On April 9, we had published the growth curves of the novel coronavirus epidemic in various states. Covering data until April 7, we had showed how, just over a month after the outbreak began in the first week of March, the trajectory at the national level and in many states had begun to resemble what is so typical of the spread of an infectious disease — an exponential curve.
With less than a week to go before India steps out of a national lockdown, and into the next phase of the containment strategy, we revisit those growth curves here, in an attempt to illustrate the impact of the lockdown, or at least look at what happened during this period.
The national lockdown imposed at midnight of March 24 — often described as the biggest human quarantine ever — was aimed at slowing down the rate of growth of the epidemic, so that the number of patients needing urgent medical attention could remain at manageable levels while government and local authorities would ramp up health infrastructure and prepare themselves to deal with larger number of people at a later stage.
As we move towards the end of that period, the lockdown does seem to have resulted in a significant slowdown of the epidemic.
“I don’t think there is any doubt that the lockdown did manage to achieve a considerable slowdown in the growth of the disease,” said Sitabhra Sinha, a scientist at the Chennai-based Institute of Mathematical Sciences, who has been studying the spread of the epidemic in India through computer modelling.
Sinha had told The Indian Express on April 12 that, according to a study he had been carrying out with his colleague Soumya Easwaran, the number of confirmed infected cases was likely to remain below 20,000 by April 20. This, he had said, was a direct impact of the lockdown, in the absence of which, computer models showed, the number would have reached 35,000. The number on April 20 was 18,465, well within the prediction.
The reproduction number (R) we mention here —a reference to the average number of persons infected by an already infected person — are those calculated by Sinha’s team.
There has been a significant change in the growth curves of the states from the last time. Some states, such as Kerala, have done well to contain the epidemic, winning global acclaim for their efforts, while others, like Maharashtra and Delhi, have seen a steady rise in numbers.
Some other states, like Gujarat, which had a modest case load at that time, have emerged as fast-growing hotspots. And states such as West Bengal, Bihar and Jharkhand have just begun to show signs that they could potentially turn into trouble zones over the next few days, although their current case load is not very high.
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Editing: Kabir Firaque; Graphics: Mithun Chakraborty & Ritesh Kumar