I was disappointed by the news conference today from the EMA regarding #AstraZeneca. The upshot is that AZ has been tied to rare cerebral thrombosis, but EMA still believes that benefits outweigh the costs (on average). 1/n ema.europa.eu/en/news/astraz…
But, I am worried that we are going to have to eventually pay back the balance on three issues that have been largely pushed under the rug, but risk undermining public trust and slowing down vaccination campaigns in the the EU and worldwide: efficacy, risk, and side effects. 2/n
Regarding efficacy: among vaccines approved in the EU, AZ is the least effective at preventing mild to moderate COVID, especially with respect to variants (though there is reason to believe that efficacy against severe cases/death is still high). 3/n
Regarding risk: although getting COVID is bad news for anyone, there is a strong drop-off in risk with age, with significantly higher risk for men than for women. And so a young woman is orders of magnitude less likely to die of COVID than an old man. 4/n statistik.at/web_de/presse/….
Finally, regarding side-effects, although data are still preliminary, it seems clear that risks of severe side effects from AZ follow the opposite trend as COVID, with higher risks for young people and for women. 5/n
All three of these factors are only going to become more apparent with time: so far, we have enough data to know that significant differences in efficacy, risk, and side effects exist, but not really enough to quantify those differences. But, soon we will. 6/n
For young people, and especially young women, these factors seem likely to align and make it reasonable and rational to refuse AZ, and hold out for a different vaccine. The UK has already acted on this and decided to offer under 30's alternate vaccines.
bbc.com/news/world-eur…
And so, in a few months, the idea that "all vaccines are safe and effective", or "the best vaccine is the first one you are offered" is going to be a lot harder to sell, and the public is going to be very confused, and potentially angry, about having been told otherwise. 8/n
I get that it is vital for public health and economic recovery that as many people as possible are vaccinated as quickly as possible. And I desperately want to get vaccinated when my turn comes. So, please don't @ me. 9/n
But, I worry that we will find that we are trading in our credibility in order to get a small gain in vaccination rates today, in exchange for an overall loss of trust from the public tomorrow, which will hurt our response to COVID, and to future pandemics. 10/n
I think we need to be brutally honest with people about the costs and benefits of various vaccines for different groups of people. And, where public health goals don't align with individual incentives, we need to find viable counter-incentives (alternate vaccines, $, etc.). 11/11

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More from @adam_t_clark

22 Feb
I don't was to get too far from my tree, but there's a growing issue at the stats/policy boundary regarding #AstraZeneka and #B1351 that I wish was getting more series coverage. The EU needs lots of people (20-30%?) to agree to be vaccinated with AZ, but many don't want to. 1/n
Reasons include lots of things that aren't well supported by data (e.g. "higher side-effects", "slower efficacy"), but also some that are, especially regarding very low efficacy against mild to moderate cases of the B.1.351 "South African" variant. 2/n
Nevertheless, people who know a lot more about immune responses than I do seem to be relatively sure that the AZ vaccine will protect against severe COVID cases, hospitalisation, and death, even for the B.1.351 variant. 3/n
Read 18 tweets
13 Feb
There's been a lot of media buzz around the efficacy of the AstraZeneca vaccine against the B.1.351 COVID-19 Variant first identified in South Africa. In particular, a recent study by @ShabirMadh et al. suggests it could be very low, at least for mild to moderate cases. 1/25
I've seen lots of people suggest that the sample sizes in the study are "too low" to say anything definitive - but, this is actually a pretty good opportunity for a power analysis. Since I haven't seen much discussion of the study's power, I thought I would post one here. 2/25
First, a few caveats. The study is available here: medrxiv.org/content/10.110…. This is a pre-print, and so results are not yet peer-reviewed, could potentially be subject to change. 3/25
Read 26 tweets

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