In late January, the United Kingdom was busy with Brexit, the United States was busy following (or ignoring) the impeachment trial of President Donald Trump, and many in India were busy protesting the Citizenship Amendment Act. In late February, while we were trying to comprehend the horrors of the Delhi riots, US diplomats and Taliban leaders were working towards a treaty to end the war in Afghanistan, and the top civil servant in the British Home Ministry was resigning to protest against what he described as the Home Secretary’s bullying.

Then in March, Covid-19 engulfed our world and upended it.

On March 23, Italy, Spain, the UK, and the US were in lockdown, and many Indians, having obeyed Prime Minister Narendra Modi’s call to observe a “janata curfew”, or people’s curfew, were clanging pots and pans to scare away the novel coronavirus.

The pandemic raging over the last couple of months has brought mankind to its knees, causing loss of lives and of livelihoods, as also deep social and psychological stresses. How will this end? How are we going to survive it?

Sitting in the middle of Covid-19, these questions are almost unanswerable. But at this time, different parts of the world seem to be located in different phases of the pandemic cycle. The horrific disease surge that befell Italy and Spain in March and in early April has subsided. But in South Asia and in Africa, the worst might be yet to come. What clues do the experiences of some of the West’s most affected cities provide regarding our own chances of survival?

Comparing surges

New York and Madrid have suffered greatly in the pandemic, with confirmed cases totaling 130,000 in the US city and 55,000 in the Spanish one. In India, Mumbai and Delhi have been the most affected cities till date, with about 7,600 and 3,700 cases until Saturday.

How does one compare the Covid surges across these very different cities, given that testing rates across countries have varied so much – from less than 2 tests per 10,000 people in India to more than 30 tests per 10,000 people in the US?

One way is to focus on the “daily growth rates of new infections” rather than the “daily infection numbers”, assuming that the relative testing rates across countries have remained reasonably stable over time.

Using publicly available data from city governments and from, I carry out that exercise to contrast the experiences of these four cities over the months of March and April, taking the date on which a city’s cumulated disease-load crossed 30 to be its start date. The following charts show the graphs of daily disease growth rates in New York and Delhi and in Madrid and Mumbai.

The graphs for New York and Madrid tell the following story. The cities have been subjected to a sequence of disease-growth surges, rather than a single big surge. The initial surges have been intense, but there has been a final surge after which daily disease growth rates have slowly subsided.

I identify the date of the last big surge – when the daily disease growth rate crossed 30% for the final time – to be a city’s “turn-around date”.

In New York and Madrid, the intensity of the Covid-19 attack reached its peak quite quickly, and then subsided slowly over a longer period of time – the turn-around happened in 12 days time. But after that, it has taken about a month for the daily disease growth rate to fall to 1%.

The nature of the Covid-19 surges have been remarkably similar for New York and Madrid (and also for Paris, Milan, and London, for which I have constructed similar graphs). This, in spite of the underlying heterogeneity of the cities – especially with respect to population density (New York has much greater density than the other cities), and the distinct lockdown strategies that the different cities have pursued. It is indeed heartening to note that in these places, the disease growth surges have decisively lost their sting and their volatility over time.

Indian situation

Sitting in India, can we draw hope from the experiences of these First World cities? In contrast, how have our own worst-affected cities fared?

The Covid-19 surges have occurred later in the Indian cities, after the country was locked down. Nevertheless, the graph for Delhi is not very dissimilar to that of New York: Delhi has also suffered several disease growth surges, with steeper surges early on.

There are, however, two noteworthy differences. The turn-around date has arrived later in Delhi (19 days after the start date), and beyond that date, the growth-surges have not subsided steadily – there have been recent upticks in disease growth rates.

The experience of Mumbai reinforces these concerns. Not only has there been quite a few surges after the (assumed) turn-around date, but following six days of steady decline thereafter, the city is suffering a recent continuing and significant increase in daily disease growth.

Will Mumbai face another Covid-19 surge in the near future? Some think yes.

It is possible that India’s lockdown has blunted the sharpest of the Covid-19 attacks that we have faced – the highest daily disease growth-rate has not gone beyond 95% in any India city (as it has in New York and Madrid). However, while one can reasonably predict that New York and Madrid (as well as Paris, Milan, and London) are out of the woods by now, the same cannot be said for our cities.

Of course, a part of the reason is that the disease surges started much later in India, especially in cities like Ahmedabad and Indore where the current disease growth rate is significant. But the worry is that in dampening the intensity of the disease growth surges, India might have also prolonged the possibility of their recurrence.

Arijit Sen is a professor of economics at the Indian Institute of Management Calcutta. Views are personal.