Navigating the unknown
From the very beginning, India's fight against COVID-19 has been a monumental task, more so than other countries due to a variety of factors. The largest of these factors was simply population and its density in certain areas where controlling the spread was seen as vital in efforts to prevent truly nightmarish scenarios. One of these potential nightmarish scenarios revolved around the densely populated slums of Mumbai. When the first few cases were being reported in and around Dharavi, one of the largest slums in Asia, the panic was very real. Authorities scrambled to test and isolate in an area where social distancing was near impossible and certain utilities like bathrooms were shared by multiple families in an area. As the nation at large saw a massive spike in COVID-19 numbers, Mumbai's slums too saw a spike but the situation did not deteriorate to its worst-case scenario. Eventually, an aggressive campaign of isolation and testing succeeded in managing the spread of the pandemic in the slums. The efforts of the various involved authorities were even lauded by the WHO for the sheer odds they faced. The story it seemed had reached a safe enough conclusion with only a handful of daily cases being reported from the slums in recent times. But a new study has presented an interesting possibility in this scenario which can be chilling or hopeful depending on how one chooses to interpret the results.
Recently, Mumbai's municipal authority carried out a survey in three civic areas in city with the help of Niti Aayog and the Tata Institute of Fundamental Research. The areas chosen were Chembur, Matunga and Dahisar. A sero-surveillance study was carried out by the authorities and close to 7,000 samples were used. The objective was to determine the presence of COVID-19 antibodies. The presence of such antibodies in a person would indicate that person had contracted the infection and had since recovered. The study found that 57 per cent of slum dwellers in the three specified areas had developed the antibodies. In comparison, only 16 per cent of the non-slum residents in the same area had antibodies. The survey also confirmed that a majority of these cases were asymptomatic. It also confirmed beyond most reasonable doubt as to how population density and lack of proper social distancing play a role in contributing to the easy spreading of the contagion. Conversely, it also shows how the use of the prescribed methods of social distancing and hygiene have visible effects. Another fact that was noted was that there was a higher prevalence of the antibodies in women, both in the slums and outside. Most importantly, the study showed that the virus has likely affected Mumbai's slums more significantly than previously thought. Experts associated with the study have asserted that the samples tested were "statistically robust" and representative. While they have noted that the study cannot be deemed conclusive with just three wards being tested, they are reasonably certain that the pattern observed in the study will generally hold in other areas in Mumbai as well.
Doom and gloom over the potential discovery aside, there are certain other things worth noting. It was noted that a large section of people survived being infected with little or no symptoms in these areas, which would indicate a low fatality rate. At this stage, as the caseload in Mumbai has somewhat slowed down, it begs the question as to how close the city could be to the much-coveted state of herd immunity. Herd immunity is only possible when a certain population has had enough infections among it for a majority of the people to have the antibodies. In these cases, even if there are those who do not have the antibodies, the virus quite simply does not have enough room to amply spread and naturally recedes. This study, as noted by a Brihanmumbai Municipal Corporation release, will prove valuable in learning about possible herd immunity.
The scientists involved have been more cautious in this assertion. They noted that there is no information on exactly how long the antibodies work to keep the person safe from another bout of COVID-19 infection. It is known for instance that the level of antibodies can decrease in certain patients after 90 days. Sweden's experience with herd immunity shows that banking on such hopes can be counterproductive. Even the architect of Sweden's low-intensity response has stated that their approach may not be the best idea, even if it seems to be doing good for the economy. As with all things, more research and time is needed. Those in-charge of the Mumbai study have indicated that several more series of such surveys will be carried out in the coming months.