Delta Surge Update – Demographics Focus 8/13/21

Hospitalization (Arizona)

One question that hasn’t been well addressed in the media (all political bents) is whether the COVID Delta surge was driving hospitalization and who, indeed, was being hospitalized. My thinking is that this is our prime metric of the danger of a COVID surge these days. Here’s a chart showing the Arizona hospitalization numbers by demographic. It’s a bit messy for a couple of reasons: 1) Arizona keeps “catching up” on hospitalization numbers by dumping large count backlogs into a single day. I suspect this is a hard metric to keep up with due to all the hospital systems in the state and their state of enthusiasm (?) about reporting data… 2) I stopped capturing the daily snapshot from AZDHS’ web site sometime in May when the data got really boring and moved to weekly (or so). This means my trends aren’t as granular as before, but they’re still accurate.

Arizona Hospitalization (beds used) Data by Age – AZDHS data, collected by T.N. – 8/13/21

What do we see above? Note that at the left of the chart, the hospitalization by age is fairly random and driven by low numbers and statistics. However, if you can ignore the glitch in the middle, the trend is pretty clear towards the right (the Delta Surge). Hospitalization numbers are clearly trending up (but are still not significantly higher than in May. What does this trend reveal? Surprisingly, the over65 age group is still getting hospitalized at much higher rates than their percentage of the population would indicate. No way to know if these are vaccinated people or not. That’s a big gap in the data. They’re matched in numbers by the much-larger 20-44 age group and followed closely by the 45-54 and 55-64 groups. The under 20 age group remains the least hospitalized. This seems to go against some of the news reports that are indicating that the Delta variant is having more severe outcomes in the youngest cases. That doesn’t seem to be the case right now in Arizona at least.

Below I’m showing the hospitalization numbers for all age demographics. As you can see, the Delta surge (furthest right) has not been surging in the hospitals the same way the earlier two surges did. Keep your eye on this chart as things move forward.

AZ Hospitalization since 4/20 (https://www.azdhs.gov/covid19/data/index.php#hospitalization)

Cases – Pima County

In my county (Pima) the Delta surge has resulted in proportionately less cases than in the much-larger Maricopa County. My suspicion is that this is due to the notably higher vaccination rates in Pima County. But again, the big question is which demographics are getting infected during the current surge?

Pima County Cases by Age Demographic – 8/13/21

Again, ignoring the loss of granularity by my moving to weekly data capture, you can see the trending on cases from the lows of May until now. It’s no surprise that the 20-44 age group is leading the case counts. In general, across Arizona, this group is much less likely than older demographics to get vaccinated. Plus, there’s more of them. However, the most interesting part of this chart is that the under 20 group is the next highest increase in cases. This group is largely unvaccinated, but it’s not clear how many of them are between 12 and 20 and how many are under 12. This is an error in data collection “strategy” that’s been a problem throughout COVID. Perhaps no one expected at the start that the under 16 demographic (school age) would be so interesting for this pandemic. The rest of the demographics (more vaccination and older) are barely seeing any case rate uptick since May. So, again, fairly surprising that the youngest demographics are the primary ones getting the Delta variant of COVID. No doubt “breakthrough” cases are happening in vaccinated people, but perhaps they’re not symptomatic enough to get counted. Or maybe there are just very few of them (despite what the headlines would indicate).

I just show Pima County here, but statewide, the trend is similar. At the state level, the case rates in the older demographics are slightly higher than Pima county and the younger demographic case rates are noticeably higher. This, again, is driven by the much higher rates and lower vaccination in huge Maricopa County.

Deaths

There isn’t much change to death rates during the Delta surge from the low period of May. Deaths are still very low, as you can see from the height of the stacked blue and red bars in the chart below. The only thing that *might* be interesting is that the ratio of deaths in the over65 demographic to deaths in every other demographic is much lower now. Sometimes we see this when deaths are low, but during the two previous surges, this ratio trended between 2.5 and 4. Right now it ranges around 2 or lower. This ratio is the green line in the chart below (and the red bars are “over65” deaths and blue bars are “under65” deaths). What might this mean? Again, I suspect it is the power of the vaccine to limit deaths in the over 65 community. I keep tracking this number and I hope that it doesn’t trend up again.

COVID Case Rates in heavy- and low-vaccinated States – 8/5/21

This may not be surprising at all, but the states with the lowest rates of vaccination are seeing case accelerations but the states with the highest rates of vaccinations are only seeing linear case rates. See below.

