Experts Explain The Different COVID-19 Tests: Rapid Antigen Vs RT-PCR Test, Which Is Better?

Experts Explain The Different COVID-19 Tests: Rapid Antigen Vs RT-PCR Test, Which Is Better?

Both RT-PCR test and Rapid Antigen Test lookout for the virus in the sample and are used for the diagnosis of COVID-19
Coronavirus Outbreak, News
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Experts Explain The Different COVID-19 Tests: Rapid Antigen Vs RT-PCR Test, Which Is Better?COVID-19 testing: RT-PCR test is considered as the gold standard for testing
Highlights
  • RT-PCR test has a high specificity rate; gives less false positives
  • Only nasopharyngeal swabs are collected for Rapid Antigen Test
  • RAT has moderate sensitivity, can give false negative results for COVID-19

New Delhi: Testing for Coronavirus has been ramped up in India from 2.07 lakh tests on June 24 to over 4.08 lakh tests per day on July 28 and 6.19 lakh samples tested on August 4. Rapid Antigen Tests (RAT) has helped in a substantial increase in testing in the country and especially in the national capital Delhi. In a media briefing on August 4, ICMR Director General Dr Balram Bhargava informed that 25-30 per cent of the tests conducted are RAT. However, it’s a known fact that RAT can give a high number of false negatives. Recently, Delhi High Court pulled UP the AAP government for choosing Rapid Antigen Testing (RAT), as the primary test of COVID-19 infection over RT-PCR (Reverse transcription-polymerase chain reaction) which is considered as the gold standard for testing.

Also Read: Delhi’s Coronavirus Trends Number Show Positive Signs But Testing Strategy Raises Many Questions: Experts

NDTV spoke to experts to understand the two main kinds of tests for COVID-19 diagnosis – RT-PCR and RAT and their reliability.

According to Dr Navin Dang, founder of Dr Dang’s lab in Delhi, all the tests available in the market for testing of COVID-19 have their own pros and cons but RT-PCR remains the gold standard for testing. Explaining the process of RT-PCR test, Dr Dang said,

This is performed by taking swabs from nasal and oral tracts which are then put in viral transport medium and brought to the lab. It is processed under bio safety level 2 plus facilities; we do RNA (Ribonucleic acid) extraction to detect the presence of the virus.

RT-PCR test has a specificity rate (ability to identify those without the disease) of nearly 100 per cent whereas the sensitivity rate (ability to identify those with the disease) of about 67 per cent. This means, RT-PCR test will not give false positives but there are 30-35 per cent chances of getting false negatives. Explaining the reason behind the low sensitivity rate and why is RT-PCR test still considered the gold standard for testing, Dr Dang said,

There are three main reasons, one, the technology itself which we cannot consider as a limitation. Secondly, if the samples are not taken properly then the result can be a false negative. This is the reason we take both nasal and oral swabs. Ideally, samples should be collected by experts who are trained to go to the nasopharyngeal or oropharyngeal cavity. Thirdly, people are now seeing it as a preventive test which means they are getting the test done even in the absence of symptoms. The average incubation period of SARS-CoV-2 is 5.6 days so an individual will test positive only after six days of contracting the virus. Undergoing a COVID-19 test at the initial stage when the viral load is very low can give negative results. Also, there is no other test that has got better sensitivity.

Also Read: Coronavirus Explainer: 20 COVID-19 Related Terms And What These Mean

At the initial stage of the Coronavirus pandemic, RT-PCR test was priced at Rs. 4,500 but now the cost has been brought down to Rs. 2,500. It is still expensive and takes a day to give results.

Talking about the time consuming process, Dr Harsh Mahajan, Founder of Mahajan Imaging and Chairman of CARINGdx, said,

In RT-PCR you can put 96 samples at a time so one has to wait for the samples to reach the laboratory and then process them. Less than 96 samples can be processed but it will increase the cost of testing.

As far as Rapid Antigen Test (RAT) is concerned, it is gaining grounds and has led to a spike in the number of tests being conducted, as it is quick and cheap. Only nasopharyngeal swabs are collected by trained healthcare workers. RAT detects the presence of viral proteins (antigens – attributes of the virus) in a sample from the respiratory tract of a person. However, it is capable of giving more false negatives. Explaining the same, Dr Mahajan said,

RAT has moderate sensitivity (around 50 per cent) and high specificity which means if you test 100 COVID-19 patients, it will give positive results for only 50 of them.

