With India recording a first-time-ever three-digit rise in the confirmed cases of COVID-19 in the past 24 hours, the Health Ministry on Saturday said that had a lockdown not been imposed, the country would have been staring at least 8,00,000 cases by April 15. The Ministry reported over 7,200 cases on Saturday.
The Indian Council of Medical Research (ICMR) — the technical arm of the Ministry that is overseeing testing and epidemiology — was not involved in preparing this estimate, Lav Agrawal, spokesperson of the Ministry, said at the daily media briefing.
He displayed a graph that showed three curves: One a red curve, denoting neither lockdown nor containment in place, that steeply rose to 2,08,544 cases on April 9 (and with a note that it would extend to 8.2 lakh by April 15); a blue, gentler curve that rose to 45,370 by April 11 (and 1.2 lakh cases by April 15), the blue indicating the situation with “containment measures but no lockdown”; and the final green line indicating the 7,447 cases at present.
“Lockdown and containment measures are important to fight COVID-19. If we had not taken any measures, we might have had 2 lakh cases at this time (April 11),” Mr. Agrawal added. There were no further details available of how the projected figures were arrived at.
Determining the rate of spread of infectious disease is different from extrapolating a given number of cases at an initial point and assuming a particular rate of growth and plugging it into an exponential mathematical equation, experts told The Hindu .
“From just this graph alone, it isn’t possible to work backward and figure out the assumption used by the modeller to arrive at the (2,00,000) figures. The curves assume a constant rate of growth, which is not what we’ve seen how the cases increase in India, or anywhere else in the world,” Aritra Das, a medical doctor with a doctorate in epidemiology, who consults with IQVIA. “Estimating the growth in cases requires knowing an R0 [reproduction number that denotes how many an infected person will further infect] and that can’t be derived from what we now have.”
A study in February, which was publicised on March 23, remains the only actual modelling study involving ICMR epidemiologists and international experts in the field. That study didn’t estimate numbers but — based on the state of affairs in February — recommended that India should have focussed on finding transmission in the community and quarantining instead of “border control” because of the large uncertainty in detecting asymptomatic travellers harbouring the infection and becoming spreaders.
Another ICMR study published this week found that 40% of those with severe respiratory illnesses sampled and detected with COVID-19 could not have their contact history established.
The ICMR said 1,71,718 samples were tested, including 16,564 in the last 24 hours.
The government said it was containing the wide spread of the disease by establishing containment zones. For instance, in Agra, when the first case was isolated, a 3-kilometre zone was considered a ‘containment zone’ and a 5-kilometre zone was a further buffer zone where the movement was regulated and suspects were traced, quarantined and isolated.