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Sunday, June 20, 2021

Explained: Where does virus go from here?

A look at various possible scenarios that can happen in the COVID-19 outbreak, which one of these is most likely playing out in India now, and the role of the lockdown in addressing the situation.

Written by Amitabh Sinha
Pune | Updated: April 2, 2020 2:54:46 pm
India coronavirus lockdown: Where does virus go from here? India coronavirus lockdown: Migrant workers rush to enter a bus leaving Allahabad on Sunday. (Express Photo: Ritesh Shukla)

On Sunday, the number of people infected with the novel coronavirus in India crossed the 1,000 mark. There are 40 countries who have more people infected. The death toll in India reached 27; the count is higher in 30 other countries.

These numbers would suggest that India is in a relatively better, even if still difficult, situation. But this is not so simple. There are scientists who are saying that over the next two months, the number of infected people in India could cross a million. There are others who assert that community transmission of the virus must already be happening, and these are not getting captured because India has not been testing enough number of people. The Indian Council of Medical Research (ICMR) has been maintaining that despite the emergence of a few cases for which the original source of infection has not been traced, there is no community transmission happening.

Then, there are research papers suggesting that the survivability of the virus weakens in high temperatures, and some have used this to explain the relatively low infection rate in India. In the midst of all this, an unexpected humanitarian crisis in the form of desperate movement of migrant labourers threatens to undo the benefits of the largest-ever lockdown imposed anywhere in the world.

The Indian Express spoke to several scientists and experts to understand how these disparate, some of them conflicting, elements explain the current health crisis. The picture that emerges is still not complete, but it does indicate how these elements are joined together. And this is how it looks like.

The possible pathways

Let’s begin with the most important question: How will this end? When a new virus outbreak happens, there are three predictable scenarios through which its spread can be contained.

BLOCK AT SOURCE: In this scenario, every source of the transmission is isolated. In the context of the spread in India, for example, this would have meant identifying and isolating every incoming foreign traveller carrying the virus to ensure that they did not pass on the infection. It is almost certain that this has not happened. Otherwise, the daily detection of new positive cases would have at least slowed down, if not stopped, a week after all incoming flights were stopped. That has not been the case.

COMMUNITY TRANSMISSION: This when the virus gets into the community and infects a substantial fraction of the population. The more vulnerable in the population die of the infection. But in the process, the population develops an immunity to the virus, after which the infections slow down, and eventually the virus is rendered ineffective. This is the principle of herd immunity. This situation becomes more or less inevitable once community transmission begins. The size of the population that gets infected before immunity is developed depends on many factors, notably on how fast the disease is spreading (how many people are infected on an average by every infected person). This entire process can normally take six months to a year. As of now, scientists do not know how long this period could be in case of SARS-CoV2. In any case, this process can be very painful, depending on how lethal the virus is.

India coronavirus lockdown: Where does virus go from here? India coronavirus lockdown: Policemen distribute water and food packets to migrant workers waiting for buses at Transport Nagar in Jaipur. (Express Photo: Rohit Jain Paras)

VACCINE: This is the situation in which a vaccine is developed, and administered to every vulnerable person. By all accounts, we are at least 12-18 months away from developing a vaccine for SARS-CoV2. By that time, the herd immunity scenario would have played itself out.

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Two more possibilities

Theoretically, there could be two other scenarios as well.

VIRUS FAILS TO SURVIVE: This arises when, due to some reason, possibly unsuitable climatic conditions, the virus is not able to survive long enough in a geographical region, thus losing its potency to infect large numbers. Some scientific research has indicated a vulnerability of this virus in high temperatures, but the evidence is not yet conclusive. On the other hand, the fact that the virus has survived in India for more than a month, and continues to infect a large number, could be offered as a counter-argument.

PRE-EXISTING IMMUNITY: This could happen if the population has a pre-existing immunity to the virus. In the case of SARS-CoV2, there is no evidence to suggest that the Indian population has any special pre-existing immunity, even though the rate of spread of the virus has been slower in India than many other places.

The one most plausible

Most scientists agree that SARS-CoV2 would follow the second scenario in India — community transmission leading to possible eventual immunity. Although there are very few recorded cases of community transmission as of now, and even these are contested, scientists see this scenario as far more likely than any of the other scenarios. The ICMR has acknowledged that there have been a few cases in which the original point of transmission has not been ascertained, but has insisted these numbers are so few that they do not establish community transmission.

Scientists saying that community transmission must be happening are not relying on any data (there is hardly any worth a note from India as of now) but on their knowledge of how such diseases spread.

