1. My semi-informed opinion is that it's a good thing ACIP changed its mind, and gave older adults higher priority for getting the Covid vaccine.

But my informed opinion is that the way ACIP made this decision was, in the most banal sense, not good. https://www.statnews.com/2020/12/20/adults-over-75-frontline-essential-workers-should-be-in-second-covid-19-vaccine-priority-group-says-cdc-advisory-panel/

2. The decision about who should get vaccinated first is not an easy one. While vaccinating the elderly first (after health-care workers) would, according to ACIP's own models, save more lives, that isn't necessarily the only consideration when it comes to vaccine distribution.

3. Some might argue that curbing transmission (which would probably lead you to vaccinate people who have to interact with others) is more important. Others think what public-health people call "health equity" is important to take into account.

4. Then there are younger people who are high-risk because of underlying medical conditions - where should they go on the list?

The point is that even if you think, as I do, that vaccinating the elderly first makes the most sense, it's not a no-brainer.

5. The problem, though, is that until they changed their minds, the ACIP panelists actually did treat it as a no-brainer - except in the opposite direction. At their November meeting, all 14 panelists supported vaccinating essential workers ahead of almost all the elderly.

6. Now, I don't know anything about the science of vaccines. But I know a lot about group decision-making and small-group dynamics. And if a group of 14 people trying to solve a challenging, complex problem all agree on the solution, that's a sign the group is not working well.

7. Groups are most likely to reach good decisions when they're made up of cognitively diverse individuals who are willing to disagree with each other. Unanimity about an answer to a complex question suggests the group is too homogeneous in its outlook.

8. Again, I'm not downplaying the complexity of the problem ACIP had to solve. Instead, I'm saying that given how complex the problem was, and the difficult trade-offs any solution would require, it was improbable, and unhealthy, that every panelist came up with the same answer.

9. In fact, if you listen to that Nov. meeting (which I recommend), it's striking how little substantive disagreement is voiced, and how little discussion there was of the fundamental trade-off the panelists were, at that point, willing to make.

10. If you supported the proposal to vaccinate essential workers ahead of most of the elderly you were, in effect, saying that considerations like health equity and helping keep society and the economy working were worth having more people die of Covid than otherwise would have.

11. That's actually a defensible position. Maximizing lives saved is not the only objective of policy, even public-health policy. If it were, we would have 25 mph speed limits on the highway, and we would have shut down everything in March, instead of keeping so much open.

12. But even if it's a defensible position, it's not inarguably true. So it's just very odd that none of the panelists opposed it. And it's odd that, in that Nov. meeting, there was little discussion of the fact that the proposed plan meant that more old people would die.

13. What makes the absence of opposition to that plan especially weird, of course, is that yesterday, less than a month after the Nov. meeting, the panelists reversed themselves, voting 13-1 to move a big chunk of the elderly up in the queue.

14. Now, certain things have changed since Nov.: we have more info about the effectiveness of the vaccine in the elderly. But the fundamental math isn't any different: ACIP's own models said that vaccinating the elderly first would save lives.

15. If everyone in a group thinks one thing in November and just about everyone in that group thinks the opposite a month later, that doesn't mean the people in that group are open-minded. It means they were too homogeneous in their thinking to begin with.

16. So what should change? First, I think it makes sense to have decisions about vaccine prioritization be made by groups with members with a more diverse set of backgrounds, including non-public-health backgrounds.

17. Second, and perhaps more important, any such group should not strive for unanimity, especially not before the final vote is taken. It should welcome disagreement, and encourage public discussion of even the most difficult trade-offs vaccine prioritization can require.

18. The nature of hard problems is that informed people of good faith disagree about what the right answer is. So groups that make good decisions are built to foster a diversity of opinions, and lean into that disagreement, rather than shying from it. /FIN