Chennai, which has 14,997 active COVID-19 cases, has begun serosurvey, wherein healthcare professionals will directly collect blood samples from residents’ doorstep.

Health worker checks temperature for a family in chennai as father son daughter and mother stand outside their house
Coronavirus Coronavirus Sunday, July 19, 2020 - 11:41

In an interim relief, Greater Chennai Corporation Commissioner G Prakash on Saturday said that the doubling time of COVID-19 in Chennai is now at 47-days, and compared it with the national average of doubling time that stood at 21 days. Doubling time refers to the time taken for the number of infections to double from a given day. According to reports, on July 6, the doubling rate was at 25.42 days.

The Commissioner pointed out that this doubling time was well ahead of Indian Council of Medical Research (ICMR) and World Health Organisation’s (WHO) standard of 14-days, which indicated a positive trend in the city. Chennai is among the biggest COVID-19 hotspots in the country.

He also added that doubling time of cases in Royapuram, the biggest hotspot in Chennai, had also increased to 90 days. The Commissioner said that testing has been ramped up in the city and about 13,000 samples were tested in the city just on Saturday.

Commissioner Prakash further said that works are underway to bring down the positivity rate in the city from 10-12% to 8-10%. Positivity rate indicates the number of persons testing positive against the total number of persons being tested.

Serosurvey in Chennai

Chennai, which has 14,997 active COVID-19 cases, has begun serosurvey as part of which healthcare professionals will directly collect blood samples from residents’ doorstep. According to the Commissioner, this will be completed in 10 days, during which all parts of the city will be covered. Random blood samples from 12,000 persons will be collected and studied for this purpose.

According to a report in The Hindu, a serosurvey conducted by ICMR many weeks ago showed that 2% of Chennai’s residents had been exposed to novel coronavirus infection. GCC’s serosurvey conducted on Corporation staff on Thursday showed that 15 to 20% of them were exposed to SARS-CoV-2.

Pool testing to begin

Minister of Health and Family Welfare C Vijayabaskar on Saturday announced that pooled testing for COVID-19 will begin soon, mainly to reduce the turnaround time of results.

In pooled testing, instead of testing each person individually, samples from five different individuals will be tested as a single unit by the RT-PCR method. If the test returns negative, all five in the pool are considered to have tested negative. Should the result return positive,  then each member is tested individually.

Twenty-one districts with 2-5% positivity rate have been identified for this purpose. Villupuram, Tirunelveli, Trichy, Coimbatore, Salem, Erode, and Pudukkottai are among the 21 districts identified for pooled testing.

Director of Public Health and Preventive Medicine, in its order dated July 17, has informed all nodal officers in both government and private labs to implement pooled sample testing. The state presently has 111 COVID-19 testing centres, which include 56 government and 55 private centres.

Health Secretary J Radhakrishnan pointed out that with the number of samples being tested in districts increasing, pooled testing is being looked at as a solution. “The turnaround time for results is up to six days in some districts. So we are pushing for pooled testing,” he was quoted saying.

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