General Discussion
Related: Editorials & Other Articles, Issue Forums, Alliance Forums, Region ForumsChange urged to single vaccine dosing for Pfizer. Moderna not sure about South African variant
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eta: sorry, had to edit subject line, Pfizer did not say this. First tweet headline was wrong.
Yonnie3
(17,376 posts)Pobeka
(4,999 posts)I don't claim to understand the Pfizer protocols, but
a) If everyone got the two doses in the trials, and the dose spacing was 3-4 weeks, then what the article is claiming is that in the final 1 or 2 week period after the first dose, only 5% of the vaccinated individuals got symptoms. It would not give any way to assess efficacy beyond that 1 or 2 week period, because individuals got a second dose after a total period of 3-4 weeks, and there is no long term data to support an efficacy estimate for a single dose.
b) If some of the individuals in the trials only got a single dose, then this could be valid.
My guess if there was a second test group that only got one dose, Pfizer would already know the answer about the long term efficacy of a single dose and we'd have started with the one dose regimen.
Blue_true
(31,261 posts)Pfizer must have developed the one dose data from recently vaccinated people. And like you, I am trying to figure out what after 2 weeks mean, does that mean a person is good against SARS-COV-2 for as long as the people that get two doses, or does it mean that once the vaccine kicks in 2 weeks, a person is good for an as yet undetermined time?
Pobeka
(4,999 posts)There is no long term 1 dose study.
Answers the question.
https://pfe-pfizercom-d8-prod.s3.amazonaws.com/2020-11/C4591001_Clinical_Protocol_Nov2020.pdf
Caveat -- I haven't read the whole thing, but it appears that the phase I trial may have attempted to get some estimates from 1 dose (no -- see edit below), in subsequent phase 2/3 trials they only used 2 doses, which I assume means they learned 2 doses were required to get sufficient immunity.
on edit: -- even phase 1 protocol was 2 doses, according to the pdf referenced.
Blue_true
(31,261 posts)they had compelling data showing that one dose did the job.