COVID-19 and the Great Convergence

By Kent R. Kroeger (Source:, June 12, 2020)

I’ll rip my ear hairs out if I read one more article about how islands have been so effective at controlling COVID-19.

New Zealand, Hawaii, Iceland, Singapore and South Korea (which is effectively an island given its infrequently crossed land border with North Korea) did a great job defeating COVID-19.

So, if I understand the lesson, when the next pandemic hits, policy step number one is to live on an island.

Got it.

For the rest of us, we need real information on how to defend against the coronavirus and its genetic cousins to follow.

Unfortunately, the U.S. mainstream media deals only in canned narratives when it comes to the COVID-19 pandemic — its either: (1) the Republicans are a bunch of anti-lockdown, anti-science bumpkins who put their 401ks ahead of human lives, or (2) the Democrats are fear-mongering proglodytes using the pandemic to advance the oppressive power of their postmodern Menshevik state.

What these two narratives miss is reality, even as some aspects within each are true — which is precisely why both are seductive and dangerous.

They can’t tell you the truth because, frankly, it wouldn’t attract an audience in today’s hyper-partisan landscape. The ongoing rampage of the Mean Orange Man is one (perhaps only) reason The New York Times and CNN are profitable in today’s over-crowded, highly-competitive entertainment milieu. On the other side of the dung heap, coverage of the existential threat of leftofascists to our God-endorsed democracy and Jesus’ two-thousand-year reign on Earth has been Fox News’ golden goose for over 20 years now. They aren’t going to change their news chyron because I believe objective, non-partisan journalism has an audience.

Given the narrow motivations of today’s news media, why wouldn’t their news coverage of the coronavirus pandemic be full dramatic but marginally relevant info-twaddle?

At this point, most of the American news audience is too conditioned to accept anything else.

The Great Convergence

But there is one feature of the coronavirus in the U.S. that has received sparse attention, even though it may represent the most important characteristic of the virus’ spread within the country.

The biggest story of the COVID-19 pandemic in the U.S. may be that its daily rate of spread is converging across all 50 states (and the District of Columbia), with little regard for the specific state-level policies implemented to suppress and mitigate its advance.

In other words, most of the states will eventually catch up with New York, New Jersey, Connecticut and Massachusetts in terms of cases and deaths per capita (after adjusting for population density).

New York, New Jersey , Connecticut and Massachusetts took a devastating hit from the coronavirus early despite implementing some of the strictest lockdown measures in the country, suggesting that the virus was already distributed through those populations before the lockdowns. While states such as Florida, Georgia, Texas and California have benefited from a much slower (“flatter”) spread of the virus despite implementing their lockdowns late (California being an important exception).

The good news for New York and the other densely-populated Northeast Atlantic states is that the virus may have already passed through their most vulnerable populations. The bad news for California and the other warm, lower latitude states may be that this has not yet happened.

Of course, these relationships are subject to change as this pandemic progresses.

Convergence is inevitable, but how each state gets there isn’t

Figure 1 (below) is derived from the coronavirus database at the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University and shows the day-to-day changes (per capita) in new coronavirus cases for the eight most populous U.S. states.

These eight states represent 48 percent of the U.S. total population. In terms of coronavirus policy differences, three of those states (Florida, Georgia, and Texas) were relatively slow to impose statewide lockdowns and relatively quick to ease them once the peak of the health crisis appeared over in mid-May.

At first glance, the chart’s most striking feature is New York’s dramatic rise in coronavirus cases from mid-March to mid-April (and dramatic fall in new cases thereafter). Equally interesting (to me at least) is the relatively slow climb for the other seven large U.S. states — which is probably a function of the population density of states along the northeast Atlantic corridor.

Figure 1: Number of daily new COVID-19 cases per 100k people for the 8 most populous U.S. states (through June 10, 2020)

Data from Center for Systems Science and Engineering (CSSE) at Johns Hopkins University; Chart by Kent R. Kroeger; Data covers period from February 21, 2020 to June 10, 2020.

