India, Aug. 24 -- As swine flu cases rise in the national capital, the administration has advised people to wear masks in crowded places, wash hands frequently, avoid contact with anyone who appears to be infected, and consult a doctor if they develop flu-like symptoms. Such advice may be useful, but the larger question remains unanswered. In cities defined by density - where people live, study, work, commute, shop, and socialise in closely packed spaces - can close contact among residents realistically be limited to control the spread of infections? One could argue that physical distancing was an important part of the Covid-19 containment strategy, but that was a once-in-a-lifetime pandemic needing extraordinary measures, including lockd...