SARS-CoV-2 presents several mysteries. A disease of such scale and severity is expected to affect the poorest countries most. They have the worst doctor-patient ratios, poor public health infrastructure, high pollution levels. What has happened during the pandemic has baffled even the experts.
North America with 7% of the global population
accounts for 30% of the cases and deaths. Same with Europe. Asia with 60% of
the world population suffered only 15% deaths, and the African continent less
than 4%. Dharavi, Asia’s largest slum, experienced only one tenth of the
expected deaths. It hasn’t had any since December. On the other hand, Los Angeles
has no spare ICU bed.
Malaria, Typhoid, Diphtheria and AIDS, as a rule, hit
the poorest countries. Deaths per million is possibly the best measure for comparison.
The top countries include Belgium, UK, Italy, Portugal and USA, each of them
having lost more than 1500 people per million. India’s death rate is ten times
lower. Nigeria’s is one hundredth that of the USA.
Some diseases are called rich man’s diseases. Covid is
not that, because lots of poor people in rich countries have died. But I won’t
hesitate to call it a ‘rich nation’s disease’.
What is the cause of this mystery? This week Siddhartha
Mukherjee, in an excellent article in the New Yorker discusses this.
Mukherjee is the Pulitzer winner for his book “The emperor of all maladies:
a biography of cancer.” I will cover the key points from his article over today
and tomorrow.
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First factor
is the median age. Please note all the factors are hypotheses at this
stage. They suggest rather than prove anything.
In India, the median age is 28, in USA 38, UK 40.
Italy at 47, Germany 48, and Japan 48 are some of the oldest countries. Nigeria’s
median age is 18. Most African countries are very young.
Virologists and number crunchers have stated a rule of
thumb: After thirty, the chance of dying with covid-19 doubles every eight
years. (No need to apply the rule to yourself, can be depressing). If true, it
is only logical that countries with a high number of elderly residents will
suffer the most covid casualties. Good so far. However, questions remain. For
example, Mexico’s median age is like India’s. But it has lost ten times more
people to covid.
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The second possible factor is the family
composition. Who lives with whom and the human interaction. Usually, the
richer the country, smaller is the size of the household. In UK, the average
household size is 2.3, in Africa’s Benin 5.2. However, in the context of the
pandemic, this statistic can be deceptive. In the UK and USA, a large number of
elderly people live in long-term nursing homes. In fact, around one third of
the covid deaths in the USA happened in care homes. The question then is
whether an Indian or African living in a three-generation household is more at risk
than the 80+ Americans or British living together in a nursing home?
Covid vulnerabilities are of two types: intrinsic (age,
obesity), or extrinsic (household size, medical professional). In the morbid trade-off
question, one wonders if it is better to be young in a crowded house, or old in
a large house?
The statistical models base their forecasts by answering
such questions. Epidemiologists were brilliant in forecasting deaths in the rich
world. In the USA, the actuals almost match the projections. But the models
went abysmally wrong in the poor world. As per the model, Pakistan was expected
to have 650,000 deaths so far, they have had 12,000. Cote d’Ivoire lost fewer
than 200, instead of the projected 52,000. Epidemiologists, last March, were
certain Nigeria would suffer 418,000 deaths in a year’s time. Nigeria lost
1300, and most cases are mild.
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(Continued tomorrow)
Ravi