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Opinion| How does India compare with other countries on testing for coronavirus?
6 min read.Updated: 29 Jun 2020, 02:31 PM ISTBijendra Nath Jain
India publishes data on the number of covid-19 samples tested, while many others publish data on the number of people tested
This fact may be kept in mind when we compare number of tests conducted by different countries
Given that many voices in India are calling for more covid-19 tests to be conducted in India, the question is: how does India compare with other countries on testing for covid-19?
We compare India’s record on testing with that of 9 other countries that have been impacted the most by covid-19, viz. USA, Brazil, Russia, Spain, UK, India, Italy, Peru, Germany, and Iran. Where feasible, we will compare India’s test record with the next set of 10 countries that are similarly impacted.
We base the comparison on a number of metrics using data from Our World in Data. In particular, we consider 3 metrics, viz. (a) total, or cumulative, number of tests per 1000 people, (b) number of daily tests, per 1000 people, and (c) number of tests per confirmed case. And we look at the metrics “as on" a certain date, as also the manner in which the metrics have changed over the last few weeks. Further,
• India is one 86 countries that officially publishes data on covid-19. There are several other countries that do not.
• Since publication of data is not synchronized globally and not in any globally accepted format, cleaning the data and adding it to a databases takes time. Therefore, the latest data on tests conducted by different countries may not be available for the same date.
• India publishes data on the number of covid-19 samples tested, while many others publish data on the number of people tested. This fact may be kept in mind when we compare number of tests conducted by different countries.
Total number of tests per thousand people:
From data (Figure1) for 20 countries that are most impacted by the pandemic, India with 5.63 tests per 1000 people till June 26, 2020 shares the bottom quartile with countries such as Mexico, Bangladesh and Pakistan. The median for the 18 countries is around 47.
Total covid-19 tests per 1,000 people, Jun 28, 2020
Figure 2 simply confirms that the total number of tests per 1000 people in the last 10 weeks has increased significantly, but not in relation to the other countries. That is, India continues to be ranked at the bottom of the stack amongst the 9 countries (other than Brazil).
Total covid-19 tests per 1,000 people
One should note that on the basis of 2016 per-capita GDP India is placed in the 3rd quartile. Similarly, India is placed in the 3rd quartile of 2019 Human Development Index by UNDP. Clearly, inadequate testing in India is not commensurate with our economic strength or the stage of human development – we should have done better on testing for covid-19.
One argument that can be put forward to explain the low rate of testing is that covid-19 pandemic arrived in Brazil, Bangladesh, India and Pakistan in second half of March or early April - measured by date on which the 1000th confirmed case was detected (see Table 1). But, that is no reason for the number of daily tests to be not ramped up with increasing number of confirmed covid-19 cases.
Growth in daily number of tests:
Even as the total number of tests per 1000 people performed in India (as on June 26) is small, the number of daily tests (averaged over the last 7 days) performed is similarly small (0.14 per 1000 people on June 26). See Table 2. On this count as well, India is in the bottom quartile, together with Bangladesh, Mexico and Pakistan.
However, from Figure 3, the number of tests performed on a given day has grown more-or-less linearly from 0.037 tests per 1000 people on May 1 to 0.14 tests per 1000 people on June 26 - an increase from 51,500 tests on May 1 to 192,800 tests on June 26 – an increase of 141,300 in 8 weeks. If the trend continues, the number of tests performed is likely to be nearly 265,000 on July 24, and 335,000 tests on Aug 21. Consequently, the cumulative number of tests performed will be at most 3 times as many tests till August 21, or 17.0 tests per thousand people. This could push India into the 3rd quartile, at par with Iran, for instance, but far short of tests conducted by other countries ranked similarly in the third quartile.
Daily covid-19 tests per thousand people
The two metrics considered above, cumulative or daily tests per 1000 people, are obviously related. The number of daily tests helps understand whether individual states have begun to ramp up its testing capacities. The third metric we consider next, tests per confirmed case, helps evaluate the “cost" of discovering a new covid-19 positive case. Equivalently, the metric helps gain an understanding of how widespread the pandemic is, or how well testing is targeted.
Number of tests performed per confirmed case:
Yet another metric tracked by many countries is the number of tests performed per confirmed case (averaged over all confirmed cases till June 26). From Figure 4, it is clear that India appears to be doing better - the number of tests performed per confirmed case is 15.9. This suggests that one in every 16 tests results in one covid-19 positive case.
Total number of covid-19 tests per confirmed case, Jun 28, 2020
How has this changed over time? Figure 5 gives an idea of how the number of tests performed per confirmed case on a given day has changed over the last 10 weeks. While for India the ratio of number of tests performed per confirmed case, averaged over all confirmed cases till June 21, is 15.9, the ratio has changed from 24.92 on April 17 to 12.28 on June 26. This has a major implication, the “positivity", or yield, defined as number of positive cases discovered per 100 tests on a given day, has increased 100% from 4.01 on April 17 to 8.14 on June 21. This is either because the tests are better targeted today than what they were 10 weeks ago, or the virus is significantly more widespread today than what it was 10 weeks ago, or a combination of the two.
Tests conducted per new confirmed case of covid-19
Incidentally, the experience has been very different in Russia and UK where testing has been exceptionally aggressive. As a consequence, the ratio has increased significantly to 40 and 54, respectively, in the last 6 to 8 weeks. The yields are correspondingly down to 2.5 or so.
To summarize, given India’s standing in the world in respect of per capita GDP, ranking on UNDP’s Human Development Index, and the urgency for India to rid itself of the pandemic, the number of tests for COVID-19 conducted in India is far fewer than those compared to other countries. In particular:
• India is in the bottom quartile in the world ranking based on the metric, “cumulative number of tests per thousand people". This fact has not changed over the last several weeks.
• The number of tests performed daily in India has increased significantly in the last 8 weeks. If this trend continues the number of tests performed will grow 75% in next 8 weeks. Consequently, the total number of tests performed per thousand people will be 3 times as many on August 16, pushing India into the 3rd quartile, at par with Iran.
• The near-linear increase in daily tests is not enough, given that the number of confirmed cases in India doubles every 3 weeks – a fact that shows up in India’s deteriorating record on the metric, number of tests per number of confirmed cases.
• With respect to the metric, “number of tests performed per confirmed case", India is doing better than many countries. Over the last 10 weeks, however, the number of positive cases detected per 100 tests has increased 100%. That should be motivation enough for India to significantly increase its testing capacity going forward, while exploring the use of pooled testing where feasible.
The author is Visiting Distinguished Professor of Computer Science at IIIT Delhi, and Honorary Professor at IIT Delhi. Views expressed are personal.