have been too cautious, so afraid of the consequences of getting a decision wrong that they've cost lives through inaction and delay. This is *very* relevant to the J&J issue. Thread I fall on the side that thinks they are too cautious. I think that's clear. But it's a mistake to think these are easy decisions, or to just say that the math is 6 blood clots out of 6.5 million shots, so wtf are you thinking. That's missing their actual fears. Mass vaccination campaigns work only if the masses take the vaccines. As Daniel Carpenter said to me, “In this way, it’s a deeply social technology, and so the credibility is everything.” "Effective therapies depend on credible regulation." FDA is worried they missed something on J&J, and if it gets worse, and the public blames them for rushing the vaccine, that trust could collapse in *all* the vaccines, and in future vaccines. The cost of that would be incalculable. Expert vaccine Twitter is a risk tolerant place, full of people who work backwards from the appendices in pre-prints to come up with their sense of acceptable risk. In this hothouse, the danger is always doing too little. Public psychology is less data-driven. But here's the counterargument: There's no actual evidence the FDA knows how to manage public psychology correctly on this. Would it be better to report the data, be honest about the risks, and tell people to make the decision that's best for them? Maybe! Is it possible that the FDA is going to increase vaccine hesitancy here, rather than lower it? Definitely. Let's say, in three days, they clear J&J totally. Will that get the news coverage the pause did? Will it fully end the fears the public now has? I doubt it. The UK offers another path: They've gone to first doses first, approved Oxford-AstraZeneca (though have gotten worried about clotting issues there, too!), tried human challenge trials. Is vaccine hesitancy higher there? No, it's lower. On the merits, I think the FDA's skeptics are right. There are something like 6 clotting events (that we know of) out of 6.5 million shots. The danger is small and theoretical. Meanwhile, the B117 strain is spreading across the country. The danger is huge and real. If you're going to pause J&J, go to first doses first of Pfizer and Moderna. Or since the clots were all in women, use J&J for men, and Pfizer/Moderna for women. Do something to show you are as fearful of B117 as adverse vaccine events. This is my ultimate criticism of the regulators in this. I take their fears seriously. Their job is very hard. But they are not being creative in balancing these risks, and that means they're running too much coronavirus risk. And they may be *increasing* vaccine fears. In a statement, the FDA said “We are recommending a pause in the use of this vaccine out of an abundance of caution." What does an abundance of caution on B117 demand? How about an abundance of caution for those who need a vaccine and can't get one? One place my beliefs have shifted during the pandemic: I think regulators, broadly, are too afraid of trusting the public with information and letting us weigh risks. That doesn't work on everything. You need good information to make good decisions. I'm not someone who thinks you should be able to take any medication by signing a release waiver. Too many people are out there trying to actively fool the sick, the dying, the scared. But we've given 6.5m shots of J&J (including to me!). There were 6 clotting events, all women between 18 and 48. There's a lot of data here. There were options between a screeching halt to J&J and doing nothing. Options in which the public could've been brought in as a partner. 💡Reposted from Twitter. The thread included the following link: