Thread by @WesPegden, There's been a lot of controversy surrounding vaccine prioritization. There are various [...]

There's been a lot of controversy surrounding vaccine prioritization. There are various sides to this issue and it's easy for them to get conflated in a way which confuses the conversation. Quick thread. 1/13

First: it is of course true that vaccine programs can have different goals. Minimizing deaths and serious illness by direct protection via vaccine is a different goal from attempting to reduce onward transmission (and then deaths) by vaccinating highly exposed individuals. 2/13

And even as part of a direct protection strategy, some individuals might really have 10x the exposure risk of others, so it is not a priori unreasonable to consider exposure risk even if the primary strategy is direct protection.
3/13

However:

what IS unreasonable is mistaking the real but moderate role of various common "risk factors" for serious and illness and death from COVID with the overwhelming, multiple-orders-of-magnitude effect of advanced age. 4/13

For example, in this figure from the large NHS risk study, the relative risk for 18-39 year olds is so low that it doesn't fit on the chosen log scale.

Common conditions such as diabetes and obesity are not nearly as relevant as age. 5/13

In the U.S., each of the 50 states is pursuing their own vaccine plan. In PA's plan, for example, a person of any age with "high risk conditions" such as BMI>=30 or "smoking" are given higher priority than 60-year olds.

It isn't enough for the CDC to know what the CDC means.

Currently there is a tendency in plans to
*) overestimate the relevance of common non-age risk factors
*) fail to differentiate the effects of advanced below age 65.

A 60-year old faces something like 30x the risk of death as a 30-year old from COVID; plans should reflect this.

I have seen various explanations offered for the current state of things.

One is that the vaccine simply works better among older populations than was expected; in particular that we should soon see recommendations updated. 8/13

However, the biggest contradictions is plans right now is not how they deal with the oldest people but how they deal with people under 65, but for whom age is still their greatest risk factor.

Good plans should differentiate 55-65, 45-55, 35-45, etc.

9/13

Another explanation is that exposure considerations may be at play. But the primary issue at hand is not plans which prioritize people because of their exposure but because they have medical risk factors (weight, smoking, etc), which are real but minor compared with age. 10/13

I have also seen explanations suggesting that "logistics" are the reason.

To me it seems this misunderstands the urgency and consequence of getting the first doses of the vaccine to individuals where it is most likely to have the greatest impact. 11/13

As age has an orders-of-magnitude effect, a plan which prioritizes age can be more effective even than a plan which was less targeted but distributed 2x as many doses. For all the advocacy around using single doses, etc., giving the doses to the right people matters the most.
12/

Finally I have seen it suggested that this is just the temporary state of things and it is all going to get worked out in time.

This is the one I hope is right!

But the states are already writing their plans. It's not enough for the final CDC plan to get it right.

13/13

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