States with Lowest Vaccination Rates (as of 8/5/21)
States with Highest Vaccination Rates (as of 8/5/21)

I’m not sure what to make of the interesting spread in cases per 1000 across the 8 highest vaccinated states. Perhaps this makes the case that different approaches to state intervention yielded different results. New Mexico, for instance, had some of the more disruptive lockdowns and you can see that they flattened out earlier than New Jersey or Washington. But regardless, you’ll note that only a couple of these states have any case rate increase at all right now. However, the top chart shows states that have tended towards less government intervention and perhaps this is the reason their vaccination rates are low.

By County in AZ

I also see this result by county in Arizona. The highest vaccinated counties are all near the border (Yuma, Pima, Santa Cruz, Cochise) or near large Native reservations (Apache, Navajo, Coconino).

You’ll notice on the table and map below that these counties all have the lowest case rates and accelerations. In the map, the warmer colors represent higher case growth rates and the bubble diameter represents Zip code population. This shows the higher case rates are all in the counties with lower vaccination rates.

AZ State Data Table – 8/5/21
Arizona Zip Code COVID growth since April 2021.

Death Rates

I’m not including any slides on the death rates. They’re still low across the board compared with earlier outbreaks, but the states with lower vaccination rates do have slightly higher slopes, it seems.

Hospitalization (ICU beds)

# of ICU beds in use by COVID patients – 8/5/21 (https://www.azdhs.gov/covid19/data/index.php#specific-metrics)

It’s hard to know what’s going on with the ICU bed usage rates… You may notice that for about a week the numbers have plateaued. This could be a data collection issue, or it could be that the hospitalization rate for ICU beds has slowed. I have noticed that COVID discharge rates seem very strong, so this might be a testament to hospitals improvements in treating serious COVID cases. I continue to track this metric.

Update on the Delta variant Surge – 7/31/21

As always, I’m capturing the state of the COVID pandemic through data. See below for the latest data across the US on the “Delta Surge”.

Current US State Status

State Data Table – 7/31/21

Above is the standard Data Table that I build from the Johns Hopkins COVID data. You might note that the Case Rates (IROC_confirmed) and Case Accelerations (dIROC_confirmed) are increased over the previous two posts here and here. The rate that Lousiana’s case rate is increasing is surprisingly high… perhaps the highest acceleration I’ve seen yet for a whole state. This may be another data point demonstrating how quickly this delta variant spreads.

Hot Spot Counties

Hotspot County Data Table – 7/31
Hotspot County Map – 7/31/21

Above we can see a number of interesting things about the current Delta outbreak. First, the Louisiana Parishes at the top have really high rates and accelerations. This is one of the big reasons the whole state of Louisiana is surging. The top three parishes are all medium sized parishes that sit in between Baton Rouge and the New Orleans area, so perhaps their outbreaks are related.

The case rates and accelerations continue to inch upwards in the previous hotspot areas (Missouri/Arkansas border and Jacksonville, FL, area) but they’re not racing up anywhere near as quickly as Louisiana.

Finally, despite all these new cases, death rates are still extremely low… about 5 to 10 times lower rates of deaths per 1000 persons per day than back in January during the winter outbreak. For instance, Apache County, AZ, had the highest case rate in the state at this time (.728) but had a death rate of .033. Compare to any of the counties in the table above. They all have higher case rates than Apache County during January of 2021 and the highest death rate I see is .0082 in Phelps County, MO.

All I can take away from this is that 1) the Delta Variant is less deadly than the variant spreading in January, 2) our medical system has gotten much better at treating COVID, or 3) the deaths are lagging and we’ll start to see them showing up later. Of course we have the variable of vaccinations present now which could be impacting 1) above by making the virus less deadly in a society of a mix of vaccinated and unvaccinated victims.

Hospitalization Status in AZ due to COVID

ICU Hospital Bed Capacity (https://www.azdhs.gov/covid19/data/#hospital-bed-usage) – 7/31/21

Above is the current status from the state of Arizona of hospital beds. The Arizona case numbers are creeping up but are still relatively low (see below). Hospitalization (ICU) due to COVID is increasing, but it hasn’t yet hit the rates that were seen even in April of 2020. The trend here will be a good indicator of how serious this Delta outbreak is.

Arizona State Data Table – 7/31/21

Delta Variant Updates – US States – 7/24/21

Here are the latest updates for those of you who want to see the data.

