Super-spreading, mobility and crowding

I still see quite a few journalists in India refer to “super-spreaders” vis-à-vis the novel coronavirus – implying that some individuals might be to blame for ‘seeding’ lots of new infections in the community – instead of accommodating the fact that simply breathing out a lot of viruses doesn’t suffice to infect tens or hundreds of others: you also need the social conditions that will enable all these viral particles to easily find human hosts.

In fact, going a step ahead, a super-spreading event can happen if there are no super-spreading individuals but there are enabling environmental conditions that do nothing to slow the virus’s transmission across different communities. These conditions include lack of basic amenities (or access to them) such as clean water, nutritious meals and physical space.

new study published by a group of researchers from the US adds to this view. According to their paper’s abstract, “Our model predicts higher infection rates among disadvantaged racial and socioeconomic groups solely from differences in mobility: we find that disadvantaged groups have not been able to reduce mobility as sharply, and that the POIs [points of interest] they visit are more crowded and therefore higher-risk.”

And what they suggest by way of amelioration – to reduce the maximum occupancy at each POI, like a restaurant – applies to a mobility-centric strategy the same way reducing inequality applies to a strategy centred on social justice. In effect, disadvantaged groups of people – which currently include people forced to live in slums, share toilets, ration water, etc. in India’s cities – should have access to the same quality of life that everyone else does at that point of time, including in the limited case of housing.

This study is also interesting because the authors’ model was composed with mobility data from 98 million cellphones – providing an empirical foundation that obviates the need for assumptions about how people move and where. In the early days of India’s COVID-19 epidemic, faulty assumptions on just this count gave rise to predictions about how the situation would evolve in different areas that in hindsight were found to be outlandish – and in some cases in ways that could have been anticipated.

Some modellers denoted people as dots on a screen and assumed that each dot would be able to move a certain distance before it ‘met’ another dot, as well as that all the dots would have a certain total area in which to move around. But as two mathematicians wrote for Politically Math in April this year, our cities look nothing like this:

According to this report, “India’s top 1% bag 73% of the country’s wealth”. Let us say, the physical space in our simulation represents not the ‘physical space’ in real terms, but the ‘space of opportunities’ that exist. In this specific situation of a country under complete lockdown because of the pandemic, this might mean who gets to order ‘contactless’ food online while being ‘quarantined’ at home, and who doesn’t. In our segregated simulation space therefore, the top chamber must occupy 73% of the total space, and the bottom chamber 27%. Also, 1% of the total number of dots occupy the airy top chamber, while the remaining 99% of the dots occupy the bottom chamber.

As a result, and notwithstanding any caveats about the data-taking exercises, researchers reported that Dharavi in Mumbai had a seroprevalence of more than 50% by late July while three wards in non-slum areas had a seroprevalence of only 16%.

The flawed models still can’t claim they could have been right if Mumbai’s slum and non-slum areas were treated as distinct entities. As T. Jacob John wrote for The Wire Science in October, one of the reasons (non-vaccine) herd immunity as a concept breaks when applied to humans is that humans are social animals, and their populations regularly mix such that ‘closed societies’ are rendered practically impossible.

So instead of mucking about with nationwide lockdowns and other restrictions that apply to entire populations at once, the state could simply do two things. First, in the short-term, prevent crowding in places where it’s likely to happen – including public toilets that residents of slums are forced to share, ration shops where beneficiaries of the PDS system are required to queue up, workplaces where workers are crammed too many to a room, etc.

Obviously, I don’t suggest that the government should have been aware of all these features of the epidemic’s progression in different areas from the beginning. But from the moment these issues became clear, and from the moment a government became able to reorient its COVID-19 response strategy but didn’t, it has effectively been in the dock.

This brings us to the second and longer term thing we should do: with the novel coronavirus’s transmission characteristics as a guide, we must refashion policies and strategies to reduce inequality and improve access to those resources required to suppress ‘super-spreading’ conditions at the same time.

