Covid conundrum: Pandemic is hitting rich countries harder than poor ones

First word

THE New Yorker magazine published in its issue of March 1 a major investigative article titled “The Covid Conundrum.” It investigates the remarkable phenomenon that the coronavirus disease 2019 (Covid-19) pandemic is hitting some countries harder than others; and rich countries are faring worse than lowincome ones.

Siddhartha Mukherjee, a medical professional, carried out the research and wrote the 6,300-word report. It is perspicacious and most enlightening. I can only provide a partial summary here. You need stamina to read it in full.

Here are some excerpts from her article:

Epidemiological mystery

“After the pandemic was declared last March 2020, epidemiologists expected carnage in some areas. If the fatality rate from the ‘New York wave’ of the pandemic were extrapolated, between 3,000 and 5,000 people would be expected to die in Dharavi in India. Yet by mid-fall Dharavi had only a few hundred reported deaths — a tenth of what was expected — and the municipal government announced plans to pack up the field hospital there. By late December, reports of new deaths were infrequent.

I was struck by the contrast with my own hospital, in New York, where nurses and doctors were prepping ICUs for a second wave of the pandemic. In Los Angeles, emergency rooms were filled with stretchers, the corridors crammed with patients straining to breathe, while ambulances carrying patients circled outside hospitals.

And there lies an epidemiological mystery.

The usual trend of death from infectious diseases — malaria, typhoid, diphtheria, HIV — follows a dismal pattern. Lower-income countries are hardest hit, with high-income countries the least affected. But if you look at the pattern of Covid-19 deaths reported per capita — deaths, not infections — Belgium, Italy, Spain, the United States, and the United Kingdom are among the worst off. The reported death rate in India, which has 1.3 billion people and a rickety, ad-hoc public-health infrastructure, is roughly a tenth of what it is in the United States. In Nigeria, with a population of some 200 million, the reported death rate is less than a hundredth of the US rate. Rich countries, with sophisticated health-care systems, seem to have suffered the worst ravages of the infection. Death rates in poorer countries—particularly in South Asia and large swaths of sub-Saharan Africa — appear curiously low. (South Africa, which accounts for most of sub-Saharan Africa’s reported Covid-19 deaths, is an important exception.)

As the pandemic engulfed the world during the past several months, I kept returning to the question of what might explain these discrepancies. It was an epidemiological whodunnit. Was the ‘demographic structure’ of a population the real factor? Were the disparities exaggerated by under-counting, with shoddy reporting systems hiding the real toll from public-health analysts? Was government response a critical variable? Or were other, less obvious factors at play? Perhaps any analysis would prove premature. If new viral strains, such as the South African variant of the virus, known as 501Y.V2, were to sweep through Africa, every prediction of mortality might be overturned. But as I started speaking with colleagues from around the world I found that my puzzlement was widely shared. For many statisticians, virologists and public-health experts, the regional disparities in Covid-19 mortality represent the greatest conundrum of the pandemic.

‘However you might think of it, the mystery remains,’ Mushfiq Mobarak, an economist at Yale who has helped research Covid-19 response strategies for developing nations, told me. ‘Tenfold differences, or one-hundredfold differences — these aren’t minor. You have to account for other factors. You can’t just wave the numbers off. It’s going to be a lesson for this pandemic and for every future pandemic.’

So, if we were building a predictive model, we’d want to go beyond crude numbers, like median age, and get a more detailed picture of the socalled population pyramid. What’s the proportion of people between 70 and 80 in Senegal versus Spain? How does the population pyramid of Pakistan compare with that of Italy? Even a carefully drawn pyramid can tell us only so much. Mexico has a median age similar to India’s; the percentage of the population that’s over 65 is within a point or two of India’s. Yet India’s reported rate of Covid-19 deaths per capita is less than a tenth of Mexico’s.

Mobarak suspects that, in places like the United States, ‘the spatial distribution of the elderly’ probably also matters. Around a third of the deaths in the United States have occurred among residents and staff of long-term nursing homes. How do you assess the relative risks of the ‘warehoused elderly’ in the developed world and the ‘homebound elderly’ in the developing world, where 70- and 80-year-olds often live with a handful of younger family members? …

The task, then, is to factor in both intrinsic vulnerabilities (such as age or obesity) and extrinsic vulnerabilities (the structures of households, the levels of interpersonal contact). And here you start to get a sense of the challenges that our medical mathematicians must contend with.

The epidemiologists with whom I spoke agreed that these variables were the important ones to factor in. Accordingly, amid the spring surge, researchers at Imperial College London enlisted these variables in building models of Covid-19 mortality—with options for dialing up or down the level of interpersonal contact and viral contagiousness, and generating a range of possible outcomes.

Some governments responded more effectively

Could the mortality gap be a mirage? Politicians may have an incentive to minimize the crisis (although the matter of incentives is complex: countries like Ghana and Nigeria sought and received billions of dollars in foreign assistance to help them combat the virus). At the same time, Covid-19 can be stigmatized in poorer countries…

Oliver Watson, an epidemiologist at Imperial College London, who helped build the models, had a strong argument that systemic under-reporting was a factor…

The data problem could be worse in some countries, better in others. We’d expect that the amount of under-counting would vary from place to place because public-health resources vary, too.

Some epidemiologists argue that an accurate account of geographical disparities must give due weight to another extrinsic factor: certain governments have responded more effectively to the crisis than others.

Mohanan, the health economist who led the Karnataka study, agreed that, in some places, ‘decisive government action led to suppression of the pandemic.’

Other researchers are exploring whether acquired differences in human immunology might play a role. Acquired, or adaptive, immunity involves two principal kinds of cells: B cells make antibodies against pathogens, and T cells hunt for cells infected by a pathogen. B cells can be imagined as sharpshooters that target a virus with well-aimed bullets, while T cells are gumshoe detectives that go door to door, seeking viruses that are hidden inside cells.

Lesson in humility

The Covid-19 pandemic will teach us many lessons — about virological surveillance, immunology, vaccine development, and social policy, among other topics. One of the lessons concerns not just epidemiology but also epistemology: the theory of how we know what we know. Epidemiology isn’t physics. Human bodies are not Newtonian bodies.

Above all, what’s needed is humility in the face of an intricately evolving body of evidence. The pandemic could well drift or shift into something that defies our best efforts to model and characterize it. As Patrick Walker, of Imperial College London, stressed, ‘New strains will change the numbers and infectiousness even further.’ That quilt itself may change its shape.

Today, in Britain, the National Health Service, like many of its patients, is fighting for its life, overwhelmed by a new influx of Covid-19 patients, many of whom have the highly contagious B117 strain. In Nigeria, the reported per-capita mortality rate remains low by Western standards, but people remember that the president’s chief of staff — a father of four — succumbed to Covid-19, and watch as the nation’s health-care system continues to fray. Many officials are seeing a second wave decidedly worse than the first, as both the highly transmissible British variant and the South African one have started to crop up across the continent. Ghana recently suspended its parliament after an outbreak among members and staff. Throughout western, central, and eastern Africa, health officials hope that the mortality rates will stay relatively low, but know better than to assume that they will.”