Slums in Mumbai breathed easy in the second Covid-19 wave

Mumbai In the second wave – marked by more infectious and transmissible new strains of Sars-Cov-2 – the cumulative Covid-19 cases in Mumbai surged by four times as compared to last year

Mumbai In the second wave – marked by more infectious and transmissible new strains of Sars-Cov-2 – the cumulative Covid-19 cases in Mumbai surged by four times as compared to last year. However, the city’s slum pockets, where the possibility of prevalence and spread of the novel coronavirus infection was considered to be higher, showed more resilience, while the high-rise buildings turned into epicentres of transmission.

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Public health experts, non-governmental organisations (NGOs) and medical practitioners have cited several reasons for fewer Covid-19 cases in slums. These include development of natural antibodies among slum dwellers that acted a protective shield, quicker response by stakeholders, the ongoing vaccination drive and better awareness. The civic body is now prepping up for studies to find answers for the change in the epidemiological characteristic of the pandemic.

In March 2020, when Covid-19 struck Mumbai, the virus spread from residential buildings to slums, which emerged as the biggest cause of concern owing to their dense population. Asia’s biggest slum Dharavi was declared a ‘red zone’ area. Many slum dwellers migrated to their villages and no one was allowed to enter or exit containment zones, bringing the life of hundreds of residents to a standstill.

As a result, public health experts feared a repeat of last year’s scenario at the start of the second wave in mid-February, especially due to mutation of the virus. However, data from the Brihanmumbai Municipal Corporation (BMC) shows that 90% infections in the second wave were recorded in high-rise buildings. By the beginning of March this year, the civic body realised that the main challenge was to contain the spread of Covid-19 in in high-rise buildings and not slums. As on April 30, when Mumbai was at the peak of the second wave, 9,899 floors were sealed and 979 buildings were declared active containment zones, while the city’s slums had only 111 containment zones.

Slums hit in first wave

More than 50% (6,534,460) of Mumbai’s total population of 12,442,373 (as per 2011 census) resides in slum areas, making the inhabitants vulnerable to contracting the infection owing to their poor and unhygienic living conditions. Public health experts said slum pockets, from where a significant proportion are employed as domestic help, drivers, guards, gardeners in high-rise buildings, are like ticking bombs that can cause the virus to spread like a wildfire among the general population.

Dharavi inhabitants, for instance, live in some of the most cramped spaces in the country. In an area measuring 2.1 square kilometres (sq km), the slum has over 57,000 shanties, huts and small flats, almost all being illegal. Its estimated population density – 66,000 people per sq km – is more than double of Mumbai (32,303 people per sq km), the fifth most-densely populated city in the world, according to a United Nations Population Prospects study released in July 2019.

Till February 7, the area had reported 3,947 Covid-19 cases and 312 deaths. However, in the second wave, a total 2,917 cases and 47 deaths have been reported since February 1 till June 18. Of the total 6,864 infections, around 42% were reported during the second wave. At present, there are only five active Covid-19 cases. On June 15, Dharavi reported zero Covid-19 cases – a first since February 2.

Civic ward officials said the infection rate this year was less than that in 2020 despite conducting similar number of daily Covid-19 tests during both the waves.

“In May 2020, when the pandemic curve was at its peak, we tested 200-250 people every day. We undertook the same number of tests in the second wave too. By mid-March, we started observing that the infection rate was rising in high-rises than the slums. We then gradually started focusing on residential buildings,” said Kiran Dighavkar, ward officer, G-South ward that covers Dharavi, Mahim and Dadar.

The trend is similar in other civic wards where the slum population is in a majority. For instance, L ward that covers Kurla constitutes over 80% slums. Manish Walunj, assistant municipal commissioner of the ward, said around 3,500 tests were conducted every day between March and May this year and last year, but the infection rate was lower than the first wave.

“In mid-May last year, slum pockets in our ward had the highest number of containment zones (131) covering 10,699 households. But by April-end this year, we had only 15 active containment zones in slums. As on June 15, our ward has only 458 active patients, and over 90% are from non-slums,” said Walunj.

The M-East ward, which includes slum clusters of Govandi and Mankhurd, has also witnessed a significant drop in cases compared to last year.

“In May last year, the growth rate was 8.4%. In April this year, it was 4%. At the start of the second wave, we also increased our contact tracing to 17 individuals per infected patient,” said Dhanaji Herlekar, assistant municipal commissioner, M-East ward.

Civic-run hospitals have also witnessed a significant fall in hospitalisation cases from slums in the second wave. Dr Mohan Joshi, dean of Lokmanya Tilak General Hospital (Sion hospital), said, “There has been a 40-50% drop in hospitalisation of slum dwellers in the second wave. There was a spike in admissions in April but the death rate was minimal, below 1%.”

