Pune | Updated: April 17, 2020 7:40:22 am
It could be a straw in the wind, possibly reflecting one consequence of the ongoing national lockdown. The daily growth in the number of COVID-19 positive cases across the country has been showing a declining trend over the last few days.
In fact, the compounded daily growth rate (CDGR) — a metric that factors in daily fluctuations and is, therefore, more representative of the trend — for the last five days has dropped to single digits, below 10 per cent, for the first time for any comparable period since the outbreak began in the first week of March.
By late Thursday night, the total number of positive cases reported from across the country was 13,328, according to data reported by states.
On April 11, this number was 8,408, which gives a CDGR of 9.65 per cent over five days. Since the first cases began to appear in March, the five-day CDGRs have ranged from 11 to 26 per cent.
Even over periods longer than five days, the CDGR has been higher than the present figure.
For example, between March 1 and March 24, when the lockdown came into force, the number of positive cases grew by an average of 25.1 per cent every day. Between March 1 and April 6, from which date a slight “flattening of the growth curve” had become noticeable, the numbers grew by an average of 22.7 per cent. From thereon, there has been a steady decline in CDGR.
In the 10 days since April 6, the positive cases have grown by an average of only 10.88 per cent every day.
Wednesday, April 15, showed a sharp dip in the daily number of positive cases. Only 862 positive cases were recorded on that date. In percentage terms, this was the lowest growth compared to the previous day in the last 20 days.
The 21-day lockdown, enforced from March 24 midnight, was intended to bring precisely this kind of slowdown in the spread of the disease. As reported by The Indian Express on April 13, the impact of the lockdown started to become evident from April 6. Scientists had then said that if the trend continued, the total number of infections could be well within 20,000 by April 20.
In the absence of any impact of the lockdown, this number could have jumped to at least 35,000.
Because a large proportion of the population has been confined to its homes, the number of transmissions of the virus per infected person has also gone down. This number, called the reproductive number or R-naught, is often used to measure how quickly an infectious disease is spreading. Before the lockdown, one particular group of scientists at the Institute of Mathematical Sciences in Chennai had calculated this number to be 1.83. This meant that every 100 infected people were spreading the disease to another 183. By April 12, the group said this number could be down to 1.55.
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