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Its a technical & medical term, rather than one that is meant to be useful for broader discussion. Efficacy in vaccines == people who were prevented from being
by clomond 6y ago
Its a technical & medical term, rather than one that is meant to be useful for broader discussion.
Efficacy in vaccines == people who were prevented from being confirmed COVID positive (symptoms sufficient to prompt a test, leading to a positive result)
Therefore, a 91% effective metric for vaccines means that 91% of those who receive that vaccine are expected to NOT contract COVID 'at all'. Thing is though, many vaccines broadly do not prevent disease but shift the severity upon contraction.
The metric that is actually useful for informing the public and policy is the answer to the question of 'does this prevent hospitalization, severe disease and death?'. Broadly speaking most approved vaccines globally have near 100% effectiveness in this.
- _Gyan_ 6y agoThe primary endpoint is symptomatic infection, not any infection per se. And it's a bit of a kludge, as all the Phase III protocols I've read define symptomatic infection as X no. of symptoms for Y+ no. of days i.e. there are people with fewer symptoms who aren't counted (or even tested to check for infection). The efficacy is the 1-relative risk of the primary endpoint.
- throwaway894345 6y ago> Therefore, a 91% effective metric for vaccines means that 91% of those who receive that vaccine are expected to NOT contract COVID 'at all'. Thing is though, many vaccines broadly do not prevent disease but shift the severity upon contraction. But I was just reading about another study of medical personnel who were taking periodic COVID tests so as to catch asymptomatic transmission, and I believe this study (or maybe merely the media about it) also used "effectiveness".
- deleted 6y ago[deleted]