COVID by State

State Data Table sorted by Case Rate – 7/24/21

The most interesting thing to note from above is that the acceleration column (dIROC_confirmed) is getting larger in the top 15-20 states ranked by their Case Rates (IROC_confirmed). See my post from July 15 to see the difference. You’ll also note that the case rate is increasing pretty much across the board, but for most of the lower-ranked states, it’s a small increase. So where (which counties) are driving these increases?

COVID by County

County Data Table sorted by Case Rate – 7/24/21

So we’re continuing to see a large case rate in some rural Missouri and Arkansas counties. Nassau and Duval Counties in Florida have jumped onto the list. These two counties are both in the Jacksonville metro area. If you add Camden County, Georgia, (just north of Nassau county) into the mix, it looks like some sort of local spread event, perhaps. The outbreak might have begin in Camden County and worked it’s way down… This article from mid July indicates that only 28% of eligible people in Camden County had been vaccinated. This Jacksonville, multi-state metro area has an overall case rate and acceleration that might be driving much of the overall Florida numbers.

Therefore, I see basically three major local events in the top 20 or so counties: 1) Arkansas, Missouri, Oklahoma border area 2) Jacksonville, FL, metro area, and 3) Midland, TX (why?). This leads me to believe that this variant IS extremely transmissable — it has spread pretty quickly in these areas, but I believe these areas have relatively low vaccination rates.

Arizona COVID by County

Arizona Data Table – Sorted by Case Rate – 7/24/21

Above is the data for Arizona as of 7/24. Here we see the bottom four counties in case rate (and all with pretty low accelerations too) along the border. Note in the NYT visualization below that Pima, Santa Cruz, and Coconino Counties all have pretty dark colors, i.e., high vaccination rates. Mohave, Pinal, Maricopa, Greenlee, and Yavapi Counties all have the lowest vaccination rates. This is similar to what we see above… the Delta variant seems to be growing fastest in low-vaccination areas. I’m not sure if this trend holds… things may change. But for now it does seem like Delta is very transmissable, but very localized (and possibly highly correlated with low-vaccination areas). And fortunately, as you can see, deaths remain very low as of this date.

NYT Vaccination Map – 7/24/21 (https://www.nytimes.com/interactive/2020/us/covid-19-vaccine-doses.html) – Note that the tan color (GA, WV, VA, etc.) represents missing data.
COVID Case Rates and Accelerations (diameter) – 7/24/21

Above you can see in my map of case rates and accelerations by counties there are a couple of large regions of outbreak. One hovers over the Arkansas, Missouri, and Oklahoma border areas and the other hovers over Jacksonville and S. Georgia. This is a pretty good picture of how non-uniform the current COVID Delta Variant outbreak is. The outbreaks also appear to correlate strongly with the low vaccination (light green) areas on the NYT visualization.

COVID Update – 7/15/21: Is the Delta Variant Running Rampant??

I’ve been seeing lots of articles alleging that the rate of infection is shooting up across the country. LA County is re-ordering the wearing of masks indoors, even by people who have been vaccinated. Does any of this make sense?

State Data Table: 7/15/21

Above you can see the current rates. Anyone who has read this blog for a while is likely to notice that the case rates for each state (IROC_Confirmed) are still quite low (see the table for April 28th here for a comparison). If you look around at my older reports you’ll find that Arkansas’ rate of .229 cases per thousand persons is a pretty low rate compared to previous leaders which were 3 or more times higher. But are the rates growing each day (accelerating)? In some states we see non-trivial accelerations. Nevada’s acceleration (dIROC_Confirmed) is causing the case rate to increase by .0171 cases per thousand every day. Missouri is at .0182. However, most states’ accelerations (while they are non-zero) are fairly small. Texas is pretty close to zero. My guess is that their case rate is falling. California doesn’t even show up on this list (their case rate is .031 and their acceleration is .0021).

I suspect that some of the panic amongst our journalists is the fear of the case rates doubling or tripling again like they did last summer. Or perhaps there’s just not enough to write about? If you look below, you can see that there ARE some counties that have really high rates. Most of these are in Arkansas and Missouri. As these states share a border, this appears to be a local situation more than a US national trend. You can see that the case rates in Baxter County, Arkansas (in the north of the state near the Missouri border), are about 4 to 5 times higher than the overall state rate. The second highest case rate is in Taney County, Missouri, which is quite close to Baxter County. I can’t figure out why the case rate is high in Midland County, Texas. There’s nothing about an outbreak on their County COVID website, so who knows.

