Corona Daily 168: Epidemiological Whodunnit: Part Final

The third suspected reason for the low cases and deaths in Asia and Africa is underreporting. Are poor countries hiding the deaths? They are known to report only about 5% of Malaria deaths. Indian villages may be cremating people without reporting them. In Lusaka, Zambia; in an interesting experiment, postmortem was conducted on 364 people. Only five of them were tested for coronavirus when alive. The postmortem found 70 people had coronavirus.

Like in a murder investigation, one needs to look for a motive. Ghana and Nigeria received billions of dollars to fight the virus. Politically, they should be interested in over-reporting.

There are at least two ways to probe this issue. One is the all-cause mortality or excess mortality statistics. It is very difficult to hide bodies, even murderers can rarely do it successfully. Most civilized countries keep reliable death records. Natural deaths have a smooth, predictable graph. They don’t jump suddenly.

If you look at the excess deaths table by The Economist (till 18 Feb), other than South Africa, all countries are from Europe and America. Between 1 April- 31 Dec 2020, Russia reported 56,250 deaths. But excess deaths were 367,880 during the same period. Russia defines a covid death only if covid-19 is written as the cause on the death certificate. In the first ten months, USA reported 360,370 covid deaths, and 448,550 excess deaths. If there is under-reporting, it is universal, not just in poor countries.

The other way to judge if official trends are right is the empirical evidence. My doctor friends tell me the situation in Bombay hospitals is fine now. Last August, some hospitals were exclusively set aside for covid patients. This year, I have heard of new cases in my neighbourhood, but no deaths.

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The fourth factor is the government action and its willingness to enforce it. USA was an excellent example of what not to do. I believe at least half of the American deaths can be attributed to Trump’s recklessness and denial. In the best prepared nation, those deaths were avoidable. In rich nations, freedom of mind and expression, the ultimate test of democracy, was confused with liberty to ignore a health emergency.

Countries like Rwanda, on the other hand, were very clear with decisive control measures, strict curfew. And the Rwandan population listened. Now restrictions are lifted, and applied strictly only at a local level to suppress an outbreak.

Bombay’s Dharavi was another good example. Perseverant contact tracing, quarantine and disinfection measures managed to contain the virus in this supremely crowded giant slum.

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The fifth factor is the acquired differences in human immunity. The citizens of the poor countries believe their immunity is stronger.

B-cells and T-cells are part of acquired immunity. B cells make antibodies against viruses, T cells hunt for cells infected by a virus. Mukherjee compares B cells to a sharpshooter, and T cells to a detective. Some studies found that the novel coronavirus was triggering a T-cell response, based on a different infection earlier. The T-cell memory recognized this new foe, without meeting it earlier. In that sense, the novel coronavirus was not novel for everybody.

This cross-reactivity, the ability of immune system to protect against one pathogen based on another, appears to be stronger in Africa and Asia. A Mumbai doctor says in India people had really high levels of antibodies, the levels don’t decay even among old people, and the antibodies stay for a long time.

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Finally, the sixth hypothesis talks about the viral load. Indian cases have unusually low virus levels. Warm weather and open ventilation may be resulting in low-dose exposure. This hypothesis could also explain the large number of asymptomatic cases in India. Many serosurveys in Indian cities found more than half the population carrying antibodies.

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Mukherjee says it would be ideal to find a single cause, a single murderer for the murder. However, with so many hypotheses, he equates the case to Agatha Christie’s Murder on the Orient Express. Poirot realizes the murder to be a pre-planned collective act.

The strange matter of the coronavirus crippling rich nations may similarly be due to a combination of causes.

Ravi