Tag: herd immunity

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.

A 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.

Time and the pandemic

There is this idea in physics that the fundamental laws of nature apply the same way for processes moving both forwards and backwards in time. So you can’t actually measure the passage of time by studying these processes. Where does our sense of time, rather the passage of time, come from then? How do we get to tell that the past and future are two different things, and that time flows from the former to the latter?

We sense time because things change. Clock time is commonly understood to be a way to keep track of when and how often things change but in physics, time is not the master: change doesn’t arise because of time but time arises because of change. So time manifests in the laws of nature through things that change in time. One of the simplest such things is entropy. Specifically, the second law of thermodynamics states that as time moves forward, the entropy of an isolated system cannot decrease. Entropy thus describes an arrow of time.

This is precisely what the pandemic is refusing to do, at least as seen through windows set at the very back of a newsroom. Many reporters writing about the coronavirus may have the luxury of discovering change, and therefore the forward march of time itself, but for someone who is somewhat zoomed out – watching the proceedings from a distance, as it were – the pandemic has only suffused the news cycle with more and more copies of itself, like the causative virus itself.

It seems to me as if time has stilled. I have become numb to news about the virus, which I suspect is a coping mechanism, like a layer of armour inserted between a world relentlessly pelting me with bad news and my psyche itself. But the flip side of this protection is an inability to sense the passage of time as well as I was able before.

My senses are alert to mistakes of fact, as well as mostly of argument, that reporters make when reporting on the coronavirus, and of course to opportunities to improve sentence construction, structure, flow, etc. But otherwise, and thanks in fact to my limited engagement with this topic, it feels as if I wake up every morning, my fingers groaning at the prospect of typing the words “lockdown”, “coronavirus”, “COVID-19”, “herd immunity” and whatever else1. And since this is what I feel every morning, there is no sense of change. And without change, there is no time.

1. I mean no offence to those suffering the pandemic’s, and the lockdown’s, brutal health, economic, social, cultural and political consequences.

I would desperately like to lose my armour. The bad news will never stop coming but I would still like to get back to bad news that I got into journalism to cover, the bad news that I know what to do about… to how things were before, I suppose.

Oh, I’m aware of how illogical this line of introspection is, yet it persists! I believe one reason is that the pandemic is a passing cloud. It leapt out of the horizon and loomed suddenly over all of us, over the whole world; its pall is bleak but none of us doubts that it will also pass. The pandemic will end – everybody knows this, and this is perhaps also why the growing desperation for it to dissipate doesn’t feel misplaced, or unjustified. It is a cloud, and like all clouds, it must go away, and therefrom arises the frustration as well: if it can go away, why won’t it?

Is it true that everything that will last for a long time also build up over a long time? Climate change, for example, doesn’t – almost can’t – have a single onset event. It builds and builds all around us, its effects creeping up on us. With each passing day of inaction, there is even less that we can do than before to stop it; in fact, so many opportunities have been squandered or stolen by bad actors that all we have left to do is reduce consumption and lower carbon emissions. So with each passing day, the planet visits us with more reminders of how we have changed it, and in fact may never have it back to the way it once was.

Almost as if climate change happened so slowly, on the human scale at least, that it managed to weave itself into our sense of time, not casting a shadow on the clock as much as becoming a part of the clock itself. As humankind’s grandest challenge as yet, one that we may never fully surmount, climate change doesn’t arise because of time but time arises because of climate change. Perhaps speed and surprise is the sacrifice that time demands of that which aspires to longevity.

The pandemic, on the other hand, likely had a single onset… right? At least it seems so until you realise the pandemic is in fact the tip of the proverbial iceberg – the thing jutting above the waterline, better yet the tip of the volcano. There is a complicated mess brewing underground, and out of sight, to which we have all contributed. One day the volcano shoots up, plastering its surroundings with lava and shooting smoke and soot kilometres into the air. For a time, the skies are a nuclear-winter grey and the Sun is blotted out. To consider at this time that we could stave off all future eruptions by pouring tonnes of concrete into the smouldering caldera would be folly. The pandemic, like magma, like the truth itself, will out. So while the nimbuses of each pandemic may pass, all the storm’s ingredients will persist.

I really hope the world, and I do mean the world, will heed this lesson as the novel coronavirus’s most important, if only because our sense of time and our expectations of what the passage of time could bring need to encompass the things that cause pandemics as much as they have come to encompass the things that cause Earth’s climate to change. We’ve become used to thinking about this outbreak, and likely the ones before it, as transitory events that begin and end – but really, wrapped up in our unrelenting yearning for the pandemic to pass is a conviction that the virus is a short-lived, sublunary creature. But the virus is eternal, and so our response to it must also transform from the mortal to the immortal.

Then again, how I wish my mind submitted, that too just this once, to logic’s will sans resistance. No; it yearns still for the pandemic to end and for ‘normal’ to recommence, for time to flow as it once did, with the promise of bringing something new to the threshold of my consciousness every morning. I sense there is a line here between the long- and the short-term, between the individual and the collective, and ultimately between the decision to change myself and the decision to wait for others before I do.

I think, as usual, time will tell. Heh.