Post #1069: What is the limit to COVID-19 vaccination for the elderly?

Posted on March 22, 2021

I’ve been trying to find time-series data on COVID-19 vaccinations by age.  The idea being to determine whether or not we’re reaching saturation within the elderly population.  That is, the point where no more elderly individuals choose to be vaccinated against COVID-19.

Nationally, all I can get is the occasional screen shot.  Like so:

Doing the math, that turns out to be 0.8 percentage points per day increase, for the past three days, for the U.S.  That compares to a 1.2 percentage points per day increase in the three weeks leading up to 3/18/2021 (Post #1064).

For Virginia, it looks like this, with 3/22/2021 on the top, and 3/19/2021 on the bottom:

That works out to be 1.1 percentage points per day for the 70-79 group, and 0.8 percentage points per day for the 80+ group.  That’s actually faster than the 0.7 percentage points per day in the two weeks leading up to 3/19/2021 (Post #1064).

The upshot of that is that we haven’t reached that limit yet.  Though whether we are close, or whether its even slowing down, I can’t tell from the available data.

North Dakota

A reader sent me a link to relevant data from North Dakota (below), which at least shows a graph of vaccinate rates by age over time.   (I have removed the last week of data, which merely duplicates the next-to-last week in this graph.)  Let me run with that, because I don’t seem to be finding much else showing vaccination rates by age over time.

There, it looks fairly clear that they’re reaching the saturation point among their elderly, and that the saturation point for all elderly combined in North Dakota may be something less than 70%.

North Dakota is well ahead of the U.S. in terms of the progress of its vaccination program, but somewhat below the U.S. average in terms of COVID-19 vaccine acceptance.

Source:  New York Times, accessed 3/22/2021.

As of today, North Dakota is the 6th-ranked U.S. state in terms of total fraction of the population vaccinated.  So this is probably a pretty good estimate of where the North Dakota elderly will end up.

Source:  Carnegie-Mellon University Covid Delphi Project, accessed 3/22/2021.

However, North Dakota is about four percentage points below the median for self-reported vaccine acceptance.  So if you wanted to guess the ultimate overall U.S. vaccine acceptance rate for the elderly, at first blush, you’d add 4 percentage points to what you’re seeing in North Dakota.

Other states

Here are a few other states, chosen because they have a lot of their population vaccinated and they are near-average in terms of vaccine acceptance.  This is a sample of convenience, because some states do not report this information in a usable form.  Finally, some states do not include counts from Federal programs specifically targeting (e.g.) nursing home residents.

Alaska: By calculation, 66.8% of the age 70-79 population of Alaska has been vaccinated.  That’s from vaccination counts from the State of Alaska, and 2020 population estimates from U.S. Census.  That’s a good fix because a) Alaska is well along on its vaccinations, b) Alaska has vaccine acceptance rates that match the U.S. average, and c) Alaska has opened up vaccination to everybody over age 16.  Hence, best guess, that 66.8% is pretty much all they expect to get.

New Mexico:  This is another state that is well along in vaccination, and has just slightly-above average vaccine acceptance.  New Mexico has vaccinated just over 68% of their age 75+ population.

Source:  New Mexico Department of Health.

Maine:  By calculation based on Maine Department of Health counts, Maine has vaccinated 80.5% of their age 70-79 population.  But Maine appears only slightly above average in terms of COVID-19 vaccine acceptance.

At this point, I doubt I’m going to learn much more.  The vaccinated fraction of the elderly seems to cluster just below the 70% mark, but you can find exceptions (like Maine) where a much higher fraction has been vaccinated.

The only hard information is that the fraction of the elderly who have been COVID-19 vaccinated continues to increase.  There’s no strong evidence yet that the rate of increase is tapering off for the U.S. as a whole.  There is strong evidence that it has tapered off in selected states (e.g., North Dakota).

With the state-reported data, we have the additional uncertainty as to whether or not their numbers include Federal programs to vaccinate those in nursing homes and to distribute vaccines through commercial pharmacies.

At this point, I think the only viable option is to keep watching the CDC-reported data.  Presumably, they have the information to allow them to count all vaccinations, including those through the Federal programs.  My plan is to take a screenshot of the CDC counts every week or so to track this.  You’d think there’d be an easier and more systematic way to do it.  But as far as I can tell, that’s not true.