Fewer Covid-19 cases in the city’s densely populated slum pockets have left public health officials curious about the possible reasons for low infection rates.

Dr Varsha Puri, deputy executive health officer of zone-5 that covers areas including L, M-East and M-West wards, said, “To get answers as to why slums recorded fewer cases in the second wave, we have decided to conduct studies in these civic wards to understand the epidemiological characteristics of the virus. We are awaiting guidelines from BMC to initiate the study in slums.”

Seropositivity higher in non-slum areas

The first and second serological surveys in Mumbai, to ascertain the prevalence of antibodies, were conducted in July and August 2020. The third was conducted in March across all the 24 civic wards, which showed the presence of antibodies in 36.3% of the total 10,197 samples. Results of the third survey showed an increase in seropositivity rate in non-slums as compared to slums. The sero survey in slum areas showed seropositivity at 41.6% as against 57% and 45% in last July and August, respectively. In non-slum areas, the seropositivity was found in 28.5% samples (which increased from last July and August’s 16% and 18%), making the population more vulnerable to Covid-19 during the second wave.

Dr Lancelot Pinto, pulmonologist, Hinduja Hospital, said, “The fact that most of the cases in the second wave were in high-rises possibly suggests two things— the rates of re-infection were low or, most of the infections were likely in individuals who hadn’t encountered the virus in the first wave, and were therefore vulnerable.”

Dr Ravikant Singh, founder, Doctor For You, said natural antibodies produced in the first wave is still circulating among slum dwellers, making their immunity stronger to fight the virus.

“In the second wave, the mutation of the virus made the infection more transmissible. This could have had severe repercussions in the densely-populated slums. But I assume that many who had already been infected once, have natural antibodies against the virus, and hence, have reduced risks of getting infected during the second wave. We however need to understand that it is just a temporary shield,” said Singh.

Mass immunisation drives are therefore the need of the hour before the natural antibodies produced in the body become weak, said civic officials.

“Antibodies remain in the body for four-six months. There is strong likelihood that once the slum population loses them, we could again see the virus spread through slums if there is another wave, unless we can catch up on vaccinations,” said Walunj.

Dr Pinto suggested that prioritising vaccination for individuals in areas with low seroprevalence, especially among high-risk individuals, would possibly be a high-yield strategy.

“We need to also conduct regular seroprevalence studies coupled with whole genome sequencing to identify vulnerable populations and variants of interest before they spread rapidly,” he said.

Amita Bhide, dean, school of habitat studies, Tata Institute of Social Science (TISS), who has conducted several studies in M-East ward during the second wave, said the vaccination drive is still lagging in slums.

“The priority has been middle and high-class [groups] as the infection rate among them was high. As vaccination in slums is facing a setback, there is a need to bring the drive to people’s doors. Individuals in slums are still sceptical about the need for vaccination. Hence, the civic body also needs to focus on awareness,” said Bhide.

The Covid-19 containment proactive strategies not only helped BMC in controlling cases in slums, but their ‘Dharavi model’ also bagged them national fame and appreciation.

Through door-to-door surveys at slums, BMC created a health map that helped diagnose Covid-19 patients faster and maintain a record of high-risk patients who were immediately isolated in Covid Care Centres (CCC).

“We followed three strategies in slums— test, isolate and treat. Other than RT-PCR (reverse transcription polymerase chain reaction), we have been conducting rapid antigen tests on the floating crowds in slums. In Dharavi, we have also started mobile van testing facilities,” said Suresh Kakani, additional municipal commissioner.

Growing awareness among slum dwellers also helped curb transmission from residential buildings.

“The first wave has taught slum dwellers lessons that helped them survive the second wave. They were extra careful and cautious even while serving in residential buildings. The question that now remains is how safe will slums be in the third wave,” said Bhide.

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Domestic workers’ concern

Dharavi resident Sunita Pradhan, 36, who lost her job as a domestic help last year, was terrified when the second wave hit the city. Like Pradhan, many domestic workers were anxious to work in high-rise buildings. In many cases, domestic helps were not informed by their employers if any of their family members contracted Covid-19.

“In the first wave, we were asked to get Covid-19 test reports. In the second wave, they [employers] started hiding about Covid-19 among their family members from us,” said Pradhan.

Ashish More, 41, who works as a security guard at a Carter Road apartment, said that during the second wave, those working as drivers, guards, cooks, gardeners in the high-rise building had to be extra cautious.

“We had to wear double masks and regularly use hand sanitisers. They are our employers. So unlike them, we can’t ask for vaccination certificates or Covid-19 reports to work for them. But at least now, the employers treat us better and don’t shoo us away,” said More who lives in a 150 sq feet chawl in a slum at Bandra (East) with five family members.