Research debunks claim of India’s low COVID fatality rate

The Narendra Modi government has bandied the relatively low COVID death count in India as evidence of its success in tackling the pandemic. Despite the incessant climb of India’s COVID caseload and the mounting death tally, the Case Fatality Rate (CFR), which measures the percentage of deaths among those infected by the disease, was still only about 2 per cent in early September. In his recent Mann ki baat podcast, Modi emphasised the low CFR to claim that India is better off compared to many other countries.

However, a recent paper published by the National Bureau of Economic Research in the US by three Indian-origin academics, Minu Philip, Debraj Ray and S. Subramanian, debunks this claim as an illusion arising from a statistical anomaly.

The study, by making statistical adjustments that are warranted by the peculiar demographic characteristics — in particular, the fact that India is a relatively “young” country — demonstrates that the smugness is dangerously misplaced.

Significantly, the researchers show that behind the aggregate CFR numbers lurks the disturbing reality of a pandemic that has hit India hard. That it comes at a time when the Indian COVID tally scales new heights, racing towards the five million mark, makes the study an exemplary example of academic research serving a greater purpose.

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From the beginning of the pandemic medical experts, epidemiologists and health officials across the world have repeatedly said that the disease is particularly severe on the elderly — particularly those with co-morbidities — implying that the young were relatively safe. This does not imply that the young are completely safe, it only means that younger people, on average, have a better chance of surviving.

This study demonstrates that in proportional terms far more younger Indians have fallen victim to the pandemic than they have in the rest of the world. In effect, India’s youthful demographic profile, which, statistically speaking, ought to have offered protection from COVID, has failed to provide a “natural” insurance in the pandemic.

“Adjusting” CFR to assess Indian Performance

On the face of it India’s low CFR, compared to other countries, ought to reflect the demographic reality that India is relatively young. According to the 2011 census, the latest available, only 8.6 per cent of the Indian population were above the age of 60.

More importantly, a little more than 50 per cent of India’s population is concentrated in the 20-60 age group years. The median age of the Indian population is 26.5 years, compared to 43 years in Europe and the global average of 31 years.

Generally, a low aggregate CFR for a country like India implicitly reflects a demographic advantage, which, in the specific case of COVID, confers a “natural” protection against fatality. On the other hand, countries like Italy may be expected to have a high CFR simply because the proportion of the population that is aged is among the highest in the world — in fact, second only to Japan.

Thus, because different countries have different demographic profiles, a comparison of India’s performance in combating the epidemic with other countries requires that the aggregate CFR be broken down into age-wise distribution of cases.

This is exactly what the paper does, by breaking the aggregate CFR statistically. It seeks “to approximate” how India would have performed “if it had the age-specific case fatality rates of these comparison countries.” The study compares India with 14 countries from different regions of the world. The list is diverse, including countries such as China, Japan, South Korea, Spain, Italy, Switzerland, and South Africa.

The demographic dividend squandered

The study reveals two striking findings, both of which enable an assessment of how successful India has been in coping with the pandemic.

First, the study shows that the Indian working-age population — aged between 20 and 60 years — who constitute the majority of the population, have borne a  disproportionate share of the COVID burden. The ratio of the incidence of COVID cases to the population share of this age group, termed as the “impact ratio”, is much higher for India than in the countries compared.

Most of the countries exhibited a spike in the “impact ratio” for the age group above 60, while for India, the peak of the impact ratio is reached well within the working-age population group. This means that the average Indian in this age group is much more likely to be affected by COVID than citizens of countries compared in the paper.

The second important finding arises from an interesting exercise undertaken by the authors. They ask: how would these other countries have fared if their fatality rates had been applied to the age-specific COVID case distribution in India?

This adjusted CFR shows the Indian situation during the month of July to be much grimmer than in the countries compared. For instance, in The Netherlands, the unadjusted case fatality rate was 10 per cent, but which upon age-specific adjustment, turned out to be just about 2.2 per cent. Countries such as Spain or Switzerland also had much higher unadjusted CFR than India. In these cases too, after age-specific adjustments the CFR dramatically lowered to 2.1 and 1.2 per cent, respectively.

The aggregate case fatality rate in India, which at the first glance, appears flattering in comparison to other countries, upon closer examination reveals India in a much less flattering light once the aggregate is adjusted for the age distribution.

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A comparison with South Korea is illustrative in highlighting India’s poor relative performance.  In India, about three-fourths of all reported cases and a little less than half of all COVID related deaths have been reported among the age group of 20-59. South Korea provides a sharp contrast. In South Korea, 69 per cent of cases are reported among the same age group, which is comparable to India. However, COVID related deaths for this age group were only 7 per cent of the total COVID related deaths, compared to a whopping 45 per cent in India.

Shockingly, this demonstrates that the probability of an average COVID-infected working Indian dying is several times greater than for a South Korean in the same age group. Obviously, the much-touted demographic advantage has meant little to young Indians.

Lagged CFR raises more worries

The study also corrects the CFR measure for another reason, this one justified by the nature of the disease. Like all viral diseases COVID too has an incubation period before the infection takes hold of a patient. There is therefore a lag between the onset of the disease and when it manifests itself through a test, and when it results in fatality.

Thus, on any given date there would be a mismatch between the case count and the fatality count simply because the fatality for that date arises from a prior date and has no relation to the case count of that day. It thus makes sense to examine the fatality rate on a particular date in relation to the case count prevailing some days (typically 7-14 days) earlier. This is exactly what the study also does, by developing a “lagged” CFR, which is the ratio of the cumulative count of deaths on a particular date to the cumulative COVID case count on a date 10-14 days before.

Logically, this appears to be a more robust measure of CFR than the usual one, especially because it reflects the pattern of the disease.

The lagged CFR demonstrates that India’s performance, barring the Philippines and Colombia, is worse than most of the other countries compared. Even in Italy, where the unadjusted CFR was about 12 per cent, the highest in Europe, the 14-day lag-adjusted CFR during the month of July was better than India’s lag-adjusted CFR.

Using both 10 and 14-day lag, the study finds that at the end of July India’s CFR hovered between 3.1 to 3.6 per cent, while for most of the countries compared in Asia it was a little less than 3 per cent.

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Although there has been mounting anecdotal evidence since July that a large number of deaths did occur among younger sections of the population in India, it appears that this has been submerged in the low aggregate CFR story. The aggregated picture has thus blinded us to the much more worrisome scenario where the actual fatality rates do not reflect the demographic advantage the country is supposed to enjoy.

Those in power have used the low CFR as a shield, claiming that it provides evidence that their policy measures have worked. The paper by the three academics is a timely eye-opener, revealing a far grimmer picture of India in COVID times.

(The author is a researcher at the Economic Analysis Unit of the Indian Statistical Institute, Bangalore Centre)