Ambulance drivers at Pathanamthitta General Hospital get ready to take people to isolation ward on Wednesday

THIRUVANANTHAPURAM : Hours after five Covid-19 cases were confirmed in Pathanamthitta, district administration and health department knew that they were in for a massive tracing exercise because one-to-one interviews with the affected persons gave a picture of a large ring of contacts.

Tracing and establishing communication with primary and secondary contacts within the minimal possible time was the challenge. The flowchart depicting date, time and place of movement of affected persons within three clusters was the result of a midnight discussion attended by the state health secretary, NHM state mission director and Pathanamthitta collector PB Nooh.

Officials were looking for a solution for fast-tracking the isolation process and spatio-temporal mapping (STM), which employs data on time and space of movement from a single point to multiple destinations, emerged the best ploy.

“We had to beat the virus and manual surveillance was the first choice. Instead of going after primary and secondary contacts, we wanted info on them to reach us. We thought of STM since it enabled plotting on map and date, time, place stamping. It also ensured greater public participation. Soon after we released the flowchart, we started receiving calls from places we had denoted in the flowchart and each call gave us useful information,” said NHM state mission director Rathan Kelkar.

Over the past three days, 900 primary and secondary contacts were traced and put under isolation. For that to happen, storylines were made, route maps were drawn. Before the mapping process, the team from community medicine started with direct interviews that yielded incomplete data because the patients were not forthcoming. The team then collected call details of the patients between February 29 till their time of hospital admission. The search produced 250-300 numbers.

“We contacted each person on phone and traced how many of them were in personal contact with the patients and where. It also gave us information about 15 persons who were not actually on our list,” said Nooh. Seventeen field teams, each comprising six members, then collected CCTV footage and data from supermarkets, shops and post offices.

By evening, the team sat together with different set of data and missing links were marked for further verification. A storyline would be made for each cluster of patients and data, made available using STM, helped finetune the details. For instance, the preliminary information about the hotel, which was a point of contact, was that it was somewhere between two distant locations. The team did more digging to arrive at a time, exact name and location of the hotel. It was added as the last entry.

As a final verification process, tower location of affected persons between February 29 and March 9 were collected. There was a confusion over the hotel they had visited. While some people told the team where the persons were spotted, they couldn’t corroborate it since hotel records and CCTV footage did not yield anything. In that case, tower location was used to know whether the parties were anywhere near the location of hotel.

A three-member team led by district informatics officer Gigi George put together manually derived information, route maps and CCTV data to prepare STM. “We received over 100 calls and feedback from the public helped to ensure crucial corrections and updation on STM,” said NHM district programme manager Dr Abey Sushan. The name of a bus was corrected, timing of patient’s arrival in a place was made more accurate based on public response.

