Thread by @adam_t_clark

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

https://twitter.com/adam_t_clark/status/1360652271210618890

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

https://twitter.com/sailorrooscout/status/1359946547887243265

Additionally, there's been all sorts of good news on vaccine efficacy this week, including a study in Scotland showing very high protection against severe COVID from both the AZ and mRNA vaccines (albeit in a region without B.1.351)... 4/n

https://twitter.com/sailorrooscout/status/1363898240857497604

and another larger study from Oxford suggesting both higher AZ efficacy given longer dosing intervals, and, read optimistically, that the vaccine might prevent >50% of transmission events (though again, without data RE B.1.351). 5/n
papers.ssrn.com/sol3/papers.cf…

The upshot is that no matter what, it is clearly critical for EU public health that all available AZ doses be used ASAP - even if B.1.351 spreads, and even if it turns out that AZ protection against severe cases is much lower than for other vaccines. 6/n

But, here's the problem: lots of people in the EU don't want it. It's hard to separate real stories from the social media chaff, but at least here in Austria, a fair number of physicians groups are refusing to be vaccinated with AZ. 7/n
salzburg.orf.at/stories/308863…

I'm worried that without major interventions, the problem will get much worse. Nobody wants leftover vaccine that the physicians rejected. And I don't think that existing efforts ("It's just as effective as other vaccines in most cases") are working. 8/n

https://twitter.com/BMG_Bund/status/1363837256528723969

The issue is that all vaccines are not equally effective. All appear to work great at preventing death/serious illness, but the mRNAs provide better protection against mild/moderate COVID, probably prevent transmission better, and might work better against the new variants. 9/n

And the reality is that we don't have enough doses of anything - so people who get AZ are foregoing other vaccines for the foreseeable future. So, how we can get people to make a decision that is beneficial to the public, but a potential opportunity cost to themselves? 10/n

If there is one thing that we have learned from other science-based policy interventions, the answer is never to lie or gaslight. This erodes public trust, and almost always backfires. I think we need to be transparent that some people are getting a worse shake than others. 11/n

So what to do? One option would be to force everyone to get vaccinated - but that seems unlikely in the EU. Another would be to punish people who refuse AZ, but that also seems unlikely, since the whole goal is to get as many people vaccinated as possible. 12/n

Another option is to let people choose, but to make it slow and annoying. That seems to be the option being used in Salzburg, where physicians who refuse AZ do not lose their vaccination priority status, but will need to wait for alternatives. 13/n
salzburg.orf.at/stories/309104…

But, the "slow and annoying" strategy only works so long as there are enough other people left who are willing to take AZ. So far, that seems to have been the case, though there are mounting stories of vaccination centres with large numbers of unused doses. 14/n

I can see these numbers getting even higher as we move on to vaccinating younger and healthier people, who are less worried about severe cases, and more worried about being left waiting at the back of the line again for boosters in the coming years. 15/n

In that case, I think the EU will need to guarantee that if AZ turns out to be ineffective against new strains, then recipients will be given precedence for boosters, potentially even at the expense of unvaccinated people. If poor AZ efficacy is unlikely, so much the better. 16/n

Alternatively, they could appeal to social responsibility, and remind people that the faster we vaccinate, the faster we exit the crisis. I know it sounds sappy, but remember that similar logic has been getting young people to (mostly) adhere to lockdowns for the last year. 17/n

But whatever happens, I think that the EU, and individual governments, desperately need to change tack, and fast. A large fraction of vaccine deliveries will be coming from AZ for the foreseeable future, and we need to find candid, honest ways to get people to accept them. 18/18.