As Covid-19 spreads, the silver lining
infect, but remain in the air longer, creating tangible infection risks in closed, crowded and poorly-ventilated spaces. Wearing a mask reduces the droplets we send out and those that we breathe in. Comfortable surgical masks, or almost any mask, do a good job of the former, while N95 respirators are required to effectively do the latter. If everyone is wearing a mask, N95 is not required and people can stay comfortable and protected. This is the simplest strategy to reduce not only the number of infections, but probably also the severity of infection, since it seems that a higher amount of virus exposure may lead to higher chances of severe disease.
The other necessary intervention is to restrict indoor crowding and increase fresh air ventilation. As the summer comes to an end in about a month, it will become possible to bring in fresh air without compromising the temperature control of air-conditioned buildings. However, optimal design of indoor spaces is still a problem that requires thought on the part of architects and engineers, especially for restaurants where masks are not possible. Rapid air exchange with filtration or decontamination is a viable option where fresh air cannot be brought in.
The other critical need is to destigmatise Covid-19. None of us know where it is coming from, but there is no reason for panic beyond rational precautions. Most people can safely self-isolate and recover at home, preferably without any consternation on the part of neighbours. Reverse isolation, in which highrisk people are temporarily isolated, is another option. The large number of infections has a silver lining: When managed well, there will be a large fraction of recovered people with some immunity. Herd immunity is still some distance away as a nation, but local immunity may be sufficient to prevent large outbreaks in such areas. In data collected by others and us, about 20-30% of Delhi and Mumbai residents seem to be in the recovered category based on antibody presence, although these are not neutralising antibodies with definite anti-virus action.
A very positive sign is that there have been no proven re-infections in over six months of global experience, despite poor antibody response and lack of neutralising antibodies in many people. Better immunity tests will allow immunity passports for those who can safely serve at the frontline of critical highrisk services. The size of our problem may yet become the size of our opportunity. It is time, despite the doom and gloom, to start thinking of the new normal.