1) Now that #Israel's Ministry of Health has released more info and data on the 64% estimate of #BionTech #Pfizer effectiveness against infection and symptomatic illness from #delta, my scepticism about this estimate remains fairly intact. Why?
https://twitter.com/AndreasShrugged/status/1412133138164326400
2) With #delta spreading, I would expect an uptick in infections and symptomatic illness also among the unvaccinated. But this hasn't happened, essentially. Vaccination rate was fairly stable in IL during this period, so no change in group sizes. Previously infected are excluded. 
3) In relative terms, infections have increased 6-fold among the vaccinated but decreased by 17% among the unvaccinated. This seems very counterintuitive during the spread of a more infectious variant - if all other variables had been held constant and they probably haven't been.
4) Many potential variables may affect the occurrence, detection and reporting of infections among the vaccinated more than among the unvaccinated: socio-economic and demographic characteristics, higher exposure of the vaccinated to #delta, behavior, idiosyncratic events...
5) I'm not doubting the actual effectiveness calculations from the data, but I have doubts whether the data really provided good "apples-to-apples" groups here. Feel free to weigh in, @ashishkjha @JamesWard73 @nataliexdean ... Full PM by Israeli MoH: gov.il/en/departments…
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