Bengaluru, June 17, 2020: When a 65-year-old man died of a heart attack in a Bengaluru hospital in April and later tested positive for novel coronavirus —one of the first Covid-19 deaths in the city—health authorities and police traced his 104 contacts, 28 primary and 76 secondary, and quarantined them for testing.
One of the key factors in Karnataka’s largely successful efforts at controlling Covid-19 in the state so far has been this aggressive contact-tracing, quarantining and testing, carried out by health authorities with the help of the civic administration, police and technology.
As of Saturday, Karnataka had 6,824 cases, 3,092 of them active. It has seen 81 Covid-19 deaths, 29 of them in Bengaluru, a remarkably low number compared to other big states and metros.
Researchers from the Indian Council of Medical Research who conducted a study of contacts tested of Covid-19 patients in different states between January 22 and April 30 found Karnataka at the top, with 93 on average tested compared to the national figure of 20. The worst-affected states like Maharashtra and Delhi have tested only eight and nine contacts respectively on average.
The ICMR exercise was part of a larger study on ‘Laboratory surveillance for SARS-CoV-2 in India’. It has been released as a pre-print.
Incidentally, the study was carried out during a period when the Covid-19 numbers were still low in the country. With the numbers surging, contact-tracing has been on the decline. On Thursday, with Delhi cases at 32,810, state Health Minister Satyendar Jain said tracing was now being done only for immediate contacts of patients. “Earlier, in one case, contact-tracing would be done for up to 600 people, and today, if we multiply 1,500 cases with 600, it gives us 9,00,000 people for contact-tracing,” he said.
Apart from Karnataka, states falling within the high-performance 75th percentile for contact-testing are Kerala and Tamil Nadu, with 40 and 44 contacts tested per Covid-positive person.
“Corrected for missing data from our sensitivity analysis, the average number of contacts tested per positive case was 20.4 at all-India level and ranged from 6.6 in Chandigarh to 1387 in Tripura,” says the study.
Even in terms of testing of only primary contacts, Karnataka ranks high, with 47 per case, compared to a national average of six. Delhi tested 2.1 primary contacts, Maharashtra 2.3 while Kerala and Tamil Nadu tested 11 and 14 primary contacts per positive case.
On primary contacts, the study says, “At the national level, the average number of contacts tested per laboratory-confirmed case was six. At the state level, the average number of contacts tested per positive case ranged from 1.3 in Jharkhand to 328 in Tripura.”
It adds, “Among the top 10 states/UTs, based on the reported number of Covid-19 cases, the average number of (primary) contacts tested per positive case was more than the national average in Tamil Nadu (14.4), Uttar Pradesh (9.8), Telangana (8.1), Andhra Pradesh (7.7), Madhya Pradesh (7.6) and Rajasthan (6.3).”
The study also found the rate of Covid-19 infection among contacts to be the highest in states like Maharashtra and Delhi, where contact testing was found to be low — with 11% of all contacts testing positive in Maharashtra (13% among primary contacts) and 9% in Delhi (15% of primary contacts). On the other hand, in Karnataka, 1% of contacts tested positive (also 1% of primary contacts) and in Kerala 2% (3% among primary contacts). Tamil Nadu was also at the lower end of the spectrum.
The national average for Covid-19 positive tests among all contacts of a case was 4%, with the figure at 6% for primary contacts.
“Every patient and contact is equally critical to be traced and tracked to control the spread of the infection. One never knows who will end up spreading Covid-19 to a large numbers of persons,” Munish Moudgil, the IAS officer in-charge of the Karnataka Covid-19 war room, said.
Moudgil stressed on the importance of identifying the contacts of every patient within 24 hours and quarantining them for 14 days.
While contact-tracing was carried out physically by health workers in the early days of the spread of the disease in Karnataka, the exercise is now carried out with the help of technology and a large battalion of government field staff.
Despite nearly 70% of the 3,092 active Covid-19 cases in Karnataka being new arrivals from other states, contact-tracing has managed to keep pace. As of Saturday, 35,552 primary and secondary contacts of Covid-19 cases were in quarantine.
Explaining the app they had developed for the purpose, Moudgil said, “The contact details picked from a patient in a hospital are entered into this Contact Tracing App. The information immediately flows to field teams. The local team goes and quarantines the contact.”