Some things to keep in mind when you see people dumping on "low efficacy" of "Chinese Covid vaccines", particularly based on that single medium-sized trial in Brazil of doses only 2 weeks apart...1/n
...There's the obvious ones: the results of this trial aren't the whole picture - not of the trials that are underway, nor of the way the vaccine is being used (doses more than 2 wks apart)...2/n
...The efficacy against fearsome outcomes was good in this trial - a vaccine that could prevent over 80% of the worst outcomes & reduce the severity in a major way is incredibly needed in a world bereft of enough options...3/n
...Critically, though, the outcome we care about are the effectiveness ones: & that's not just about what a vaccine can do, it's to do with acceptance, as well. The trade-off of lower efficacy is a very, very low rate of adverse events...4/n
...If the combination of traditional type of vaccine & very low adverse events could translate into high vaccine acceptance, then that could make an important difference. That's still an if, but it's one that matters...5/n
...We're seeing very high rates of people in many countries not wanting Covid vaccines because of, in large part, concerns about adverse events & what that means, which is very complex & personal...6/n
...Then consider Serrana in Brazil, where they reckoned about 30,000 were eligible to be vaxed & tried to get them all to sign up for Sinovac's CoronaVac: 28,000 did & over 27,000 accepted both doses... 7/n
...Others have yet to show that they can get that level of vax acceptance - what? over 90% of non-pregnant, vax-eligible adults? Let's wait & see how the group of trials of these vaxes stack up. But it will be effectiveness that matters in the end, not just potential efficacy. /8
...PS: cut-and-paste fail - here's the right attached tweet on Serrana (tweet 7 🧶 above)

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More from @hildabast

11 Apr
Preprint on Brazilian trial by @butantanoficial of Sinovac's CoronaVac, 2 weeks apart. Data for 9,823 people who had 2 doses, 12,396 after 1 dose.The P1 ("Brazilian") variant of concern was not circulating in the areas the trial ran...1/n papers.ssrn.com/sol3/papers.cf… HT @josegallucci
...14-day interval seems too close, & immunity may increase over time: they recommend 28 days. Their primary efficacy, unlike other vax trials, includes people who had previous SARS-CoV-2 infection. But this table provides the comparable number: 50.5% (CI 34-63)..2/n
...Their primary efficacy analysis was based on 85 vs 168 people with symptomatic Covid-19. Unfortunately, they don't provide detailed data on symptoms so can't try to see whether this was milder disease than other trials... 3/n
Read 10 tweets
10 Apr
The FDA has said it investigated the blood clot/low platelets cases after J&J vaccine & found no causal association with the vaccine: they're continuing to investigate. abc.net.au/news/2021-04-1… Given the way the EMA's statement of formal investigation is being reported,...1/4
..I went back to EMA press conference to check my tweets. Peter Arlett from EMA said: (at ~40 mins) Since the trial "There have been 3 cases with the J&J vaccine of blood clots associated with low platelets which have some similarities to these cases...2/4
...that we’ve been describing today for AstraZeneca vaccine. However the numbers are extremely small compared to the 4.5 million patients vaccinees that have received the J&J vaccine worldwide.” (~51 mins) "…if you look at those reports of blood clots with thrombocytopenia...3/4
Read 4 tweets
8 Apr
Digging into the detailed EMA report on the AZ vaccine investigation. (The committee vote for their decision was 31 out of 32.) They discuss several hypotheses that have been proposed for the phenomenon, if it's triggered by the vaccine.
ema.europa.eu/en/documents/p…
...1/n
..1st was one from researchers in Germany/Austria, based on studying several of the people: that it's similar to heparin-induced thrombocytopenia ("HITT-like"), & related to Platelet Factor 4. assets.researchsquare.com/files/rs-36235… (preprint)...2/n
...EMA conclusion: there are similarities, so still needs to be investigated. But there are differences too: eg HITT doesn't cause a condition that occurred here (DIC). So they called this unproven...3/n
Read 11 tweets
7 Apr
EMA is listing unusual blood clots with low platelets as a side effect of the AstraZeneca Covid vaccine ema.europa.eu/en/news/astraz… 1/n
...90 cases: 62 with CVST & 24 with splanchnic vein thrombosis (that's abdominal). 18 of 90 people died. It was 90 out 25m, so less than 4 per million. An immune response is a plausible explanation for this, they conclude. 2/n
...MHRA's press conference is delayed, so no word yet there... 3/n
Read 23 tweets
22 Mar
Oh this is great news! 🥳

Oxford-AstraZeneca vaccine: 79% efficacy & possibly increasing over time

Press release for interim efficacy results from the US trial for 32,449 people, randomized 2:1 to placebo (140 events - symptomatic Covid-19)... 1/n

astrazeneca.com/content/astraz…
... Typo in previous tweet: 141 events. (No confidence intervals provided.)

....2/n
...Vaccine efficacy was consistent across ethnicity & age, include older. It was 80% for people aged 65 & older.

No breakdown of events by vaccine & placebo...3/n
Read 8 tweets
22 Mar
Distracted by the other EMA thing, I'm only just catching up with the 218-page EMA assessment report for the J&J vaccine ema.europa.eu/en/documents/a…

For background, my summary from the 62-page FDA report is here absolutelymaybe.plos.org/2021/03/16/com…

Tweeting about what's new or different...1/n
...As usual, in-depth look at quality of manufacturing. "No raw materials of human or animal origin are used" in the final production. The cell line used to optimise production of the vaccine vector is PER.C6, which has already been studied for safety...2/n
...Current batches manufactured mostly in Leiden & emerging in Baltimore: they've shown consistency in the European manufacture - EMA wants them to follow-up with data showing the Baltimore production is comparable (this is all standard) ...3/n
Read 19 tweets

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