Is COVID-19 Primarily a Disease of Wealthy Countries?

or are wealthy countries giving poorer countries their diseases?

Wealth and COVID-19: a Possible Correlation

First posted April 7, 2020

Rewritten June 19, 2020

Last updated September 1, 2020

Introduction

I wrote this article in early April after observing that countries that were hit hardest by the COVID-19 pandemic tended to be predominately wealthy countries. One usually expects epidemics to hit poor countries much harder than wealthy countries; but COVID-19 appeared to be an exception.

On April 7 and April 28 the correlation between GDP (2017, by rank) and number of confirmed COVID-19 cases (also by rank) was either moderate (0.3≤ρ<0.5) or high (ρ≥0.5) depending on how the countries were chosen. (see table below)

Since then, I've run correlations on March 21 and semi-monthly since April.

The correlation in March was not so strong as in April. Also the correlation fell off in May, but still remained moderate. In June, some of the correlations fell below the moderate range and in July and August the correlations continued to fall and were in some cases negligible.

There appear to be two factors here:

1. Some wealthy countries: notably New Zealand, Australia, and many East Asian countries such as China and South Korea brought their epidemics under control and were surpassed in number of COVID cases by less wealthy countries. Indeed, removing the Asia-Pacific countries and all East and Southeast Asian countries from the mix, the correlation held somewhat better but still has tapered off considerably. (see table below)

2. The pandemic has raged out of control in some relatively poor countries: most notably Afghanistan and Iraq, which are under US occupation, in fact, if not in name. This has brought the correlation down from its April levels too. Those familiar with Jared Diamond's “Guns, Germs and Steel” will recall that spreading disease has typically been one of the most effective ways in which wealthy countries have devastated poorer countries.
Also of note is that countries that were hit early by the pandemic, and brought it under control early, tend to have far fewer cases overall than many countries in which the pandemic hit later. The pandemic hit late in Brazil, India, Russia, South Africa, Colombia, Argentina and Mexico which are now within the top 10 ten countries in number of COVID-19 cases.

The United States hit its first peak in April. It was unable to bring the pandemic under control. It appears to have passed its second peak now, over twice as high as the first one. The United States has ranked number 1 in COVID-19 cases since early April.

Recent research shows that the COVID-19 virus is mutating and appears to be becoming more contagious and virulent. This could at least partially account for why later outbreaks appear worse than earlier ones.

It would seem to make more sense to use GDP per capita and COVID cases per capita, rather than to correlate by rank. I tried this; but the results were not encouraging. There was no correlation to be found.

Since the countries that have a large population tend to also have a high GDP, I tried correlating population with number of COVID-19 cases. The correlation gradually increased from -0.02 in March to 0.39 in mid and late August. This makes sense, as all other factors being equal, infections should eventually become proportional to population.

Possible Causes for Observed Correlations

Here are some likely causes for the observed April correlation between GDP and confirmed COVID-19 cases: I think the first three are probably the most important from the standpoint of this article.
1. People in wealthy countries tend to be more mobile and therefore better able to spread the virus.

2. Many people in wealthy countries tend to be lacking in social discipline and feel a sense of entitlement. E.g.: “Screw this social distancing crap, I gotta go do my thing.”

3. People in poorer countries tend to have a greater exposure to a variety of harmful microbes and may, therefore, have more robust immune systems. (This was suggested to me by a recent article in Science by Linda Nordling.)

4. More testing is carried out in wealthy countries.

5. Many people in poorer countries have enough problems staying alive and healthy already without worrying about a new virus with at most a 5% mortality rate.

6. Poor countries may be less likely to report confirmed cases than wealthier countries.
In the April draft of this article, two other possible causes were also mentioned:
7. Genetics: During April, most (but not all) of the countries with a large number of cases per population size tended to be European or have large populations of European ancestry.

8. Perhaps this is all simply random noise.
In view of data since April, both seem highly unlikely.

Two Examples

It is also worth noting that some of the April observations that COVID-19 is hitting wealthy countries much harder than poorer countries continue to hold on a regional basis.
Israel and Palestine: In early April, Israel, with somewhat less than twice the population of Palestine, had 9,000 confirmed COVID-19 cases. By contrast, Palestine had only 254. By the end of August, Israel had 117,000 cases to Palestine's 23,000 cases. This is in spite of the fact that Israel has so many more resources than Palestine and continues to sabotage Palestinian efforts to fight the pandemic.

Israel has a population of around 9 million compared to Palestine's 5 million

Gaza, which is part of Palestine, has been living under almost complete lockdown without adequate clean water or medicines since 2007, due to the Israeli blockade.

Recently Israel demolished a COVID-19 testing center in Hebron on the West Bank of Palestine.

Saudi Arabia and Yemen: The Saudi coalition has been waging a brutal one-sided war against Yemen for years with the help of the United States and other western countries. In early April, Saudi Arabia had 2,600 confirmed COVID-19 cases. Yemen had not one single confirmed case. By mid-August, Saudi Arabia had 297,000 cases and Yemen only 1,900. Saudi Arabia's population is about 15% larger than Yemen's.

In truth, if I lived in Yemen amidst daily bombings, starvation and a cholera epidemic, I would not be too concerned about a little respiratory virus with at most a 5% mortality rate. So let's keep all this in perspective.
It should also be noted that some of the world's poorest countries are among those with the fewest confirmed COVID-19 cases — for example, the African countries: Burundi and Uganda.

I was happy to note in Linda Nordling's article that medical researchers in Africa are looking into this. Apparently, they have not reached a consensus as to the cause yet, although it appears that many Africans have developed COVID-19 antibodies but have not exhibited symptoms. This suggests cause 3 above.

Data Sources

The data for the table below come from these two pages at worldometers.info:
COVID-19 cases by country

GDP (2017) by country
Note: The data used below from worldometers.org are as reported at the time, which may or may not represent the situation on the ground faithfully. What's more, historical data have a way of changing as folks discover anomalies and errata. I have made little effort to revise historical data.

In spite of these drawbacks, I suspect that the correlations below strongly supports the findings that COVID-19 was originally a disease primarily of wealthy countries and has since spread into less wealthy countries.

Correlations, Tables, and Scatter Plots

The table below gives five different correlations on various dates from mid-March to the present at approximately semi-monthly intervals. The first four correlate COVID-19 cases by rank on the specified date with 2017 GDP by rank. The final correlation is between COVID-19 cases by rank and population by rank:
(a) Correlating number of COVID cases by rank with GDP by rank using all countries either in the top 50 in GDP (2017) or the top 50 in COVID-19 cases on the specified date or both.

(b) Like (a), but with Asia-Pacific, East Asian and Southeast Asian areas removed: The 12 countries and territories removed are: China, Japan, South Korea, Hong Kong, Thailand, Vietnam, Malaysia, Singapore, Philippines, Indonesia, Australia and New Zealand.

(c) Like (a), but with the three greatest outliers in each direction removed.

(d) Like (a), but using only countries in the top 50 in both categories.

(e) Like (a), same countries as in (a), but correlating number of COVID-19 cases by rank with population by rank instead of GDP.
I intend to continue running these correlations on a semi-monthly basis.

Here is a link to a sequence of scatter plot for the correlation in (a) above on selected dates.

And here is a link to the data used in the scatter plots and in the correlation table below.

I have not been very faithful in updating the scatter plots and data table linked to above.

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table