Also Read: Coronavirus Outbreak Explained: What Is Antibody Test And What Role Does It Play In The Fight Against COVID-19?

According to the ICMR protocol, if RAT gives negative result and an individual has symptoms of ILI (influenza like illness), then he/she should undergo RT-PCR test.

Also, RAT is a point of care test which means it can be performed only in hospital settings rather than standalone testing labs. Elaborating on this, Dr Dang said,

Sanctity of the test that is from the time sample is taken and is processed, is about 1 hour so it cannot be done at any collection centre. It is not possible to collect, label, transport and process the sample within one hour, even if it is collected within three to four kms from the lab.

If RAT does not provide standardised testing and results, why is India conducting RAT? Answering the question, Dr Dang said,

RAT has its own advantages in the way it can be done on a mass level. The numbers of tests that are being performed are in thousands now. The tests are being performed even in community centres, Gurdwara and other places. But too much of reliability on rapid antigen tests which shows a lot of false negatives is a questionable thing and I think the government may have to reconsider it. Right now, the number of people asking for a test is high and the number of RT-PCR tests labs are being able to provide is not that great.

Explaining how a government should increase testing with RAT and at the same time ensure it doesn’t miss COVID-19 positive patients, global health expert Anant Bhan suggests a balance between RAT and RT-PCR test. He added,

If antigen tests are being used it needs to be backed by RT-PCR test and only then we can say that yes there has been a decrease in coronavirus cases in that particular area. If the numbers of both the tests are not matching then it is a serious issue and it may reflect a bad picture.

Mr Bhan recommends all states to ramp up testing by not only increasing the number of rapid antigen tests, but also backing it by RT-PCR tests.

Also Read: Coronavirus Crisis: Community Transmission Taking Place In India, Here’s What Experts Have To Say

NDTV – Dettol Banega Swasth India campaign is an extension of the five-year-old Banega Swachh India initiative helmed by Campaign Ambassador Amitabh Bachchan. It aims to spread awareness about critical health issues facing the country. In wake of the current COVID-19 pandemic, the need for WASH (WaterSanitation and Hygiene) is reaffirmed as handwashing is one of the ways to prevent Coronavirus infection and other diseases. The campaign highlights the importance of nutrition and healthcare for women and children to prevent maternal and child mortality, fight malnutrition, stunting, wasting, anaemia and disease prevention through vaccines. Importance of programmes like Public Distribution System (PDS), Mid-day Meal Scheme, POSHAN Abhiyan and the role of Aganwadis and ASHA workers are also covered. Only a Swachh or clean India where toilets are used and open defecation free (ODF) status achieved as part of the Swachh Bharat Abhiyan launched by Prime Minister Narendra Modi in 2014, can eradicate diseases like diahorrea and become a Swasth or healthy India. The campaign will continue to cover issues like air pollutionwaste managementplastic banmanual scavenging and sanitation workers and menstrual hygiene

World

13,53,52,898Cases
5,55,33,988Active
7,68,91,122Recovered
29,27,788Deaths
Coronavirus has spread to 192 countries. The total confirmed cases worldwide are 13,53,52,898 and 29,27,788 have died; 5,55,33,988 are active cases and 7,68,91,122 have recovered as on April 11, 2021 at 4:16 am.

India

1,33,58,805 152879Cases
11,08,087 61456Active
1,20,81,443 90584Recovered
1,69,275 839Deaths
In India, there are 1,33,58,805 confirmed cases including 1,69,275 deaths. The number of active cases is 11,08,087 and 1,20,81,443 have recovered as on April 11, 2021 at 2:30 am.

State & District Details

State Cases Active Recovered Deaths
DistrictCases
Mumbai45,478
Thane13,660
Pune9,920
Mumbai Suburban5,363
Aurangabad1,974
Nashik1,575
Raigad1,462
Palghar1,421
Solapur1,291
Jalgaon1,039
Akola757
Nagpur692
Kolhapur646
Satara629
Ratnagiri350
Amravati291
Dhule228
Hingoli208
Jalna201
Ahmednagar190
Nanded176
Yavatmal150
Sangli145
Latur139
Osmanabad125
Sindhudurg114
Buldhana88
Parbhani78
gondia69
Beed54
Nandurbar42
Gadchiroli42
Bhandara41
Chandrapur32
Washim13
Wardha11