Do take note however, that the rate of deaths is extremely small. This is likely to do with the better resistance that vaccinated people’s immune systems make to an infection.

County Data Table: 5/17/21

Los Angeles County Case Rates over Time

Below you can see the Confirmed Case curve for Los Angeles. An increase in slope is barely perceptible today, but you can see that cases have essentially been flat since about February.

COVID-19 Updates: Jun 2021

As COVID numbers slow in my state (Arizona) and across the US, it’s difficult to see much in the way of trends. Here’s a quick update since the news outlets aren’t talking about the data much anymore.

Arizona Overview

Table: All Counties in AZ sorted by Case Rate (IROC_Confirmed) – 6/12/21

Things to note. 1) The case rate is very low, even in the highest county (Mohave). I do believe this is a strong indicator of “herd immunity” through vaccination and natural immunity. 2) The counties at the top of the list are fairly rugged, individualist counties. I’m not sure their vaccination rate, but I could imagine that it might be lower. 3) Maricopa (more permissive) and Pima (more strict) had very different approaches to governmental restrictions about COVID. But at this point, their numbers are pretty much identical when normalized by population. There are a lot of papers coming out evaluating the effectiveness of governmental action during COVID. They’re not being highlighted much, but in general there’s not much confidence that the governmental actions accomplished much. Here’s a small sign that might demonstrate that point. 4) Yuma and Santa Cruz are both border counties that have the highest cases and deaths per 1000 persons. They appear to have been most affected by unconstrained outbreaks in Sonora, Mexico. This may point to the outcomes experienced with little to no government action (on the part of Sonora). Combined with the point from 3) above, this might demonstrate that there is an effect from some level — even small — of government measures, but that at some point, government action becomes ineffective.

US Statistics

Tqble: Top 22 US States/Territories sorted by Case Rate – 6/12/21

This table shows us that the case rate is very, very low for the majority of US regions. The only two regions with any rate growth (acceleration) are New Jersey and Puerto Rico. The rest of the states have essentially zero change in their case rates (which as stated before, are already very low). New Jersey is very interesting, as they’ve had the most consistent rate growth of any state through the whole COVID pandemic. When other states’ rates would flatten out, New Jersey’s would keep creeping upward. They also have the highest death count per 1000 persons of any other state. No idea why this might be.

Chart: Top 8 states by Deaths per 1000 – 6/12/21
Chart: Cases per 1000 for selected states – 6/12/21

The above two charts represent 1) the top 8 states by deaths per 1000 persons and 2) Cases per 1000 for a selection of “interesting” states. I include the deaths chart just to show the crazy effect of the big outbreak in the Northeast during the first few months of the pandemic. It took most of the others in the top 8 until November 2020 to catch up to the death rates that New York and New Jersey had in July. The other chart shows that high cases and high deaths are not correlated. Note that the top three on this list don’t appear in the top 8 deaths chart. New Jersey and New York are the only two states that appear in both charts. Of interest is New York’s and New Jersey’s unique case slope. They is mostly linear between November of 2020 and May of 2021 where all the other states here experience steep surges offset by plateaus. No idea why this might be.

World Data

Table: World data sorted by Number of Cases on previous day – 6/12/21
Table: World Data sorted by Normalized Case Rate (IROC_c_n) – 6/12/21

These two tables sum up the two stories around countries around the world. The first shows the ones with overwhelming numbers (India, Brazil, Columbia, etc.) that make the news. The second shows countries that are disproportionately affected. In many cases, small countries like the Seychelle and Maldive Islands top the list, but you can see that Sweden, Czechia, and Chile are crowding them. These all have pretty high case counts for their populations. Finally, below you will note the countries that are experiencing high death rates normalized by their population sizes. These are places where deaths are very disproportionate. Note that Brazil and their near neighbors are high on this list and India is missing. The large numbers of deaths in India are just as tragic as deaths anywhere, but the ratio of deaths to people in Peru and Brazil are likely more overwhelming to those countries.

Table: World data sorted by Normalized Death Rates – 6/12/21

COVID-19 Update: Things are Slowing in the US, picking up Elsewhere

Here’s a quick update on what is happening in the US and around the world. See analysis below the images.