The simultaneity is important. For example, simply increasing the average house size from 4 sq. m, say, to 8 sq. m won’t cut it. Instead, buildings have to be designed to allow ample ventilation (with fresh air) and access to sunlight (depending on its natural availability). As researchers from IDFC Institute, a think-tank in Mumbai, noted in another article:

Dharavi’s buildings and paths are irregularly laid out, with few straight routes. Based on calculations with OpenStreetMap routes and Google Earth imagery, it appears 68% of pathways and roads are less than 2 m wide. Such a dimension offers little space for air circulation, and reduces airflow relative to other, properly planned areas, and admits fewer air currents that could help break up the concentration of viral particles.

Mitigating such conditions could also impinge on India’s climate commitments. For example, with reference to our present time in history as the hottest on record, and many countries including India experiencing periods in which the ambient temperature in some regions exceeds thresholds deemed safe for human metabolism, science writer Leigh Phillips wrote for Jacobin that air-conditions must be a human right:

What would it mean to have a right to air-conditioning? Precisely, the right should be to have free or cheap, reliable access to the thermal conditions optimal for human metabolism (air temperatures of between 18 degrees C and 24 degrees C, according to the WHO). Neither too hot nor too cold. The right to Goldilocks’s porridge, if you will. New buildings must come with A/C as part of any “Green New Deal”. The aim of any programme of publicly subsidised mass retrofitting of old buildings shouldn’t be just to fuel-switch away from gas heating and improve insulation, but also to install quiet, efficient air-conditioning systems. At the scale of the electricity grid, this demand must also include the requirement that A/C run on cheap, clean electricity.

So really, none of what’s going on is simple – and when governments respond by offering solutions that assume the problem is simple are avoiding dealing with the real causes. For example, ‘super-spreading’ is neither a choice nor an event – it’s a condition – so solutions that address it as a choice or event are bound to fail. Seen the other way, a community with a high prevalence of a viral infection may be much less responsible for its predicament than the simple interaction of their social conditions with a highly contagious virus.

But this doesn’t mean no solution except a grand, city-scale one can be feasible either – only that all solutions must converge, by being targeted to that effect, on eliminating inequalities.

Vaccines for votes

A week or so ago, the Bharatiya Janata Party in Bihar released its poll manifesto, the first point on which was that should the party win, it would make a COVID-19 vaccine cleared by the ICMR available for free to every resident of the state. It was an unethical move, and Siddharth Varadarajan and I explained why.

Soon after, trolls on Twitter pointed out that Joe Biden had made the same promise ahead of the US presidential elections. And this morning, Indian Express quoted the Election Commission saying the BJP’s promise didn’t violate the poll code; the report also included a curious paragraph: that “the EC had taken the same stand on a complaint received during the Lok Sabha elections last year against the Congress’s NYAY scheme that guaranteed a minimum income of Rs 6,000 per month, or Rs 72,000 a year, for 25 crore people.”

The BJP’s promise still feels unethical to me. This isn’t for reasons that have anything to do with the poll code if only because the poll code’s scope doesn’t extend beyond the election itself, to the bigger picture.

At the outset, I don’t think vaccines should feature at all in election rhetoric (even if this may be wishful thinking with a majoritarian-populist government). But here we are.

The BJP is in power at the Centre – it runs the national government – and is hoping to come to power in the state. It isn’t necessarily including Nitish Kumar, the state’s incumbent chief minister and whose party the BJP is allied with, because the vaccine promise appeared only in the BJP’s manifesto, not in the alliance’s, and was announced with much fanfare by the Union finance minister. So Kumar was nowhere in the picture but the Centre was. This is a slight but significant difference vis-à-vis Biden’s promise.

State is a health subject in India but a COVID-19 vaccine, should one become available, will have significant participation by the Centre, from purchasing to distribution. Note that India’s states didn’t fight polio – they simply couldn’t. The country has a whole did and today COVID-19 presents an even bigger challenge.

A new study, echoing some older ones, has found that antibodies to COVID-19 fade over a few months. Assuming for a moment that vaccine-induced antibodies work like natural antibodies, and setting aside the fact that the question of antibody persistence is yet to be settled, access to vaccines (including the question of affordability) matters as much as its uniformity. That is, the level of access should be uniform across the epidemic’s ‘jurisdiction’.