33,43,951 55,411

5,38,160 2,097

27,48,153 53,005

57,638 309

DistrictCases
Kannur357
Kasaragod333
Palakkad224
Malappuram119
Kollam118
Thrissur106
Thiruvananthapuram104
Pathanamthitta98
Kozhikode90
Alappuzha76
Kottayam73
Ernakulam60
Idukki40
Wayanad36

11,60,204 6,194

40,095 3,593

11,15,342 2,584

4,767 17

DistrictCases
Udupi1,176
Kalaburagi669
Yadgir538
Bengaluru Urban529
Raichur369
Mandya346
Belagavi337
Bidar219
Hassan205
Davangere204
Vijayapura201
Dakshina Kannada179
Chikkaballapura149
Mysuru107
Bagalkote103
Uttara Kannada95
Shivamogga67
Dharwad61
Ballari60
Gadag45
Bengaluru Rural40
Tumakuru36
Kolar29
Haveri24
Chikkamagaluru19
Chitradurga14
Koppal5
Kodagu4
Ramanagara3
Chamarajanagara0

10,55,040 6,955

61,672 3,569

9,80,519 3,350

12,849 36

DistrictCases
Chennai23,324
Chengalpattu1,314
Thiruvallur774
Villupuram509
Kanchipuram503
Tiruvannamalai496
Cuddalore477
Ariyalur444
Tirunelveli433
Tuticorin333
Kallakurichi324
Madurai322
Salem258
Coimbatore188
Virudhunagar185
Dindigul175
Perambalur133
Ranipet133
Thanjavur130
Theni129
Tiruchirappalli119
Ramanathapuram119
Tiruppur116
Kanniyakumari110
Tenkasi103
Nagapattinam99
Karur88
Namakkal83
Erode75
Vellore71
Thiruvarur67
Pudukkottai53
Sivaganga46
Tirupathur45
Krishnagiri43
The Nilgiris17
Dharmapuri15

9,26,816 5,989

37,673 4,014

8,76,257 1,952

12,886 23

DistrictCases
Kurnool795
Krishna557
Guntur511
Anantapur428
East Godavari356
Chittoor319
Sri Potti Sriramulu Nell*296
Y.S.R.205
West Godavari199
Srikakulam183
Prakasam104
Visakhapatnam103
Vizianagaram23

9,21,906 3,309

18,666 2,244

8,95,949 1,053

7,291 12

DistrictCases
North West5,463
Central4,817
West4,768
New Delhi3,405
North3,059
East2,472
South East2,446
South West2,391
South2,329
North East1,914
Shahdara1,580

7,14,423 7,897

28,773 2,142

6,74,415 5,716

11,235 39

DistrictCases
Gautam Buddha Nagar1,119
Agra933
Ghaziabad794
Meerut504
Lucknow386
Saharanpur298
Kanpur Nagar286
Moradabad252
Varanasi243
Hapur225
Aligarh215
Basti214
Amethi206
Rampur203
Jaunpur194
Firozabad190
Barabanki168
Gorakhpur166
Bulandshahr166
Siddharth Nagar159
Ghazipur159
Bijnor157
Deoria143
Azamgarh138
Sant Kabeer Nagar132
Mathura129
Ayodhya120
Muzaffarnagar117
Sambhal116
Sultanpur97
Ambedkar Nagar92
Maharajganj85
Amroha80
Rae Bareli78
Bahraich73
Kheri72
Kannauj69
Baghpat68
Kushi Nagar67
Bhadohi60
Ballia60
Gonda59
Etah52
Hardoi49
Balrampur49
Mau48
Mainpuri46
Etawah46
Hathras43
Unnao42
Jalaun41
Jhansi41
Shamli40
Chandauli38
Auraiya37
Farrukhabad36
Sitapur32
Prayagraj30
Banda27
Shahjahanpur25
Shravasti23
Budaun23
Mirzapur22
Bareilly17
Kasganj16
Pratapgarh15
Pilibhit15
Sonbhadra10
Kaushambi6
Kanpur Dehat4
Chitrakoot4
Lalitpur3
Hamirpur3
Mahoba3
Fatehpur3

6,76,739 12,748

58,801 10,495

6,08,853 2,207

9,085 46

DistrictCases
Kolkata2,777
Howrah1,435
24 Paraganas North1,031
Hooghly604
24 Paraganas South281
Maldah235
Dinajpur Uttar216
Coochbehar210
Birbhum206
Medinipur West159
Medinipur East153
Nadia139
Purba Bardhaman130
Murshidabad125
Bankura116
Darjeeling97
Jalpaiguri88
Paschim Bardhaman70
Purulia66
Dinajpur Dakshin50
Alipurduar39
Kalimpong18
Jhargram9

