BREAKING—Oxford/Astrazeneca vaccine is 70% effective overall. But one of its dosing regimens of low-then-high yields 90% effectiveness.

Oxford #COVID19 vaccine cheaper than the Pfizer & Moderna vaccines, and does *not* does not require freezing transport. https://www.bbc.com/news/health-55040635

2) When volunteers were given two "high" doses the protection was 62%, but this rose to 90% when people were given a "low" dose followed by a high one. Not clear why yet.

The 90% effectiveness data was "intriguing" and would mean "we would have a lot more doses to distribute."

3) There were also lower levels of asymptomatic infection in the low followed by high dose group which "means we might be able to halt the virus in its tracks," Prof Pollard said.

In the UK there are 4 million doses ready to go, with another 96 million to be delivered.

4) “regimen that was 90 percent effective involved using a halved first dose and a standard second dose. Oxford also said that there were no or severe cases of the coronavirus in anyone who received the vaccine, & a reduction in asymptomatic infections” https://www.nytimes.com/live/2020/11/23/world/covid-19-coronavirus/drugmaker-becomes-the-third-major-vaccine-developer-to-announce-promising-results

5) Separately, IMPORTANT EXPLANATION to vaccine questions. @michaelmina_lab explains:

“why is a vaccine better source of immunity, if already have antibodies & T-Cell response?”

“How does vaccine give me more protection than some earlier immunity?” https://twitter.com/michaelmina_lab/status/1330381107595014146

6) As explained, a vaccine is more targeted to the #SARSCoV2 receptor while natural infection has a more “choose your own adventure” what parts of virus one develops antibodies to. Targeted likely better.

7) The analogy @michaelmina_lab explains is that natural infection can develop non-useful antibody recognition like to a less useful “pinky toe” part. https://twitter.com/drericding/status/1330471929610969088?s=21

8) Further, noted earlier that Pfizer & Moderna vaccines both showed better antibody binding & neutralization in vaccinated people in P1 trials, than convalescent natural infected cases.

another reason vaccine better than Scott Atlas’s “herd”. #COVID19 https://twitter.com/drericding/status/1330111548870832129

9) That said, Harvard immunologist Michael Mina is slightly unsure if the initial >90% efficacy of the vaccine will hold forever long term because immunity response is often stronger early on but plasmablasts can wane. https://twitter.com/michaelmina_lab/status/1328355643300917249?

10) press release here. I wished they put out full paper darn it. https://www.astrazeneca.com/content/astraz/media-centre/press-releases/2020/azd1222hlr.html

11) Two key takeaways why the Oxford vaccine could be better overall:

Refrigerator storage (no freezing needed, unlike the mRNA ones by Pfizer and Moderna)

Just $2.50 per dose for Oxford/AZ vaccine ($15 a dose per US govt paid for the mRNA vaccine). #COVID19

12) actually, the Pfizer vaccine is $20/dose while Moderna is $15-25 per dose.

Oxford AZ vaccine? Just $2.50.

13) We aren’t entirely certain why the half dose initial priming shot is better - but one scientist who developed the Oxford vaccine says it may be related to the ChAdOx1 adenovirus vector. Don’t worry—no chimpanzee involved in the vaccine. https://www.sciencemag.org/news/2020/11/another-covid-19-vaccine-success-candidate-may-prevent-further-coronavirus-transmission