When he heard about a neighbour testing positive for Covid-19 in the first week of August, Murugan*, a 33-year-old car driver living in Vardhammal Garden in Kilpauk panicked.
He and his three family members were having fever, but they chose not to go to the Covid testing centre the corporation had set up in the neighbourhood.
By August 9, when the street had reported 18 fresh cases and death, Murugan rushed his family to the Kilpauk Medical College Hospital (KMCH) for the test. All four tested positive for the novel coronavirus.
By now, the corporation workers were trying to wrap their heads around what was clearly a Covid cluster. Their biggest challenge was identifying the source of every fresh infection in the neighbourhood.
“It wasn’t an easy task,” said Dr S Venkataramanan, Thiru Vi Ka Nagar zonal health officer and the main investigator of the cluster.
A cluster is defined as a street, apartment or locality with more than 10 Covid cases.
There was another, with 23 cases in an apartment complex on Model School Road in Sholinganallur that the civic health authorities were grappling with.
It all began on August 5, when a 47-year-old woman at Varadhammal Garden Second Street told a fever surveillance worker that she was running temperature. “She refused to take the test,” said Dr Venkataramanan.
On August 7, he received a call from KMCH that the woman was undergoing treatment for Covid. In the next two days, health workers collected samples from every resident of the neighbourhood.
Twenty of them tested positive.
“They all evaded questions on who they were in contact with, we had to talk and talk,” said the health officer,” said Dr Venkataramanan.
It virtually took life to get the first bit of useful information.
“Soon after the woman (a diabetic) at KMCH died on August 9, a woman on a neighbouring street reported that her 11-year-old boy was unwell and that they were related to the woman who died.
“And then she gave the crucial piece of information: Most of the neighbours had gathered for a temple function on August 1. That helped us draw connections,” said the doctor.
The deceased woman had worked as a helper for a temple trustee, whose six family members later tested positive for the virus. Health workers found that another auto driver, Mahesh* , whose family tested positive for the virus, had driven the women to Broadway to buy flowers for the temple festival.
The investigators then found that car driver Murugan’s father, also an autorickshaw driver, and his three family members were also infected.
It turned out that Murugan had also worked at the house of a doctor who was hospitalised with Covid in the third week of July. But since Murugan tested positive only on August 9, investigators ruled out the doctor connection and refocused on the temple as the hotspot.
“We issued a notice to the temple trustee for not informing the civic body about the event in which 150 people participated. We tested 385 people including their contacts and 20 turned positive. The cluster has been isolated and no new cases have been reported since August 9,” said Dr Venkataramanan.
It wasn’t easy for senior officers either.
Health secretary J Radhakrishnan, who visited the neighbourhood, was greeted with a “curse” by a self-proclaimed godwoman who was upset with the temple being closed.
Amidst faith and superstition, a fact stands out: Of the 24 people infected in the neighbourhood, 22 were not vaccinated, and all the 22 had to be hospitalised. (Names changed)
Sholinganallur: Where a shopper brought the virus to a park
The corporation’s cluster busters had it equally tough at Sholinganallur, where 23 people – 15 of whom had received at least one dose of the vaccine – in an upmarket residential complex tested positive.
Residents, like the ones in Kilpauk, were initially hesitant to talk about the places they visited, the people they met in the previous weeks.
The investigators, however, were able to identify the index case (the first person to get infected in a cluster) early.
The woman resident of the apartment complex who had visited VHS Hospital on July 28 for kidney treatment tested positive on August 1.
The same day, the corporation set up a camp on the apartment premises.
The next day, another woman, who had gone shopping on Mint Street, tested positive.
Tests through the next three days found 21 more people including six children who did not go out of the compound to be infected.
Curiously, not all parents or relatives who lived with some of these children tested positive, indicating that the children were getting it from someone within the premises but not a family member.
It was time to get the residents to talk. Corporation zonal officers opened new channels of communication with the residents and field staff remained persistent in their interactions.
“We got the first vital input from a resident who said the two women who tested positive later, would sit on the park bench where the children played,” said zonal health officer K Usha.
“We found 15 others who tested positive were frequent walkers in the park and they all used the same lift, often not wearing masks.”
Some 25km away, at Ripon Buildings, senior officers including corporation commissioner Gagandeep Singh Bedi were piecing together the puzzle.
“We reviewed every case every day and traced every contact to find the sources of infections to make intervention,” said Bedi.
From the cluster, 17 were kept in home isolation, five moved to Covid centres and one to a hospital.
Dr Manish Narnaware, deputy commissioner, health said people in both clusters were mapped for comorbidities and the teams maintained extensive datasheets.
“Early identification and tracing contacts are the key,” he said.
Dr P Ganeshkumar, epidemiologist, National Institute of Epidemiology, highlighted the importance of identifying all contacts of a cluster and testing them.
“Cluster investigation reduces new variants of the virus,” he said.