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Pooling Five COVID-19 Samples May Not Lead To Much Loss Of Sensitivity Even For Low Viral Loads: ICMR Scientist

The Indian Council of Medical Research (ICMR) conducted a study to understand comparative analysis of pooled testing for five and 10 sample pools by RT-PCR at ten different laboratories conducting COVID-19 testing across the country

Pooling Five COVID-19 Samples May Not Lead To Much Loss Of Sensitivity Even For Low Viral Loads: ICMR Scientist

New Delhi: A study done by the Indian Council of Medical Research (ICMR) has revealed that pooling five samples to detect coronavirus by RT-PCR may be an acceptable strategy without much loss of sensitivity even for low viral loads, while with 10-sample pools there could be considerably higher numbers of false negatives. The study was done to understand comparative analysis of pooled testing for five- and 10-sample pools by RT-PCR at ten different laboratories conducting COVID-19 testing across the country.

The findings of the study have now been published in the latest edition of the Indian Journal of Medical Research (IJMR).

Also Read: Coronavirus Outbreak Explained: What Is Pool Testing And Can It Expedite COVID-19 Detection In The Country?

Dr Nivedita Gupta, a scientist at ICMR and author of the study, said that the laboratories are facing huge sample loads for COVID-19 diagnosis by RT-PCR.

The high sensitivity of optimized real-time RT-PCR assays makes pooled testing a potentially efficient strategy for resource utilization when positivity rates for particular regions or groups of individuals are low. We conducted a comparative analysis of pooled testing for 5- and 10-sample pools by real-time RT-PCR across 10 COVID-19 testing laboratories in India, she said.

At least ten virus research and diagnostic laboratories (VRDLs) testing COVID-19 by RT-PCR participated in this evaluation.

At each laboratory, 100 nasopharyngeal swab samples including 10 positive samples were used to create 5- and 10-sample pools with one positive sample in each pool. RNA extraction and real-time RT-PCR for SARS-CoV-2-specific E gene targets were performed for individual positive samples as well as pooled samples, Dr Gupta said.

The scientist said that concordance between individual sample testing and testing in the 5- or 10-sample pools was calculated and the variation across sites and by sample cycle threshold (Ct ) values was analyzed.

Results from this multi-site assessment suggest that pooling five samples for SARS-CoV-2 detection by RT-PCR may be an acceptable strategy without much loss of sensitivity even for low viral loads, while with 10-sample pools, there may be considerably higher numbers of false negatives. However, testing laboratories should perform validations with the specific RNA extraction and RT-PCR kits in use at their centres before initiating pooled testing, she said.

Also Read: ‘On-Demand’ COVID-19 Testing For All Individuals, No Delays In Emergency Procedure Due To Lack Of Testing: Health Ministry

(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.) 

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World

22,70,55,138Cases
18,97,86,461Active
3,25,98,424Recovered
46,70,253Deaths
Coronavirus has spread to 195 countries. The total confirmed cases worldwide are 22,70,55,138 and 46,70,253 have died; 18,97,86,461 are active cases and 3,25,98,424 have recovered as on September 17, 2021 at 5:36 am.

India

3,33,81,728 34,403Cases
3,39,0563,867Active
3,25,98,424 37,950Recovered
4,44,248 320Deaths
In India, there are 3,33,81,728 confirmed cases including 4,44,248 deaths. The number of active cases is 3,39,056 and 3,25,98,424 have recovered as on September 17, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths
Maharashtra

65,11,525 3,595

52,893 310

63,20,310 3,240

1,38,322 45

Kerala

44,46,228 22,182

1,86,754 4,559

42,36,309 26,563

23,165 178

Karnataka

29,65,191 1,108

16,202 282

29,11,434 808

37,555 18

Tamil Nadu

26,40,361 1,693

16,756 120

25,88,334 1,548

35,271 25

Andhra Pradesh

20,34,786 1,367

14,708 105

20,06,034 1,248

14,044 14

Uttar Pradesh

17,09,628 23

193 11

16,86,549 11

22,886 1

West Bengal

15,59,567 707

8,025 25

15,32,922 725

18,620 7

Delhi

14,38,373 28

409 5

14,12,880 22

25,084 1

Odisha

10,18,298 580

5,335 105

10,04,845 681

8,118 4

Chhattisgarh

10,04,988 31

352 2

9,91,077 29

13,559

Rajasthan

9,54,230 4

103 1

9,45,173 5

8,954

Gujarat

8,25,677 22

149 0

8,15,446 22

10,082

Madhya Pradesh

7,92,374 7

119 5

7,81,738 12

10,517

Haryana

7,70,697 9

327 8

7,60,562 17

9,808

Bihar

7,25,864 12

72 6

7,16,134 6

9,658

Telangana

6,62,785 259

5,282 43

6,53,603 301

3,900 1

Punjab

6,01,180 30

314 11

5,84,399 38

16,467 3

Assam

5,97,074 468

5,381 15

5,85,914 479

5,779 4

Jharkhand

3,48,102 6

102 8

3,42,867 14

5,133

Uttarakhand

3,43,330 20

284 12

3,35,657 32

7,389

Jammu And Kashmir

3,27,466 170

1,421 72

3,21,630 98

4,415

Himachal Pradesh

2,16,430 127

1,568 82

2,11,215 206

3,647 3

Goa

1,75,183 95

699 1

1,71,195 96

3,289

Puducherry

1,25,170 107

963 63

1,22,380 42

1,827 2

Manipur

1,17,913 216

2,614 7

1,13,478 219

1,821 4

Tripura

83,787 31

427 26

82,553 56

807 1

Meghalaya

78,958 229

1,804 140

75,784 86

1,370 3

Mizoram

76,591 1,121

13,888 85

62,449 1,202

254 4

Chandigarh

65,168 4

31 2

64,319 2

818

Arunachal Pradesh

53,990 47

536 9

53,183 56

271

Sikkim

30,802 64

775 28

29,648 36

379

Nagaland

30,763 32

505 14

29,610 44

648 2

Ladakh

20,631 6

41 1

20,383 5

207

Dadra And Nagar Haveli

10,670

5 0

10,661

4

Lakshadweep

10,353

4 0

10,298

51

Andaman And Nicobar Islands

7,595 3

15 2

7,451 1

129

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