Weather and spread of COVID-19

One of the mysteries regarding the spread of COVID-19 is that the African countries and India have been largely spared. In fact worldometer finds that so far, India has had a total of 332 cases with 5 deaths with the last death being that of a 69-year old Italian tourist. Why is that the case?

A study by University of Maryland, which is referenced in this article states that:

The University of Maryland mapped severe COVID-19 outbreaks with local weather patterns around the world, from the US to China. They found that the virus thrives in a certain temperature and humidity channel. “The researchers found that all cities experiencing significant outbreaks of COVID-19 have very similar winter climates with an average temperature of 41 to 52 degrees Fahrenheit, an average humidity level of 47% to 79% with a narrow east-west distribution along the same 30–50 N” latitude”, said the University of Maryland.

“Based on what we have documented so far, it appears that the virus has a harder time spreading between people in warmer, tropical climates,” said study leader Mohammad Sajadi, MD, Associate Professor of Medicine in the UMSOM, physician-scientist at the Institute of Human Virology and a member of GVN.

There are two graphs from study that are particularly relevant with the first “image below, the zone at risk for a significant community spread in the near-term includes land areas within the green bands.”

The second image below is of relevance because “as of right now reported cases as a function of latitude, about one-third of the world’s population is below 22.5°N yet has not experienced meaningfully high levels of infections.”

Does the same correlation exist within US, i.e. the virus is more prevalent in the North? Based on the above image one would think so. This study collected the population data from:

https://simple.wikipedia.org/wiki/List_of_U.S._states_by_population

The latitude data is from the following two websites:

https://inkplant.com/code/state-latitudes-longitudes
https://www.latlong.net/category/states-236-14.html

The latitude data from the two sites differs slightly with mean difference of 0.21 and standard deviation of 0.81.

If we then divide the data into two bins of above 41N, which includes the states of Pennsylvania, Nebraska, Connecticut, Rhode Island, Iowa, Massachusetts, New York, Wyoming, Oregon, Vermont, New Hampshire, Idaho, Michigan, South Dakota, Wisconsin, Maine, Minnesota, Montana, North Dakota and Washington, and below 41N, whilst discluding Alaska, you get the following numbers.

Below 41N

Total cases 9,099
Total deaths 127
Total population 249,756,021
Total cases/1M people 36.4
Total deaths/1M people 0.51

Above 41N

Total cases 15,668
Total deaths 161
Total population 77,812,978
Total cases/1M people 201.4
Total deaths/1M people 2.07

The numbers are markedly different. Of course The Economist tries to stoke the fear by stating:

Fears are rising that the world’s second-most populous country might be on the brink of a big covid-19 outbreak. Until now India has been lucky with this coronavirus. It has relatively few visitors from the early centres of the pandemic—China, Italy and Iran. And Indian governments, at both federal and state levels, have been strikingly forceful in their response to the virus, with public-information campaigns saturating the television airwaves, and recorded messages pushed to mobile phones. So the number of Indian cases so far can be counted in the scores. But India has so far tested only a few thousand people, and some experts think it already has thousands or tens of thousands of cases. If so, decades of under-investment in public health have left India ill-prepared, with not enough doctors, beds or equipment for its 1.3bn people even in ordinary times.

Based on the Univ of Maryland study this is unlikely. Of course what it does imply is that the areas below the equator will suffer a similar fate in their winter.


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Rebel Yell

It will be interesting to see how things play out in India. Although hotter, population density in India could make it another story. We’ll know in a few weeks. As you indicate, The Economist is just a joke paper these days.

Arran Gold

From the worldometer site, if you look at total cases and cases on a per capita basis these are the top two nations.

San Marino 160 4,715
Faeroe Islands 92 1,883

San Marino is understandable because it is completely enclosed by Italy. But if you look at the islands you wonder how the hell the virus got there but then everybody goes everywhere. So for The Economist to assert that India has fewer cases because “It has relatively few visitors from the early centres of the pandemic—China, Italy and Iran” is absurd. Typical bloviating from that newspaper.

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