Nailed It: Palm Beach Post confirms my suspicions re. Miami-Dade County (& Florida in general)

Back in early September I wrote about something which had been bothering me for awhile:

As you might expect, there's a clear drop-off in new COVID cases per capita as the vaccination rate of the counties goes up. There seems to bea slight drop-off starting around 50% fully vaccinated, followed by a steep drop-off starting around 65% vaxxed.

There's a third drop-off at around 75%, but there's literally only a handful of counties which have achieved that high a vaccination rate so far anyway.

HOWEVER, there's one major outlier over the 65% threshold...Miami-Dade County.

According to the Centers for Disease Control, Miami-Dade has fully vaccinated 68% of their entire population (1.84 million out of 2.72 million residents). I use the slightly lower official 2020 U.S. Census popualtion count for Miami-Dade County (2,701,767), which makes the vaccination rate slightly higher still: 68.24%.

And yet, somehow the 10th-largest county in the United States, which has the 6th highest vaccination rate of any county over 1 million residents, also has the highest new case rate of any county over 1 million residents.

At the time, it was Miami-Dade's massive outlier status in terms of COVID cases since the beginning of July which had tipped me off; it looked like this:

After putting this out as an open question to anyone from Florida who had some insight, a two common themes kept coming as reasions for the discrepancy:

...the most common thinking is that it's a combination of lots of snowbirds (seniors who live up north and only spend the winter in Miami-Dade) who got vaccinated in M-D back in January/February before flying back up north for the rest of the year) and "Medical Tourism"...i.e., folks from other countries flying into M-D, getting vaccinated and then flying back to their home country.

I followed up on this in November, including breaking out county-level death rates by vaccination rate in bar graph format, showing what it would look like if you removed Miami-Dade County from the equation altogether. In short, the death rate in the least-vaccinated decile fo the U.S. went from being ~4.4x higher than the most-vaccinated decile to a whopping ~6.3x higher if Miami-Dade wasn't included in the most-vaxxed decile at all:

This was in November, before the Omicron variant wave, of course, so it'll look somewhat different today (I'll have an updated version of this graph tomorrow), but the point stands.

Well, a few days ago Palm Beach Post reporter Chris Persaud (w/help from David Berman) published an in-depth analysis of Florida's questionable vaccination rate data and sure enough...

Florida overcounts vaccinations by 600,000 people. Snowbirds responsible, analysis shows.

• Health officials and Gov. Ron DeSantis say they have no plan to fix this statistical flaw, driven by out-of-staters.

...More than 100 Florida ZIP codes each report that more than 100% of their residents have gotten at least one coronavirus vaccine shot. In some cases, the number of vaccine recipients recorded by the state Health Department exceeded U.S. Census population estimates by more than 1,000%.

These ZIP codes — popular among seasonal residents and tourists — together counted about 622,000 more inoculations than people living there year-round.

That comprises 4% of vaccine recipients tracked by a database state health officials gave on Wednesday to lawyers representing a consortium of news outlets, including The Palm Beach Post.

About 74% of eligible "residents" ages 5 and older are at least partially inoculated, state health officials reported March 11. And about 24% have received a booster shot. The overcounted inoculations are equivalent to about 3% of vaccine-eligible Floridians.

...Florida's official data also underestimates how many residents have never been vaccinated, Salemi said.

...Florida reported a total of more than 5.8 million infections and 71,860 deaths as of March 11. But those numbers exclude tourists, snowbirds and other visitors who caught the virus here.

...Nearly 2.3 million immunized people across Florida listed their residences in ZIP codes with impossible vaccination rates, according to the state Health Department database.

But fewer than 1.7 million vaccine-eligible people live in these places for more than half the year, Census surveys conducted from 2016 to 2020 found. ZIP code-level estimates for 2021 are not yet publicly available.

Florida’s growth since 2020 does not fully explain the six-figure discrepancy between immunizations and estimated population in ZIP codes analyzed. Much of it is driven by out-of-state residents who stay here during winter.

...Much of the impossible immunization rates in Miami-Dade County can be explained by “international people who give a local address just to get the vaccine,” Alonso said. “We have vaccinated almost all of Colombia. That's one of the jokes.”

Whle my own analysis from last September used case rates and the analysis by the Palm Beach Post uses "at least one dose" as their comparison basis, here's what national county-level death rates look like since May 1st, 2021 when broken out by the official 2-dose vaccination rate as reported to the CDC by the Florida health department, as of yesterday:

While there are several outliers at both ends, the two most blatant ones on the high side are both from Florida: Miami-Dade County, along with Sumter County, although Sumter has a very different explanation: It's home to The Villages, the Trump-loving retirement community which comprises over 60% of the total population.

Sumter may be heavily vaccinated, but when you combine nearly 82% of the population being over 65 with that massive Trump support, it's not terribly surprising that they're still facing a high death rate.

As an aside: While some of this sort of data fuzziness due to non-residents can be found in other states/counties as well, it appears to be far, far higher in Florida (and especially in Miami-Dade County specifically):

...California, the most populous state, reported about 471,000 vaccine recipients in the wrong ZIP codes as of Tuesday, about 25% less than what The Post found in Florida.

Those excess shots in California represent about 1.5% of all immunizations there, about one-third of Florida’s level.

The rate is similar in Arizona, another popular state for winter tourists, with 1.4%. (Arizona does not yet report data for tribal areas).

Arizona and California regularly release ZIP code-level vaccination data to the public and keeps it updated. Florida does not.

UPDATE: While the full 100+ zip codes referenced in the Palm Beach Post story aren't easily available (you have to roll over each individual zip code on the interactive map), I've managed to match up 23 of them within Miami-Dade County which contain over 331,000 of the ~622,000 "phantom resident" vaccinations referred to, or over 53% of the total state-wide.

Of course, the actual number is likely considerably higher than 622,000...those are just the ones which surpass 100% of the resident populations of those zip codes. There are likely several hundred thousand more in zip codes where the official count is, say, 98% when it should actually be 75% or whatever...but there's no way of being certain about those.

What this does mean is that in Miami-Dade County, at least, the actual 2-dose vaccination total is only 1,955,746 residents (72.4% of the total population) at most instead of the official count of 2,287,381 (84.7%). That's a drop of 12.3 points.

Assuming the actual vaccination rate for M-D is ~72%, it would be where the big black circle below is: