Why Northern and Southern Hemispheres are worlds apart when it comes to Covid-19 spread

While Covid-19 cases have been reported by 209 countries worldwide, a closer study of their geographic locations reveals some interesting numbers and conclusions. In the northern hemisphere, a total of 171 affected countries fall while only 36 are in the southern hemisphere – that is, 82.6 percent of the affected countries are from the north of the equator and only 17.4 percent are from the south.


by Niranjani Jesentha Kumari Prabagararaj

Updated: Apr 10, 2020 16:06 IST

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Two hemispheres

When we see at the number of cases in the two hemispheres, the difference gets bigger – 96.84 percent of the cases are from the north and just 3.16 percent from the south. 

In comparison, the northern hemisphere accounts for 98 percent of the total number of deaths recorded, while the southern hemisphere accounts for just 2 percent (1.765 out of 88.640).

This indicates that generally speaking, there is a strong association between a country's geographical position and COVID-19 severity (in terms of number of cases and mortality rate). A perfect example is a contrast between the U.S. and Australia-the third largest and sixth largest countries in the world. While the US has reported over 4 lakh cases and 14,000 deaths, Australia has just registered 6,104 cases and 51 deaths.

There are, of course, many variables that are responsible for the severity of COVID-19 in a country – successful lockdown and social distancing steps, the timing of international travel bans, percentage of the old age population, etc. But between these, the nation's geography seems to be a primary factor.

Francesco Ficetola, Ph.D. in environmental sciences, says, "A climatic impact is possible, for example, because we are more vulnerable to respiratory system infections during cold periods (winter). Mortality disparities are most possibly linked to susceptibility.

It explains the rapid spread of the virus during February-March in the northern hemisphere-for them the peak winter season. The less serious impact of the virus in the southern hemisphere where it was summer, is often described as a corollary.

Dr. William Schaffner, a specialist at the Vanderbilt University Medical Center in Tennessee, adds that in the next winter season, the virus could begin a loop and return to the northern hemisphere.


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