But if that scenario is indeed playing out, at some point of time, the spread could be rapid. If no intervention is made to halt the spread, infections would grow at an exponential rate, and very soon a large proportion of the population would get infected. This would be in accordance with the projections made by several scientific groups using mathematical models. Such projections are based on a number of assumptions, including the kind of interventions being made, their likely impact, and the expected behavioural responses of the general public to these interventions.

Also read | Recovered COVID-19 patients’ plasma: what is this experimental therapy?

Once a substantial proportion of the population gets infected (and most of them recover), herd immunity will kick in and fight back, slowing down the infection rate. In the olden days, this is how most disease outbreaks used to unfold. The death toll in these outbreaks would depend on the nature of the virus. If the virus is not very lethal, an argument can be made to let the virus spread in the community and herd immunity develop, though what constitutes an acceptable death rate can be an extremely sensitive issue.

India coronavirus lockdown: Where does virus go from here? India coronavirus lockdown: People and their belongings being sprayed with disinfectants at Anand Vihar bus terminal. (Express Photo: Prem Nath Pandey)

Reasons to be cautious

There are two reasons why governments would be extremely reluctant to take this approach to deal with the outbreak. In today’s world, letting the virus spread and take its toll would be “considered extremely unethical”, as Vineeta Bal, an immunologist at the Indian Institute of Science Education and Research, Pune, put it. No government can afford to be seen to be doing nothing against a disease that is claiming lives, even if whatever it decides to do might not alter the final death toll very significantly.

The second reason concerns practical difficulties. A very small proportion of infected people, about 5-7%, require hospital care. But if the virus is allowed to spread rapidly in a country like India, that 5-7% would translate into huge numbers, beyond what its medical infrastructure could handle.

This is where the utility of the 21-day lockdown, and other measures taken before that, kick in.

How lockdown helps

By confining a majority of the population to their houses, and limiting their contact with other people, the spread of the virus can be significantly slowed down. It cannot be entirely stopped because there always would be some people – emergency workers, healthcare professionals, and those involved in essential duties — who would continue to interact. Additionally, in this vast country, some people are always likely to flout lockdown instructions and continue mingling with others. Even if a very small proportion of these people are carrying the virus, it would continue to find new susceptible hosts and remain in circulation.

A slowdown in the infection rate due to measures like lockdown would also reduce the pace at which herd immunity is built. But most importantly, it would give authorities the time needed to ramp up medical capabilities, create emergency infrastructure, and prepare itself to deal with large influx of patients who would inevitably arrive.

“Achieving an optimum balance between these two objectives can be very difficult,” says Bal.

India coronavirus lockdown: Where does virus go from here? India coronavirus lockdown: A deserted Srinagar street on Sunday amid the nationwide coronavirus-induced lockdown. (Express Photo: Shuaib Masoodi)

To be successful, the lockdown expects a mature response from both the general public as well as government authorities. By following instructions on remaining confined and social distancing, the public has to make sure that there is no run on the hospital beds, ICUs and ventilators. And the government has to ensure that it uses this period to significantly ramp up its capacities. This is already happening. Several cities and states have started earmarking a certain number of beds for COVID-19 patients. Isolation wards are being created in trains. There are plans to convert large public areas like stadiums into makeshift hospitals dedicated to COVID-19 patients. Medical equipment are being ordered in large numbers.

Also read | An Expert Explains: ‘Coronavirus will stay; difficult to lock down for long’

The other consequence

By shutting down railways, airlines and bus services, the government probably thought it will keep people where they are. What it did not probably factor in is that people would walk hundreds of kilometres to reach their homes. Besides the pain it has caused to individuals, and beyond the humanitarian crisis that it has become, such largescale movement also seriously undermines the purpose of the lockdown.

A large majority of migrant workers, who are desperately trying to reach their homes, are driven by fear – the fear of a ‘city disease’ from which they will be safe only in their native places, the fear of becoming socially isolated in a place which is not their own. Many of them have been saying that if they have to die, they would much rather die in the company of their family and village community.

Better communication could have eased the suffering. The fears need to be addressed, not just in those who are desperately walking, but also among those who are getting increasingly paranoid in their homes, fearing they would get infected and die. All these people need to be reassured, ideally from high levels of government, that even if they get infected, most of them were likely to recover without major problems, without needing hospitalisation.

Here’s a quick Coronavirus guide from Express Explained to keep you updated: What can cause a COVID-19 patient to relapse after recovery? | COVID-19 lockdown has cleaned up the air, but this may not be good news. Here’s why | Can alternative medicine work against the coronavirus? | A five-minute test for COVID-19 has been readied, India may get it too | How India is building up defence during lockdown | Why only a fraction of those with coronavirus suffer acutely | How do healthcare workers protect themselves from getting infected? | What does it take to set up isolation wards?

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