State Data Table, 5/9/2021

A bit over a week ago in my last post, Michigan was leading the US in case rates. Since then, their cases have collapsed and Michigan was replaced at the top by Colorado, then Oregon, then Alabama… This makes me suspect that these outbreaks (they’re all very small compared with the peak in January) are somewhat isolated. Above, the data tells us that the highest acceleration of cases is happening in Alabama but the largest slope (cases per 1000 persons per day) is in Oregon. It’s not surprising to see lots of cases in Oregon as that state has been very lightly touched to date. A similar effect is happening just north of Oregon in Washington. The sixteen states above are the only ones that show a daily increase in the case rate (dIROC_confirmed). The rest of the states are seeing case rates slowing.

Arizona Deaths due to COVID-19 along with moving average of Ratio – 5/9/21

The above chart shows something interesting that I have highlighted. The Arizona ratio of deaths in the over65 demographic to deaths in all other demographics is slowing significantly. What this might mean:

  1. The data is small (deaths are down significantly) and this is a statistical anomaly.
  2. The over 65 demographic — which seems to be getting close to “fully” vaccinated per the AZ DHS data — is being protected by the vaccine from severe responses to COVID. We all suspect that this is the case, but here’s some data showing a pronounced shift since about mid-March.

World Data

Raw Number of New Active Cases and Deaths on 5/8/21

Above you can see the new cases and deaths on 5/8 from the top 17 countries. There’s lots of news about India and the terrible things happening over there as their hospital system gets stressed, but in actuality, on a per capita basis, India, Brazil, and the US are in much better shape than the leading countries in the chart below. India’s 400K cases yesterday represents about .3 cases per 1000 people, which is about half the number of Peru from 5/8.

Number of new cases and deaths (5/8/21) normalized by population


It’s Been A While: 2021 COVID-19 Update

At some point in early 2021 the more mediocre articles about COVID in the popular media started to slow down and memes in social media began to disappear. Much of the focus in these places turned to vaccines and the new US administration’s approach. It seemed like a good time to slow down my COVID updates and instead spend time watching. For a while I have been concerned that overwhelming people with data and analytics about COVID was contributing to the overall problem of fear and distrust (although it seemed necessary in light of the poor communication from government and media). However, I’ve continued to collect data and run analytics. Here’s the latest data for those who are interested.

Topics:

  • United States Situation
  • World Situation
  • The Latest on Interesting Analytics

United States

Table of US States sorted by Case Slope – 4/27/2021

The above is the table that I have shown throughout the Pandemic. You can scroll back a few pages and see this table during the different outbreaks for comparison sake. Right now there is one big outlier, Michigan, interestingly one of the states with the most restrictive (or at least publicized) COVID policies. The good news is that Michigan’s current case rate is still only about half of what the highest state was during the winter outbreak. The next highest regions have significantly lower slopes. This is an unusual trend and may be indicative of the success of the vaccination policies that the states have put in place.

Table of Counties in Arizona sorted by Case Slope – 4/27/2021

Arizona has significantly lower Case Growth than other states right now. The highest counties in the state are those who were spared a bit more during the recent outbreak. This has been a pattern throughout… the virus finds regions that haven’t been hard hit and then runs for a while until it runs out of targets or temperatures move outside the virus’ comfort zone.

One metric that I have been tracking is the ratio of deaths in groups over age 65 to deaths in groups younger than 65. In Arizona, only around 13% of the population is over 65 but this ratio is still somewhere about 3:1. This is a sign of how overwhelmingly COVID has impacted the over 65 age group. During the first large summer outbreak in AZ we saw a ratio of about 2.3:1. During the most recent winter outbreak, we saw the ratio peak up over 3. This increase might mean that right now there are less susceptible people under 65 than there was during the summer of 2020. The green line on the chart above is the moving average of this ratio. The recent peaks in this line are primarily due to the small numbers of deaths being recorded now.

Here we see the case growth curves for both Maricopa and Pima counties with the number of COVID tests per day superimposed. This metric (number of tests) is not a perfect metric but it appears to be a solid indicator of upcoming acceleration or deceleration in the COVID case curve. You can see for yourself that when it starts trending in a direction, a change in the case curves comes 4-5 weeks later. Currently the number of tests is approaching the low water mark but this remains a good number to keep watching to give us an idea of whether there will be summer outbreaks again this year.

Arizona %Tests Positive by Day – 4/27/2021

This chart shows the percent of tests conducted yesterday with positive test results. The blue dots are the daily results and the gray curve is the best-fit line that describes the trend. The tests positive number hovered near 50% for a while and now is stable around 8-10%. It is concerning to observe that the curve shows signs of turning up again. If true, this may be an indicator of another summer outbreak in Arizona.

