When will the coronavirus pandemic come to an end? The question is on everyone’s mind, and while astrologers and politicians have answers, few scientists want to be drawn into hazarding a prediction.
According to Union Health Minister Harsh Vardhan’s recent remarks, the spread of coronavirus has already been contained in India because “half the total cases are from three states only and another 30 per cent from seven others.” But India has crossed two million Covid-19 positive cases and the graph continues to rise.
As Gina Kolata wrote in The New York Times earlier this year, medical historians recognise two types of endings. The medical ending, when the disease stops spreading; and the social ending, when people overcome their anxieties and move on. It would be appropriate to add a third type of ending: the political, when the government decides that as far as it is concerned, the pandemic is over. Any of these three endings could occur first, as political leaders and society can decide to move on regardless of whether the cases have peaked. If we look at the world today, it would not be overly cynical to conclude that politicians would rather move on, and that societies are distracted to such dysfunctional levels by social media-driven outrage cycles that they often ignore the extant pandemic. Maybe India is already at this point.
What about the medical ending? “It is impossible to put a date on it. If anyone tells you a date, they are staring into a crystal ball. The reality is that it will be with us forever because it has spread now,” Simon Clarke, a British cellular microbiologist offers the scientific establishment’s answer. Prudent and circumspect as this answer is, it is unsatisfying. It is hard for people to grapple with such an open-ended answer and is unhelpful for policymakers who need a base case to work on.
Vaccine has most answers
The conventional way to try to answer the question of ‘when new Covid-19 cases will start declining’ is to look towards the vaccine. Once a safe and effective vaccine has been discovered, trialled, manufactured and administered to a significant proportion of the population, society will acquire “herd immunity” against the SARS-CoV-19 virus, and the outbreak will be brought under control. It is estimated that 50 per cent to 75 per cent of the population will have to acquire immunity — either through infection or vaccination — for herd immunity to kick in.
How long will this take? Moncef Slaoui, one of the world’s foremost vaccine experts and chief advisor to the US government’s Operation Warp Speed project, is confident that up to 40 million at-risk people in the US will be vaccinated by February 2021. Goldman Sachs mirrors this confidence and expects the US drug regulator to approve at least one vaccine in 2020, and that “large shares of the US and European populations will be vaccinated” by June and September 2021, respectively. Vivek Murthy, former US surgeon-general, injects a degree of caution into these assessments, warning that the pandemic will not end before 2022. Russia plans to announce a vaccine this month, and China might do so by the end of the year, but it will be at least a year before we in India will receive those injections.
Vaccines might not offer permanent immunity, necessitating regular vaccination to keep Covid-19 at bay. Indian vaccine manufacturers are preparing to ramp up production, and as I’ve argued recently, Prime Minister Narendra Modi-led Union government must start planning the national vaccination campaign now, rather than later. If we are optimistic, we could say that India will have mass vaccination by late 2021.
Herd immunity hope, but without the vaccine
But remember that there’s another route to herd immunity — when enough people develop immunity to the virus by being exposed to it. Here’s a cynically optimistic back-of-the-envelope (COBOTE) calculation.
Let us assume India is undercounting Covid-19 positive cases. This is a reasonable assumption to make. Even a country like Switzerland estimates that “for every reported confirmed case, there were 11.6 infections in the community.” If we assume that India is undercounting at this order of magnitude, we have over 20 million positive cases in India today, doubling roughly every 20 days. If this holds, over 50 per cent of the population will have immunity by mid-November 2020, and the country will be at the threshold of herd immunity. The outbreak in Mumbai’s Dharavi area started slowing down when 40 per cent of its residents were infected.
This is good news. In fact, the more the undercounting, the faster we will hit the herd immunity threshold. Even if there is no undercounting, at the current doubling rate, half the country’s population will have immunity by Republic Day 2021.
There is, of course, bad news. Very bad news, in fact, for the case fatality rate is 2 per cent. That’s lower than in many other countries, but for India it still means a lot of deaths.
My COBOTE estimate is consistent with that of Bhaskaran Raman and his colleagues from IIT-Bombay who use Michael Levitt’s model to conclude that the pandemic in India will taper down by October 2020. Using the same model, but perhaps with different assumptions, my collaborator Karthik Shashidhar gives February 2021 as the date when the pandemic will ‘end’. Levitt’s model is pure “curve fitting” based on observations elsewhere. It doesn’t tell you why the cases will peak and decline. It could be due to my COBOTE reasoning. In any case, these estimates are much more optimistic than the “November ’21 or later” that a majority of the respondents to my Twitter poll felt.
Scientists are wise not to offer predictions on when the pandemic will end for there are too many factors at play. Mere analysts can take some liberties: I think some combination of infection and vaccination will cause the situation to improve by the end of 2021, perhaps as early as this November. The important thing, as I have argued before, is to be stoic about it.
The author is the director of the Takshashila Institution, an independent centre for research and education in public policy. Views are personal.
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