True that there is “no data” from their trial, but plenty of reasons to think that protection will last longer than 21 days based on (a) our understanding of the mechanism (b) experience with vaccines for other pathogens.
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Replying to @macrocephalopod @econhedge
eg AstraZeneca vaccine *was* tested in a one dose regime and protection was as good (actually better) than two dose regime, up to the point they stopped the trial. Are there reasons to think that the Pfizer vaccine is different?
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Replying to @macrocephalopod
Pfizer is a 2 dose vaccine. In the trial some participants caught the virus between getting the first and second dose and one dose was found to be 52% effective.
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Replying to @econhedge
Almost everyone who caught the virus after the first dose caught it within the first ten days, when you would not expect much if any immunity. Between 10 and 21 days it was nearly as effective as in the period following the second dose.
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Replying to @macrocephalopod
The difference is big. https://www.bmj.com/content/371/bmj.m4826 …
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Replying to @econhedge @macrocephalopod
But as
@macrocephalopod said - that’s all about timing. Those cases were in the short period after first dose and before we’d expect it to be working anyway. There’s no evidence about rates after would expect immunity.1 reply 0 retweets 0 likes -
Replying to @1867ben @macrocephalopod
What do you think we are taking about ... we are talking exactly about timing
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Replying to @econhedge @1867ben
Look at the difference in the slope of the lower line between 0 to 10 days and 10 to 21 days. Second dose is not administered till 21 days but protection has obviously kicked in before that.pic.twitter.com/sstcFj9MJI
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I understand what you're saying, and you may well be right. But it seems extremely risky to change a national distribution strategy based solely on the idea of extrapolating the red line from days 10-21 and assuming it remains flat.
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Yep understand that there are risks and data is limited. But the decision is not only based on this data - trials of other covid vaccines, other metrics from these trials (eg antibody production) and what we know about vaccines in general 1/2
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...points to this path being worth trying. It’s higher risk/higher reward for sure, but lots of people smarter than me think it’s worth it. It’s certainly not obviously the wrong thing to do.
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Replying to @macrocephalopod @pennma2 and
(fwiw many of my doctor friends agree with me but my wife, a consultant paediatrician, would prefer to prioritise two doses. So clearly there is reasonable disagreement!)
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Thanks appreciate the thoughtful response. Going this route - doubling the distribution coverage but making assumptions about effectiveness outside of the study - is politically high risk. Seems more downside than upside risk to me (from a political standpoint)
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