World Data

Table – COVID Data from Around the World, Sorted by Number of New Cases – 4/27/2021

India has been in the news recently for their large number of new cases and deaths. 323K new cases in a day would be enough to intimidate anyone. The raw numbers seem scary, but note that the case slope (IROC_c_n) is very low for India (.2724). What this means is that right now, as a percentage of their population, the rate of new cases is quite a bit lower than other countries (see below). If one considers case acceleration (dIROC_c_n), we still see that India’s number of an increase in .008 cases per 1000 persons every day is small compared to countries like Turkey, Columbia, and Argentina.

Table – COVID Data from Around the World, Sorted by Case Slope – 4/27/2021

We can see that India isn’t even in the top 10 in the world with regard to normalized case slope (IROC_c_n). Turkey, however, is very interesting with both a high raw count of cases and deaths, but also a very high normalized Case Slope. Turkey also has a very large population, but not nearly as many as India, so their numbers of new cases each day will be shocking (43K yesterday), but not as difficult to comprehend as the 323K new cases yesterday in India. So even though India isn’t as fully-saturated with COVID as Turkey or some of the South American countries, it’s still a problem for the world. India is one of the largest manufacturers (maybe the largest) of pharmaceuticals in the world. COVID vaccine manufacturing has dropped significantly since the start of India’s second wave. This is an example of how COVID can drive non-linear effects.

Updates on Interesting Analytics

Normalized Cases and Deaths by Latitude Range – 4/27/2021

I have showed the above a number of times during the pandemic. The trend still holds where the latitudes between -10 and 20 have experienced very few cases and deaths due to COVID.

Factors correlated with Cases per 1000 persons – 4/27/2021

I have also shown multiple revisions of my correlation studies over the last year. In the above we are demonstrating the levels of correlations of various measurable features with cases per 1000 for countries across the world. The top factors associated with COVID cases continue to be smoking and BMI metrics. What this says is that in regions where smoking rates and Body-Mass Indicies are high, we have seen larger numbers of COVID cases. It may not be surprising to see this. Population over 65 is also another feature highly correlated with Cases per 1000 and the inverse correlation of COVID cases with the prevalence of Tuberculosis in a country is still quite interesting. I know there were some studies into whether TB innoculations were somehow providing protection against COVID, but I lost track of those.

Factors Correlated with Deaths per 1000 persons – 4/27/2021

The above correlation is for death counts per 1000 persons. As with the Case correlation project, we see that smoking and BMI measures are strongly correlated with COVID deaths. Population size over age 65 is also (unsurprisingly) correlated with COVID deaths as well. For some reason, the growth rate of the country is inversely correlated with COVID deaths. Perhaps this is because a region that is growing is adding infrastructure like hospitals? This might seem to contradict the observation above that the number of hospital beds is correlated with COVID deaths, but my suspicion all along has been that countries with large hospital bed counts are probably recording more COVID deaths that go unrecorded elsewhere.

COVID-19 Cases and Deaths by Latitude

It’s pretty interesting to see that the COVID case/death trends by latitude have continued. I suspect some of this could be attributed to a lower population in some latitude bands combined with a focused COVID outbreak, but since this is population-normalized, it probably only applies at the 50 degrees and northwards latitudes…

Equatorial regions still have a significantly lower case and death count. Poorer reporting could be partially involved, but can’t describe this big of a difference. Surprised this isn’t discussed more.

COVID-19 Cases/Deaths per 1000 persons by Latitude – 2/11/2

COVID-19: Is the Winter Outbreak Over?

Around the end of January I posted this table and about half or less of the states were showing deceleration of their COVID case growth rates. This could be seen in the dIROC_confirmed column where negative numbers are deceleration and positive numbers are acceleration. Now, about 12 days later, every state has negative growth acceleration and the overall growth rate numbers are much lower. This happened very quickly. You can see that Arizona — who had the largest growth rate in the country as of 1/31 — now is much lower and has the largest deceleration number in the US.

As winter weather patterns still differ across the US, I’m curious if this reflects growing numbers of COVID vaccinations

COVID-19 Data by State – 2/11/21

Below are the Arizona numbers by county. One interesting point to note is that Maricopa County has a higher deceleration number and a lower overall case growth rate than Pima County. This is counter-intuitive because Pima County has enforced much more restrictive COVID policies during the entire outbreak. I have heard (but haven’t researched) that vaccines are easier to get in Maricopa County due to a more efficient rollout by their County Medical Office. Perhaps this is reflected in these numbers?