NEW—A single dose of Oxford-AstraZeneca #COVID19 vaccine provided strong protection in trials after the first 22 days: 76% efficacy (days 22-90). Also, when 2nd shot were delayed by >3 months: ~82% efficacy for symptomatic disease. But poor efficacy for asymptomatic disease.

2) And stronger effect for longer time gap was also supported by stronger neutralization in pseudovirus assays that showed improvements with longer gap. Thus, not a fluke. Longer time gap >12 weeks, the stronger vaccine effects. https://poseidon01.ssrn.com/delivery.php?ID=535088111116103123006002093123091122032020077035034062072043003034017032004104058043094038068068117125123110053075115068088087018028085015015001040097102072079043093005055088092118110088095096110021057123071038064091002066086123086092103124022008105087077083124072099016105075090092066000127&EXT=pdf&INDEX=TRUE

3) Visualized in specific days, it is apparent there is an overall rise in efficacy after 90 days, though it gets thin in the extreme tails.

But in panel C with the low 1st dose, standard 2nd dose, maybe efficacy does seemingly climb into the mid 90s% (exploratory analysis)

4) As for asymptomatic infection, there was no observed benefit other than a narrow vaccination case of low 1st dose, stands 2nd dose group with 12 week gap between doses—47% efficacy, significant. But overall there wasn’t a strong trend found in standard dose.

5) And indeed, DELAYING THE SECOND DOSE of the Oxford AZ vaccine behind 12 weeks seems favorable. https://www.nytimes.com/live/2021/02/02/world/covid-19-coronavirus/new-data-on-the-astrazeneca-oxford-vaccine-lend-support-for-delaying-its-second-doses

6) For the 1 single dose efficacy, one can see there is a pretty good 76% average efficacy for symptomatic #COVID19 from days 22-90. Very limited data for 90-120 days. And there is no real efficacy seen for asymptomatic illness after 21 days.

7) Meanwhile, here is the new Sputnik V vaccine trial data with ~20,000 people — found 91.6% efficacy. See thread for details. https://twitter.com/drericding/status/1356591721728126978

8) If we add in the 15k vaccinated in the Sputnik trial with the 75k previously, we now have 90,000 vaccinated in these #COVID19 trials with zero deaths! https://twitter.com/drericding/status/1356080282286379010

9) and to be clear, the vaccine does lower the risk of transmission, just not all transmission. But that is how most Prevention modalities work— it lowers the risk. Rarely does anything reduce risk by 100% - ie eliminate it, though the vaccines do seem to mostly eliminate death.

10) lowers total positive PCRs by 67%. That’s huge. https://news.sky.com/story/oxford-vaccine-may-have-67-effect-on-transmission-and-protection-remains-for-three-month-jab-interval-12206734