Why coronavirus didn’t hit India as hard as America and Europe

Why coronavirus didn’t hit India as hard as America and Europe

Most Diseases, From Diphtheria To Malaria, Affect Poorer Countries More Than The Rich. Why Is The Coronavirus Pandemic Different?

01.03.2021 

On Monday, Covid deaths in the US crossed the half-million mark. India had less than a third as many deaths despite a rickety health infrastructure and four times the population. Where Covid has felled elderly Americans in droves, here everybody knows neighbourhood uncles and aunties who recovered at home with only mild symptoms. It’s the same story across the developing world.

Why has Covid been kinder to India, Pakistan, Bangladesh, and almost the entire Africa? It’s an “epidemiological mystery,” Siddhartha Mukherjee, cancer specialist and author of the bestselling ‘The Emperor of All Maladies’ writes in a recent New Yorker article.

The possibilities are many, and Mukherjee investigates some at length before concluding that if this were a murder mystery, it would not have a “one murder, one murderer, one weapon” plot. Here’s a look at three of the key suspects.

Younger population

Covid’s severity increases with old age. “After the age of 30, your chance of dying if you get Covid-19 doubles roughly every eight years,” says Mukherkee. So, countries with an older population – Belgium, Italy, the US and UK, for example – are bound to be disproportionately hit by it.

In contrast, poorer countries have a younger population overall. India’s median age (the middle value of all ages) is 28; Italy’s is 47. It’s easy to see which country will have more Covid deaths for every million people. And age is the most common explanation for Covid’s varying impact between rich and poor nations.

Mystery solved? Mukherjee points out that the median ages of Mexico (29) and India are roughly the same. The share of population older than 65 is also similar. “Yet India’s reported rate of Covid-19 deaths per capita is less than a tenth of Mexico’s.”

Immune system’s T cells

Street wisdom says Indians don’t need to fear Covid because our immune systems are not wimps. Filth, street food, flies, dengue, malaria – we are attuned to all of them.

Mukherjee looks at immunity from a scientific angle. There are three main players in it: antibodies, B cells and T cells. Antibodies cannot explain our better response to SARS-CoV-2 – the novel or new coronavirus – because they are custom-made for each germ. Because the coronavirus is new, there is no possibility of having antibodies for it without exposure.

As for B cells, their job is to make antibodies. That leaves us with T cells. When scientists at California’s La Jolla Institute for Immunology tested blood plasma samples collected before the pandemic, they found that in 40% of the samples, “the new coronavirus was somehow triggering a T-cell response.”

What exactly are T cells? They are immune system cells that “hunt for cells infected by a pathogen.” When a virus infects you, it starts turning your cells into factories to make copies of itself. T cells blow up these virus factories.

That does not explain how T cells can recognise a brand-new virus. Mukherjee says it’s because they target germs on the basis of resemblance, not a perfect photo match (unlike antibodies). Why does the new coronavirus look familiar to T cells? It’s because there are four other coronaviruses – called OC43, 229E, NL63 and HKU1 – that cause common colds. Everybody’s been infected by one or more of them. Research at Seattle Pacific University shows all coronaviruses – new and old – have many common building blocks that can trigger T-cell action. At Boston University, scientists found that Covid patients who had a cold between 2015 and March 2020, had “lower rates of mechanical ventilation, fewer ICU admissions, and significantly fewer deaths.”

Undercounting

Can it be that poorer countries are underreporting Covid deaths? Zambia has officially reported only 1,040 Covid deaths so far, but postmortems of 364 bodies in its capital Lusaka found the coronavirus in 70. Roughly one in five dead was infected. Analysis of household surveys that are done every four months in India also showed “deaths doubled between May and August” last year, but a deeper examination revealed the deceased were often younger people in rural areas. Not exactly the typical Covid fatality profile.

Actual deaths are higher

A study published in the British Medical Journal last month suggested that case fatality ratio (CFR) – deaths among total cases – can miss deaths of those who were never tested for Covid-19 but were hospitalised for complications stemming from infection. State-wise analysis shows the “corrected” CFR, which adjusts for testing failures, can be much higher than the reported CFR

Wrong predictions

Mathematical models give health authorities an idea of how much a disease will spread, and how much damage it will cause. For Covid, these models have been largely correct for rich countries, but off by a “staggering margin” when it comes to developing countries.