6,10,498 4,043

21,366 2,763

5,78,742 1,268

10,390 12

DistrictCases
Bilaspur100
Korba100
Mungeli87
Baloda Bazar85
Jashpur77
Janjgir-Champa56
Mahasamund54
Rajnandgaon52
Kabirdham52
Raigarh47
Raipur46
Balod41
Korea39
Durg31
Bemetara21
Kanker19
Balrampur17
Surguja14
Gariyaband10
Surajpur9
Dhamtari6
Bijapur2
Bastar2
Dantewada0
Kondagaon0
Narayanpur0
Sukma0

4,32,776 14,098

85,860 8,992

3,42,139 4,983

4,777 123

DistrictCases
Jaipur2,177
Jodhpur1,748
Udaipur724
Bharatpur563
Kota503
Nagaur500
Ajmer379
Dungarpur374
Pali352
Jhalawar329
Bhilwara250
Sikar231
Chittorgarh188
Tonk171
Jalore164
Rajsamand140
Sirohi130
Bikaner112
Banswara91
Alwar90
Churu81
Jhunjhunu64
Dausa61
Dholpur60
Baran59
Jaisalmer53
Barmer34
Hanumangarh31
SawaiMadhopur26
Karauli17
Pratapgarh14
Ganganagar8
Bundi5

3,58,688 4,401

27,906 3,821

3,27,866 562

2,916 18

DistrictCases
Ganjam581
Jajapur322
Khordha238
Baleshwar190
Kendrapara164
Cuttack155
Bhadrak137
Balangir129
Puri103
Sundargarh102
Jagatsinghapur91
Nayagarh86
Mayurbhanj73
Nuapada69
Gajapati61
Dhenkanal36
Boudh34
Kendujhar34
Deogarh33
Kalahandi33
Sonepur29
Kandhamal28
Anugul26
Malkangiri20
Bargarh16
Koraput16
Sambalpur16
Jharsuguda8
Nabarangpur2
Rayagada2

3,48,182 1,374

6,653 969

3,39,603 403

1,926 2

DistrictCases
Ahmadabad17,125
Surat2,311
Vadodara1,555
Gandhinagar410
Mahesana159
Banas Kantha147
Bhavnagar146
Rajkot135
Arvalli134
Mahisagar125
Anand107
PanchMahals107
Patan105
SabarKantha101
Kachchh99
Kheda98
Jamnagar63
Bharuch56
Botad55
Surendranagar55
Valsad47
GirSomnath45
Dohad43
Chhotaudepur37
Naysari35
Junagadh31
Narmada25
DevbhumiDwarka22
Amreli16
Porbandar11
Tapi6
Dang5
Morbi4

3,42,026 5,011

25,129 2,437

3,12,151 2,525

4,746 49

DistrictCases
Indore3,839
Bhopal1,880
Ujjain799
Burhanpur351
Neemuch319
Jabalpur276
East Nimar266
Sagar228
Gwalior211
Khargone196
Dewas140
Dhar132
Mandsaur112
Morena109
Bhind87
Raisen71
Barwani60
Ratlam51
Rewa39
Shajapur39
Hoshangabad37
Vidisha37
Chhatarpur35
Betul35
Rajgarh31
Dindori29
Sheopur26
Damoh26
Satna24
Anuppur22
Panna20
Tikamgarh18
Sidhi17
Narsinghpur17
Chhindwara16
Agar Malwa15
Mandla15
Shivpuri15
Jhabua14
Shandol14
Singrauli13
Ashoknagar13
Datia12
Sehore12
Umaria10
Balaghat9
Guna8
Harda4
Alirajpur3
Katni3
Seoni2
Niwari0

3,32,206 4,986

32,707 2,221

2,95,339 2,741

4,160 24

DistrictCases
Hyderabad2,475
Ranga Reddy183
Suryapet87
Jagitial77
Nizamabad76
MedchalMalkajgiri75
Mancherial43
YadadriBhuvanagiri40
Jogulamba Gadwal40
Vikarabad40
Nalgonda33
Warangal Urban32
Mahabubnagar30
Sangareddy26
Khammam26
Adilabad22
Nirmal21
Karimnagar17
RajannaSircilla16
Medak11
Kamareddy11
Mahabubabad10
Jayashankar Bhupalapally9
Nagarkurnool8
Kumuram Bheem Asifabad8
Jangoan8
Siddipet7
Peddapalli5
Bhadradri Kothagudem5
Warangal Rural4
Mulugu3
Narayanpet3
Wanaparthy1