For example, if a state with poor pubic health care and infrastructure to begin with is forced to administer the vaccine by itself, failures on its part could allow the virus to become endemic to that region, and allow it spread once again through the rest of the population once their antibody responses have weakened. So an additional pitfall here is if the BJP fragments the responsibility of distributing and administering a COVID-19 vaccine to the states, in an effort to legitimise piecemeal agreements based on political expediency, the vaccination drive will fail, especially in states like Bihar.

So while state governments will be able to decide whether to sell the vaccines for free, the decision depends considerably on the Centre’s cooperation. In effect, the BJP at the Centre abdicates the option to ensure everyone gets the vaccine at no cost when it offers to do so only in a specific area, and in exchange for votes.

Biden is not entirely in the clear either: ‘vaccines for votes’ is a prompt for voters to think of their choice of president as a question of life or death, which is nothing but a dire threat. But neither his case nor that of the Congress’s NYAY scheme are ones of abdicated responsibilities. Neither is yet in power in their respective countries, so neither is pulling back on their existing responsibilities, making their exercise contingent on electoral outcomes or vouchsafing the rewards to – from the epidemic’s PoV – an arbitrary section of the population.

Pandemic: A world-building exercise

First, there was light news of a vaccine against COVID-19 nearing the end of its phase 3 clinical trials with very promising results, accompanied with breezy speculations (often tied to the stock prices of a certain drug-maker) about how it’s going to end the pandemic in six months.

An Indian disease-transmission modeller – of the sort who often purport to be value-free ‘quants’ interested in solving mathematical puzzles that don’t impinge on the real world – reads about the vaccine and begins to tweak his models accordingly. Soon, he has a projection that shines bright in the dense gloom of bad news.

One day, as the world is surely hurtling towards a functional vaccine, it becomes known that some of the world’s richest countries – representing an eighth of the planet’s human population – have secreted more than half of the world’s supply of the vaccine.

Then, a poll finds that over half of all Americans wouldn’t trust a COVID-19 vaccine when it becomes available. The poll hasn’t been conducted in other countries.

A glut of companies around the world have invested heavily in various COVID-19 vaccine candidates, even as the latter are yet to complete phase 3 clinical trials. Should a candidate not clear its trial, a corresponding company could lose its investment without insurance or some form of underwriting by the corresponding government.

Taken together, these scenarios portend a significant delay between a vaccine successfully completing its clinical trials and becoming available to the population, and another delay between general availability and adoption.

The press glosses over these offsets, developing among its readers a distorted impression of the pandemic’s progression – an awkward blend of two images, really: one in which the richer countries are rapidly approaching herd immunity while, in the other, there is a shortage of vaccines.

Sooner or later, a right-wing commentator notices there is a commensurately increasing risk of these poorer countries ‘re-exporting’ the virus around the world. Politicians hear him and further stigmatise these countries, and build support for xenophobic and/or supremacist policies.

Meanwhile, the modeller notices the delays as well. When he revises his model, he finds that as governments relax lockdowns and reopen airports for international travel, differences in screening procedures in different countries could allow the case load to rise and fall around the world in waves – in effect ensuring the pandemic will take longer to end.

His new paper isn’t taken very seriously. It’s near the end of the pandemic, everyone has been told, and he’s being a buzzkill. (It’s also a preprint, and that, a senior scientist in government nearing his retirement remarks, “is all you need to know”.) Distrust of his results morphs slowly into a distrust towards scientists’ predictions, and becomes ground to dismiss most discomfiting findings.

The vaccine is finally available in middle- and low-income countries. But in India, this bigger picture plays out at smaller scales, like a fractal. Neither the modeller nor the head of state included the social realities of Indian society in their plans – but no one noticed because both had conducted science by press release.

As they scratch their heads, they also swat away at people at the outer limits of the country’s caste and class groups clutching at them in desperation. A migrant worker walks past unnoticed. One of them wonders if he needs to privatise healthcare more. The other is examining his paper for arithmetic mistakes.