Mumbai: Since the past week, Mumbai has been seeing just 400 to 600 new Covid-19 positive cases as against over 2,000 at one point in October last year. Similarly, daily Covid fatalities are now contained in single digits.
For a city that was once India’s most dreaded Covid hotspot, the stabilising of cases comes as a huge relief. But, for a group of scientists at the Tata Institute of Fundamental Research (TIFR) and Indian Institute of Science (IISc), this development does not come as a surprise at all.
These scientists, through a simulation model, had predicted this weakening of the Covid wave in Mumbai and helped the city’s civic body with specific recommendations to work towards this scenario.
These inputs helped the Brihanmumbai Municipal Corporation (BMC) take informed policy decisions regarding its own data, healthcare infrastructure, and how and when to open up the city.
The Covid projection model
The first Covid-positive case in India was reported in Kerala on 30 January 2020. Mumbai recorded its first case on 11 March.
It was around this time that researchers in the TIFR and IISc decided to develop a simulation model to anticipate the spread of Covid in India, inspired by similar models in the West, such as the one developed by epidemiologist Neil Ferguson at the Imperial College of London.
“We decided that we should also have a similar simulation model. These were joint efforts by IISc and TIFR where we made a simulation model and made projections for Bengaluru and Mumbai. We shared our reports with government officials as well as the general public,” said Dr Sandeep Juneja, dean of the school of technology and computer science at TIFR.
The simulator mimicked various interaction spaces such as households, schools, workplaces and took into account factors such as population densities, age distribution, household sizes to assess the impact of various non-pharmaceutical or regulatory interventions on the progression of Covid in the city.
Later, factors such as the impact of intermingling during festivals, such as Ganpati that led to a spike in Covid cases, and serological survey results were also taken into consideration for the simulation.
“We set the expectations for the city through our reports in which we said that November onwards, the cases will decline and by January the epidemic in Mumbai will be largely under control. Our input was one of the many that the BMC received, it helped set a direction for the city,” Juneja said.
Additional Municipal Commissioner Ashwini Bhide, who regularly interacted with the TIFR team, said the scientists were part of the Covid resource group headed by the Wadhwani Institute of Artificial Intelligence, and were advising the BMC in sharpening its data as well as taking policy decisions.
“We were getting projections from two sources, one was from this Covid resource group and the other was from Fractal Analytics, an artificial intelligence company. They were helping us till almost Diwali. Both these inputs were helpful in taking policy decisions. They would generate weekly reports. We used to have Zoom presentations,” he added.
“They would also point out any gaps in our data to improve the quality of data that we use. For example, there were duplicate addresses, names etc. We changed the entry fields accordingly and made giving pin code mandatory. All this also helped us get ward-wise information,” Bhide added.
Two reports with recommendations
Other than the Covid projection simulator, TIFR scientists also worked with the BMC and NITI Aayog on conducting two serological surveys in Mumbai.
The first survey, the results of which were released in July, found 57 per cent of the samples from slums and 16 per cent from non-slums had Covid-19 antibodies. The second survey, released in October, showed 45 per cent people in slums had Covid antibodies, while the infection had spread more in cities, non-slum areas with 18 per cent seroprevalence in the latter.
The results of these too helped the TIFR-IISc team sharpen their projections for the spread of the virus in Mumbai.
Based on the simulation model, TIFR scientists Prahladha Harsha, Ramprasad Saptharishi and Juneja submitted a report of broad recommendations to the BMC in September. This was updated in October.
Both reports, accessed by ThePrint, acknowledged that opening up of Mumbai is linked to its congested public transport systems, especially the local trains. Opening up the city too swiftly may lead to a sudden increase in the spread of the epidemic “leading to difficulties in managing a second wave of hospitalisations”.
The reports, however, advocated that the impact of fully opening up the city on 1 November is manageable with the existing medical infrastructure.
“Given the large amount of suffering that results from a lockdown, and the high Covid positivity in Mumbai as projected by our model that crucially relied on the data from the Mumbai sero survey, we had recommended a more aggressive schedule for opening up, but the government has decided to take a more cautious approach,” Juneja said.
The September report still recommended a gradual opening of workplaces so that the impact of increased occupancy in local trains and other public transport systems is manageable.
Opening of offices, schools, colleges can start this month
The TIFR scientists recommended allowing workplaces to open with 33 per cent attendance in September, 50 per cent in October and 100 per cent in November.
They also recommended social distancing in public transport, staggered timings in offices and use of shifts to whatever extent is possible, besides use of masks, encouraging regular hand hygiene and regular disinfection of high-touch surfaces in trains.
The September report also said schools and colleges can be opened in the first week of January 2021.
“Our simulations suggest that the resulting second wave from this opening up is minimal,” the September report said, adding demarcating containment zones, contact tracing and testing is still a desirable option to slow the spread of the infection.
The TIFR reiterated the recommendations in the October report, while updating a few parameters.
In the October report, the scientists suggested that Mumbai may “more or less” reach herd immunity by mid-January 2021.
“Our simulations further suggest that by mid-January 2021, the prevalence (fraction of the population infected) can be seen to be stabilising close to 80 per cent in slums and 55 per cent in non- slums. This stabilisation and high prevalence indicates that Mumbai city may have more or less reached ‘herd immunity’ by then,” the October report said.
“By this, we mean that the new infections and related medical indicators in the city will be substantially reduced compared to their peak values in mid-May and June 2020,” it added.
So far, the state government has opened Mumbai’s local trains only for essential services staff, and subsequently added certain categories of workers such as bank employees, Mumbai’s dabbawalas to the list of those permitted to use the suburban railway network. It is yet to take a decision on opening the entire network for the larger public.
Schools and colleges too are yet to open, while private offices are still permitted to function only with a 50 per cent capacity.
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