What has been a little unexpected, however, is the fact that reproductive number for Maharashtra has continued to decline even more than two weeks after the lockdown easing. Read | Health infrastructure only 1 per cent of Smart City projects In many other states, there have been disruptions, caused either by specific triggers like a super spreader event, or reporting of inconsistent or low-quality data,” he said. The growth did slow down a bit because of the lockdown but, overall, the curve is exactly what one would expect it to be. “In fact, Maharashtra is probably the only state which has followed an almost textbook example of an epidemic curve. Unlike many other states, the growth of infections in Maharashtra has been unabated, and it never had any “passive” phase. Read | Last 10 days, positivity curve begins to steepen I am not very surprised to see that it is Mumbai where we are seeing this kind of growth and not any other city or region,” Menon said. But, even amongst these cities, Mumbai probably presents the most complex challenge. A similar situation is being played out in other cities like Ahmedabad, Delhi, or Chennai as well. “In a way, Mumbai is representative case of how difficult it is to contain an infectious disease in dense urban settings. Gautam Menon, a professor of computational biology and theoretical physics, also at the Institute of Mathematical Sciences, said containment would probably have been easier if, instead of being in Mumbai, a similar number of cases were located at some other place even if the geographical spread was a little more than the size of Mumbai. But the idea of putting entire cities under quarantine has huge practical difficulties, especially if the cities are as important for financial and industrial well-being of the country as Mumbai and Pune. Theoretically, if we are able to ensure that no infected person goes out of this area, eventually the disease will tire itself out in this area, without contributing much to the spread elsewhere,” said Sitabhra Sinha of the Institute of Mathematical Sciences in Chennai who has been tracking the spread of the disease. It is this one contiguous region that is the biggest problem area. An overwhelming number of infections are just in the two cities of Mumbai and Pune and their suburbs. Even in Maharashtra, the entire state is not equally affected. Theoretically, this entire area can be isolated, and movement to and from this area can be restricted. “From a containment perspective, it is good if a large number of infections are concentrated within a small geographical area. Read | Maharashtra minister Ashok Chavan tests positive In other words, if the outbreak in Maharashtra is somehow contained, or its growth slowed down, a sizeable part of the problem in the country would be taken care of.

Map of maharashtra state