However, another takeaway from Figure 1 is the convergence of the new COVID-19 case rates over time. At the end of April, the average number of new cases per day for every 100K people ranged from 2.3 (Florida) to 24.1 (New York). By June 10th, the average number of new cases per day for every 100K people ranged from 2.8 (Ohio) to 6.3 (Illinois).

You don’t need to be a statistician or an epidemiologist to see that new case rates have become more the same than different since the start of this health crisis.

Yes, there are still substantive state-level differences which can (and will) have a meaningful impact on the final coronavirus case and death rates. And variations in public policies in response to this health crisis likely will be needed to explain those outcome differences. And it is also critical to note that California, Florida, Georgia and Texas are still at or near their peak in daily new COVID-19 cases.

This health crisis is far from over.

In the larger scheme of things, despite substantively divergent coronavirus policies across the eight states in Figure 1 (Florida, Georgia and Texas being regularly chastised in the media for not being more aggressive in stopping the virus), all eight states are becoming more alike than different over time.

I call it the Great Convergence.

Isn’t that convergence inevitable — and therefore uninteresting — given that all the 50 states (plus D.C.) will reach zero new cases-per-day at some point?

Yes, in the long run, all the states will converge towards zero new cases per day. But how states get there is important. Specifically, how many people will die by the time the states stop registering new cases?

As of today, New York, Illinois, and Pennsylvania (three states with aggressive coronavirus suppression and mitigation responses) exceed the other five most populous states in COVID-19 deaths per capita by a factor of two or more.

However, there is evidence that the states are becoming more homogeneous over time in COVID-19 case and death rates. While few states will ever match New York’s approximately 1,600 COVID-19 deaths (per 1 million people), Figure 2 shows that the standard deviations across states in their case and death rates have been going down since April 1st.

Figure 2: The Slow Decline of Standard Deviations in State’s COVID-19 Case and Death Rates

Data Source: Center for Systems Science and Engineering (CSSE) at Johns Hopkins University; Chart by Kent R. Kroeger (

Considering the percentage of coronavirus news coverage dedicated to promoting (or dismissing, if you are Fox News) the aggressive lockdown policies recommended by most epidemiologists and public health experts, heretofore, those mitigation measures have not repaid the effort, particularly in terms of COVID-19 deaths per capita.

Some final thoughts

Remember the “flatten the curve” graph (Figure 3) often shown in the media at the beginning of the pandemic?

Figure 3: “Flattening the Curve”

Epidemiologists generally agree that the value of virus protective measures (e.g., lockdowns, social distancing) is to distribute the number of new cases more evenly over time, thereby putting less pressure on the healthcare system and saving lives. “Flattening the curve” also gives researchers more time to develop effective treatments and vaccines.

Recall Figure 1 (above) where New York’s distribution of new cases over time looks much more like the “without protective measures” curve in Figure 3, while the other seven states have much flatter curves. California and New York were two of the first states to issue statewide lockdown orders (March 19th and 20th, respectively); yet, New York’s new case curve has a much higher, more narrowly-shaped peak, while California’s is much flatter. More importantly, California’s COVID-19 death rate per capita is significantly lower than New York’s (128 deaths per 1 million people versus New York’s 1,587).

What happened? Why were epidemiologists accurate for California, but not so much for New York? Three possible (and preliminary) explanations include: (a) the coronavirus prevalent on the U.S. East Coast may have been more contagious and lethal than the version prevalent on the West Coast, (b) the virus was embedded earlier and deeper on the East Coast than previously thought, and (c) the population densities on the East Coast were more favorable for hosting and spreading the coronavirus.

But even if those disadvantages faced by New York are true, California’s case and death rates may yet approach New York’s when this pandemic is finally over.

Similarly, the current surge in new coronavirus cases in states that had previously lagged in its growth (e.g., Arizona, California, Florida, Georgia, North Carolina and Texas) may be less a function of poor policy responses by those states and more the result of their advantages over the Northeast Atlantic states as well as the characteristics of the virus itself.

As we often are reminded during this pandemic, the coronavirus is more in charge than politicians and experts care to admit.

  • K.R.K.

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