Unofficial unnamed AstraZeneca insider says they are doing the interim analysis for the US trial of the Oxford vaccine. AstraZeneca spokesperson says 4-6 weeks till data release. reuters.com/article/uk-hea… One is wrong? Or they'll release only when have FDA minimum follow-up?
..With results for AstraZeneca's large trial of the Oxford vaccine on the horizon ⬆️, some things I'm keeping in mind. It's a single, adequately powered, standardized, double-blind, fully placebo-controlled trial: the first for this vaccine. It's 2 doses, 4 weeks apart, so...2/8
...not designed to test the hypothesis that 8-week or 12-week interval increases efficacy. But as with other large vaccine trials, there'll be data relevant to onset of immunity to chew on. It's 2:1 randomization (twice as many in vax as placebo), final goal 150 events...3/8
...Participants will be different to the earlier trials. 24% of participants are 65 or older - a dramatic difference, for a critical question. If efficacy is less >65 - & that's a totally open question - it could lower overall efficacy. Complicated...4/8 s3.amazonaws.com/ctr-med-7111/D…
...UK/Brazil 90% healthcare & social workers: won't be in US. thelancet.com/journals/lance… Could have an influence, eg even increasing efficacy: hypothesis for CoronaVac was HCWs depressed efficacy by diagnosing many very mild infections: perhaps? (see absolutelymaybe.plos.org/2021/01/31/var…)...5/8
...The diversity should be higher - eg the UK trial had <1% Black people & it's 10% in the US trial: that could influence efficacy too. (Everyone calls it "the US trial", but there are some participants from Latin America too, though not Brazil)....6/8
https://twitter.com/NedPagliarulo/status/1354452241902657543
..Then there's placebo control. A trial in Cuba is testing hypothesis that meningococcal vaccine boosts innate immunity & protects against Covid-19 rpcec.sld.cu/en/trials/RPCE… *Long* shot, but if it does at all, that control in the other trials may have reduced apparent efficacy..7/8
...Latest data for standard doses: 63% (52-72%), with some possible lowering from "UK" variant (maybe "SA" too?). So many moving parts! US trial could be similar, but with much greater certainty - or lower. Could be higher. 🤞 8/8 papers.ssrn.com/sol3/papers.cf…, papers.ssrn.com/sol3/papers.cf…
Report that "SA" variant considerably reduces the Oxford/AstraZeneca vaccine's efficacy
https://twitter.com/janinegibson/status/1358151228203683854
Context for the question of impact of the "SA" variant for the Oxford/AstraZeneca data: numbers in SA are small. It was a phase 1/2 trial, with results for 1,476 people to the latest data reported (45 of whom had a single shot). papers.ssrn.com/sol3/papers.cf…
Confirmation on the report of reduced efficacy against mild & moderate "SA" variant: AstraZeneca stressing efficacy against severe disease & subgroup data on dosing intervals reuters.com/article/uk-hea… HT @sailorrooscout
...Additional context on the issue of the SA trial: the median age was reportedly 31 - so it's not a group at high risk of severe outcomes. (Note: 2,000 enrolled &c doesn't mean that they are all in the analysis that will be reported.) 
...Oxford issued a press release with some data, & announced they are working on trying to develop a version that can target new variants. South Africa has halted its rollout of the Oxford/AstraZeneca vaccine. ox.ac.uk/news/2021-02-0…, wsj.com/articles/astra… 1/n
...The SA trial was too small to provide conclusive answers. The press release doesn't say how many people are in the analysis, but the most recent they released analyzed 1,476 of the approx 2,000 participants...2/n
https://twitter.com/hildabast/status/1358188734647214080
...The Oxford press release doesn't include any numbers - just says that it didn't provide protection against mild to moderate Covid-19 caused by B.1.351 ("SA" variant) was "minimal" & the study was too small for them to assess severe disease: with an average age of 31,...3/n
...& such a small group, you wouldn't expect anyone to get severely ill. Here's the efficacy calculation. No appreciable difference, based on 39 people with symptomatic Covid-19, an efficacy rate of 10.4% with extreme uncertainty: CI range -79 to 55...4/n
https://twitter.com/HelenBranswell/status/1358472144162799632
... Protection against moderate to severe Covid-19 was reduced in SA overall for the J&J vaccine (57%), but data on the variant specifically not released yet... 5/n
https://twitter.com/hildabast/status/1355148269693718529
...For the Novavax vaccine, efficacy in SA was 49% - with 27/44 events of disease sequenced, 93% were caused by the variant...6/n ir.novavax.com/news-releases/…
...Shabir Madhi @ShabirMadh, from Witwatersrand @WitsUniversity, who runs the SA trial, said this shifts their expectations of vaccine in SA to reducing severe disease instead of aiming for community immunity at this point...7/7
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