and deaths is not the most appropriate method to assess vaccine effectiveness and there is a high risk of misinterpretation. Vaccine effectiveness has been formally estimated from a number of different sources and is described earlier in this report. In particular, the reduction of death rates among non vaccinated over time may be caused by natural selection, i.e. the weak died already while the remaining ones have unusually strong immune system (aka survivorship bias [2]). There may be other unaccounted confounders, too, such as a change of behaviour over time where the degree of change is dependent on the age group and/or vaccination status. For example, an apparent reduction of effectiveness for younger people may be caused by them going back to work/study, thus increasing their probability of getting infected, while older folks staying in care homes as before. Funnily enough, both Simpson's paradox and uncorrected confounders can result in observed correlations that are opposite to the real causality effect. And to clarify, I'm not saying your VE numbers there are wrong, just warning readers about the dangers of statistics. [1] https://plato.stanford.edu/entries/paradox-simpson/ https://plato.stanford.edu/entries/paradox-simpson/ [2] https://en.wikipedia.org/wiki/Survivorship_bias https://en.wikipedia.org/wiki/Survivorship_bias

angelzen 5y ago
I agree! Another reason why VE appears to decrease might be that the ratio of unvax population with prior infection might be growing, and it's a wash between vax and post infection natural immunity. OTOH this is not an isolated data point. We have: the booster push (why?), the veteran study, the PHE data. Something doesn't add up. For whatever reasons, the observed epi VE, after all the confouding factors are accounted by reality, is fading for both infection and severe infection, though VE agains severe infection is fading at a slower rate. To the point of J&J VE against infection (the weakest of the bunch) being almost gone in 6 months. I don't have a time machine, but I'm really interested to see how the Jan 2022 VE numbers hold up across the board. Given OAS concerns (please re-read the dengue study excerpt I already quoted), near zero covid risk for kids, rapidly fading VE against infection and the general lack of long term data about covid & immune system (no time machines), what exactly is the rush to vaccinate kids against the original variant?! And why do we pretend we can just tweak vaccines to any new variant, when, while technologically we can concoct any protein we like, the immune system doesn't turn on a dime?