On 4 June, the Indian Institute of Science (IISc) and the Tata Institute of Fundamental Research (TIFR) released a paper detailing a mathematical model that suggested strategies to ease lockdown restrictions in Mumbai.
Their suggestions, based on the model, were two-fold.
- Mumbai could begin a phased reopening of workplaces, with 20-30% attendance, without overwhelming the city’s medical capacity.
- The city’s local trains—used by 7.5 million people every day pre-Covid—could resume with 20% capacity, provided people maintained social distancing and wore masks.
On 15 June, Mumbai resumed its train services after almost three months, limiting their use to essential service workers.
Unlike earlier Covid-19 models, the IISc-TIFR version does not focus on predicting the number of cases or fatalities. Instead, it compares various scenarios and suggests the best option going forward.
Compare this to one of the earliest models, which came out on 24 March— the day India’s first 21-day lockdown was announced. The model, by researchers from the Center for Disease Dynamics, Economics & Policy (CDDEP), Johns Hopkins University, and Princeton University, forecast the spread of Covid-19 in India.
In the best case, it said, there would be more than 125 million infections by mid-May. In the worst case, 250 million in April. Today, in July, India has 5,85,792 total recorded cases. The huge difference, according to Ramanan Laxminarayan, founder and director of CDDEP, is due to India’s low testing rates coupled with the nationwide lockdown that was imposed soon after the study was published. Moreover, according to Laxminarayan, the actual number of infections till date, according to Indian Council for Medical Research’s (ICMR) serological survey serological survey Serological survey A serological survey looks for antibodies in a population in order to estimate the prevalence of a disease. was between 5 and 10 million, based on their 0.73% seropositivity rate. “We have 500,000 reported cases today and it is reasonable that we have between 50 million and 100 million infections already,” Laxminarayan said in an emailed response.*
The utility of models does not come from their numbers, said Gautam Menon, professor of physics and biology at Ashoka University. Menon was part of a group called the Indian Scientists’ Response to Covid-19 (ISRC), which developed its own model for the spread of the disease in India. The group comprises more than 500 scientists, engineers, and technologists.
“You need models at every stage. How many ICUs and ventilators do you need? Those early models were important to give you a sense of the scale of what you needed to do. The numbers are not to be taken seriously,” added Menon.
However, the numbers were taken seriously. India shut its economy and went into lockdown sooner than sooner than The Wire COVID-19: What Did India Gain From the Nationwide Lockdown?