Some results from Brazilian phase 3 trial for Sinovac's inactivated Covid vaccine CoronaVac released at a press conference. Vaccine efficacy for mild symptomatic Covid-19: 78%, similar in people under & over 60 years. 0 moderate/severe/hospitalized... 1/n…
...For background: it's a trial in healthcare workers. The protocol was published here:… Collection of records on this vaccine here:… ....2/n
...Currently buying it from China, US$10 a dose: more than the Oxford vaccine ($3), half of Tozinameran (BNT/Pfizer). However supply of Oxford vax uncertain, whereas they already have drug regulator clearance for local manufacture of CoronaVac... 3/n…
...Doesn't require super-freezing etc. Brazil plans to make up to 1m doses of CoronaVac a day, supplying several countries in the region.… Based on imports, 46m doses planned to be available in January ...4/n…
...Back to results. Only vague efficacy data today - presumably still waiting on Sinovac's announcement/publication of international results (Turkey & Indonesia as well as Brazil). Brazil: 12,476 people, 60 events in vax group vs 160 in placebo...5/n…
...Going back to the protocol, the primary efficacy endpoint was Covid-19 in anyone 2 weeks after the 2nd injection. For a final efficacy result, they needed 151 of those events: with 220, they've cleared that (the interim analysis would've been after 61 events)...6/n
...At the 9,000-person point, head of Butantan (public research & vaccine institute that ran the trial), said adverse events were low (as expected for inactivated vax): 35% of people mild-moderate, no severe or serious events, 10% headache, 4% fatigue..7/n…
...Fatigue less than 5% was also reported for the first 1,300 people in the Turkish trial of CoronaVac. That trial reportedly recruited its approx 13,000 participants in November. Indonesian trial is ca 1,600. ...8/n
..Critical question for full data, tho: how many people aged 60+? From what we know so far, 2 mRNA vaxes have considerably higher efficacy, with fewer/less severe adverse events (AEs) than the Oxford vax; CoronaVac has far fewer AEs, efficacy similar to or better than Oxford. 9/9

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More from @hildabast

5 Jan
MHRA's (UK drug regulator) 57-page Public Assessment Report on Oxford/AstraZeneca vax is out:… Like Oxford's publication, does not mention phase 3 trials in US & India (& so its serious adverse event), so not clear this is a selective trial report... 1/n
...Quality assessment of the drug & manufacturing facilities based on manufacturer reports & certifications, not MHRA inspections. Presumably as with Tozinameran (BNT/Pfizer vax), this would be done by the European Medicines Agency (EMA)...2/n
...Independent Batch Testing for the vaccine is undertaken UK National Institute for Biological Standards and Control (NIBSC). Temperature requirements confirmed (does not need super-freezing) ...3/n
Read 19 tweets
31 Dec 20
Statement from the UK Joint Committee on Vaccination & Immunisation (JCVI) on why they believe their strategy will achieve maximum impact:… 1/n
...They point out that most of the people who got sick with Covid-19 between 1st & 2nd doses of Tozinameran (BNT/Pfizer vax) did so in the 1st 2 weeks, so the efficacy after 2 weeks was 89% (95% CI 52-97%). But Pfizer stresses... 2/n
...that's only known for people who got their booster shot at 3 weeks, so it's unknown if it stays high for up to 3 months… For the Oxford/AstraZeneca vax, they rely on a subgroup analysis - but the data isn't provided...3/n
Read 5 tweets
30 Dec 20
#tbt This is the amazing Anna Wessels Williams (1863-1954) in the early 1900s. Her sister nearly died in childbirth in 1887: distressed by her treatment, she entered medical school. She moved to lab work in 1894: her 1st major breakthrough came fast ...1/4…
...While her boss was on vacation, she solved the barrier to high-yield diphtheria vaccines. She followed that with a 2-year sabbatical at the Pasteur Institute, creating a rabies vaccine that would be mass-produced in the US. Next was a rabies test in 1905 used for decades...2/4
...She was on the frontlines of the 1918 influenza pandemic, developed a more accurate diagnostic test for trachoma, & co-published a major textbook as well as one of the early successful science books for the public in 1937 ... 3/4
Read 4 tweets
29 Dec 20
Well, dear readers, my take on "the winning formula" for Oxford/AstraZeneca did not age well. According to the Indian manufacturing partner, it isn't the "low"-dose-1st subgroup. It's another subgroup, perhaps a subgroup of a subgroup...… HT @wogboy11 ..1/6
..The sweet spot he says is "a 2-to-3 months’ gap between dose 1 & dose 2". First let's recap their original data. They said intervals didn't make a difference. For the "standard"-"standard" group >8 wks apart vaccine efficacy was 65·6% (24·5 to 84·4). Ditto 6 weeks cutoff ..2/6
...The protocol doesn't limit the possible exploratory subgroup analyses ⬇️: so many ways they could have found a subgroup that hit this mark. Eg half the already-small "low"-dose-1st group had >12 wks apart: sliced off those perhaps? But I don't think that's the main point ..3/6
Read 6 tweets
28 Dec 20
MHRA verdict reportedly coming any day for the Oxford/AstraZeneca vaccine. I've been asked if I think their process is comparable to FDA's. Good question, post-Brexit. So I looked at 3 regulator reports for Tozinameran (BNT/Pfizer): FDA, MHRA, EMA (Europe) ...1/6
...2 agencies have unequivocal advantages:

1) Only the EMA did manufacturing inspections, which is a very big deal;

2) FDA had greater transparency: they're the only 1 releasing manufacturer briefing, released reports pre-committee, live-streamed committee discussion ...2/6
... FDA assessment report: 92 pages, almost all clinical data/issues, extensive data analysis - released days before their decision;

MHRA: 51 pages, not as much analysis - released 2 weeks after decision;

EMA: 140 pages, extensive data analysis, wide coverage ...3/6
Read 7 tweets
27 Dec 20
The AstraZeneca boss says they have new data for "the winning formula" that shows as good a result as Tozinameran (BNT/Pfizer) & Moderna. Based on what we know so far, is that likely? Well, yes...and no... 1/6…
...Protocol for their pooled analysis of trials had 2 analyses, dependent on reaching set events (people sick with Covid-19 more than 2 weeks after 2nd dose) in the standard-standard dose group: 53 events for the 1st analysis, 105 for the "final"... 2/6…
..We've seen 1st analysis: 98 events in that group. So they only needed a few more events to get to final of 105. Vaccine efficacy in that group was 62·1% (95% CI 41·0–75·7): with upper bound 75.7%, small data increase unlikely to get them over 90% ...3/6…
Read 7 tweets

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