With COVID-19 declared as a pandemic, one big question in every body’s mind is just how many COVID-19 positive cases are out there. At the outset let me state that as of 18th
March, 2020 there could be more than 800 thousand COVID-19 cases in the world and
more than 140 thousand in India. While professionals and researchers differ in
estimate there seems to be a consensus that the COVID-19 cases are far higher
than what is being reported. For instance, Dr. Mathew Carter from Connecticut
health officials hints that there could be 100 untested positive cases for
every confirmed case. In the subsequent part, I will present my analysis of the
number I claim.
There are serious reasons to
believe, that the number of confirmed cases are hugely under-reported and doesn't represents the true picture. The number of confirmed COVID-19 cases depends upon how
many suspected cases are being tested for the disease and what is the criteria to determine
suspect. It can be argued that, since the disease is novel and with the great speed with
which it spread across the world, most countries did not had enough time to
plan for detecting suspects and for arranging the resources to conduct lab
tests on a required massive scale. The number of labs and the test kits available
with many countries are minuscule compared to the number of tests that would
ideally be required to be done in the given scenario. As a result, most
countries have put stringent criteria to decide who can be tested. This means, many
patients with actual COVID-19 will not get tested, due to the criteria and
hence will not appear in the count.
With this understanding of resource constraints, it is reasonable
to believe that the countries with sound economy will be better off in arranging
resources and conducting tests at a larger scale, compared to countries with
poor economy. To examine this, I ran a correlation between COVID-19 reported cases
per million population with the GDP (PPP) per capita income of various
countries. As per my expectation, the correlation came positive at 0.26, which
means that per-capita income of country is positively associated with the reported confirmed COVID-19
cases per million. In simple words, richer countries are reporting more number
of confirmed COVID-19 cases compared to poorer countries. While the correlation
coefficient is mild to moderate, it does indicates that there could be
significant number of undetected positive COVID-19 cases, specially in countries with low per-capita income. A comparison of cases per million population of top and
bottom 25% countries by economy also showed a statistically significant difference (p =
0.007), with top 25% countries showing much higher number of cases compared to
bottom 25% countries. To ensure that other factors are not confounding the
result, I checked for the effect of geographic location and population. For
geographic location, countries located nearby and having different economy, did
showed remarkably different number of cases per million population. For instance, USA has reported 23 confirmed cases per million population which is a staggering 32.8 times that of Mexico, which has reported just 0.7 case per million. This is despite the fact that they share border and could be posibly because USA is much stronger economy than Mexico. In general also it can be observed that,
irrespective of the countries location in the world, the rate of COVID-19
penetration was generally high in high income countries and generally low in
low income countries. The co-orelation between population and cases per million population also does not exist, with correlation coefficient coming at -0.03. Thus geography or population doesn’t seems to have any role in the penetration
rate of COVID-19.
There is no justifiable reason to believe that poor countries will have significantly lower number of COVID-19 cases, as is being reported by respective governments and it just suggests that the data on number of
COVID-19 is highly under-reported. As data is key for fighting this menace, it
is imperative that we have an idea of a more reliable number of COVID-19 cases. Estimating the
actual number of cases would be difficult as it would require several
assumptions to be made. One approach could be to assume that COVID-19
infections spreads at a similar rate in all countries irrespective of their
population, economy, geography or climatic condition and apply the most
reliable rate to all countries. As I have argued in first paragraph that resource
rich nations are in better position to test COVID-19 in large numbers, we can
use their figures as somewhat reliable and estimate the number of cases for
other countries. For this, I took the top 50% countries by economy, using GDP (PPP)
per capita, and calculated the COVID-19 cases per million population by combining
all of their cases and all of their population. The result comes to 112.7. In
contrast, the cases per million population of bottom 50% countries by economy is
mere 37.4. If we ignore the rate of bottom 50% countries, considering the lack
of tests being conducted, and use the rate obtained from top 50% countries, we
can estimate how many COVID-19 cases could be there.
This would mean that for India, with a population of 1.3
billion and 112.7 COVID-19 cases per million, there could be 146,510 people who
would have acquired COVID-19 till date, as against the reported number of 168 confirmed
cases reported. This is not even the tip of the iceberg. Similarly, for the
world with population of 7.7 billion, the number of COVID-19 cases could be
alarming 867,790 against 216,425 reported so far.
Disclaimer – This is my independent analysis and is
subjected to the assumptions stated in the article. Data taken from WHO situation
reports, World Bank and the online site, www.worldometers.info. The data is as of 18th March, 2020
Arif Raza
