If quarantining is not effective, the number can be 10 million; nationwide lockdown instituted now can help reduce impact
An ICMR study on containing the corona impact in big cities such as Delhi – done before the countrywide lockdown on Wednesday – suggests that in the best-case scenario, infections in the city could cross two lakh people, while in the worst-case scenario, due to higher passing on of infections, it could be as high as even 10 million.
The importance of the study is to show how critical lockdowns and quarantine are.
A ramp-up in testing for the novel coronavirus, along with the lockdown and effective quarantining – half the symptomatic cases are detected and quarantined within three days of the symptoms – could be a game changer. The flipside is that if the lockdown is violated and testing doesn’t increase fast enough – or if quarantining is ineffective due to the vastly overstretched health infrastructure – the numbers could go up rapidly, a point Prime Minister Narendra Modi kept emphasising on Wednesday.
The 10-million number in the worst-case scenario suggests the numbers put out by Ramanan Laxminarayan of the US-based Center for Disease Dynamics, Economics and Policy are not as outlandish as many have made out to be. Laxminarayan had estimated that 1 million people could eventually die in India while the number getting infected could be over 300 million.
The ICMR study, to be part of a special edition of the Indian Journal of Medical Research, chose Delhi along with Mumbai, Bengaluru and Kolkata as these are the big entry points for those coming from countries badly impacted by the pandemic.
ICMR has two models, an optimistic and a pessimistic one. In the optimistic model, one infected person infects 1.5 persons, while in the pessimistic model, the infection is passed on to four people. The peak infection comes 200 days after the onset in February in the optimistic scenario and within 50 days in the pessimistic scenario. In the optimistic scenario, the peak infected are 1.5 million and this rises to 10 million in the pessimistic scenario.
Researchers from ICMR and Imperial College, London, arrived at the projections, based on their mathematical modelling to study the feasibility of limiting local infections through screening of travellers from countries with Covid-19 countries and the extent to which a Covid-19 strategy could be limited by quarantining.
If, however, the Delhi and Central governments are able to take adequate action like quarantining, things can be quite different. The optimistic scenario for Delhi changes sharply, if an intervention in which 50% of the infected are quarantined within three days of exhibiting symptoms ? the total infections fall to 2,00,000, that, too, with the peak coming somewhere around 700 days from February.
For Mumbai, the optimistic scenario, with and without intervention, is 1,00,000 and 6,00,000, respectively. It is just under 1,00,000 and 5,00,000 for Kolkata and under 1,00,000 and 3,00,000 for Bengaluru.