3,27,278 3,187

20,184 2,393

3,05,335 787

1,759 7

DistrictCases
Gurugram2,950
Faridabad867
Sonipat404
Rohtak145
Palwal120
Jhajjar114
Karnal104
Hisar98
Ambala93
Panipat78
Nuh68
Bhiwani60
Rewari56
Kurukshetra55
Sirsa50
Kaithal48
Mahendragarh47
CharkiDadri43
Panchkula39
Fatehabad38
Jind38
Yamunanagar19

3,13,441 2,937

19,453 1,311

2,90,736 1,615

3,252 11

DistrictCases
Patna279
Bhagalpur266
Rohtas256
Khagaria253
Begusarai243
Madhubani199
Munger188
Jehanabad178
Katihar175
Darbhanga143
Samastipur139
Siwan139
PurbiChamparan138
Purnia135
Banka134
Buxar134
Nalanda123
Gopalganj123
Nawada122
Sheikhpura118
Gaya115
Kaimur (bhabua)105
Bhojpur103
Saran101
Muzaffarpur96
Saharsa88
Supaul87
Vaishali87
Madhepura82
Kishanganj75
Aurangabad75
Sitamarhi73
Lakhisarai72
Araria68
Pashchim Champaran57
Arwal52
Jamui47
Sheohar20

2,79,473 3,469

11,999 2,641

2,65,870 822

1,604 6

DistrictCases
Amritsar485
Jalandhar297
Ludhiana293
Tarn Taran163
Gurdaspur154
Hoshiarpur140
S.A.S Nagar137
Patiala132
Sangrur107
Shahid Bhagat Singh Nagar (Nawanshahr)99
Pathankot86
Rupnagar (Ropar)74
Faridkot74
Sri Muktsar Sahib71
Moga65
Bathinda60
Fatehgarh Sahib57
Fazilka53
Firozepur50
Kapurthala44
Mansa31
Barnala25

2,69,733 3,239

28,015 796

2,34,270 2,385

7,448 58

DistrictCases
Kamrup Metro276
Golaghat203
Nagaon143
Hojai89
Dima Hasao86
Karimganj85
Tinsukia84
Cachar80
Dibrugarh61
Hailakandi57
Lakhimpur57
Marigaon50
Dhemaji47
Kamrup42
Kokrajhar37
Dhubri30
Charaideo29
Barpeta28
Udalguri28
Sonitpur27
Jorhat24
Nalbari23
Darrang20
Sivasagar20
Goalpara19
Biswanath16
Baksa14
KarbiAnglong13
Bongaigaon12
Chirang6
West KarbiAnglong5
South SalmaraMancachar4
Majuli2

2,19,958 405

2,934 324

2,15,907 79

1,117 2

DistrictCases
Anantnag395
Srinagar300
Kulgam295
Baramulla271
Shopian255
Kupwara231
Bandipora175
Udhampur155
Ramban151
Jammu138
Budgam110
Pulwama108
Kathua53
Rajouri39
Ganderbal37
Poonch35
Doda27
Reasi26
Samba25
Kishtwar10
Mirpur0
Muzaffarabad0

1,37,475 1,005

6,755 640

1,28,691 359

2,029 6

DistrictCases
East Singhbum170
Ranchi148
Hazaribagh110
Garhwa80
Ramgarh75
Koderma58
Simdega48
Dhanbad32
Gumla28
Palamu27
West Singhbhum21
SaraikelaKharsawan20
Giridih19
Bokaro16
Latehar14
Khunti10
Lohardaga8
Deoghar5
Dumka5
Pakur4
Jamtara2
Godda2
Chatra1
Sahebganj0

1,37,088 2,373

12,293 1,689

1,23,603 667

1,192 17

DistrictCases
Dehradun370
Nainital323
Tehri Garhwal110
Haridwar94
Udam Singh Nagar83
Almora71
Champawat45
Pithoragarh43
Chamoli36
PauriGarhwal36
Bageshwar31
Rudraprayag30
Uttar Kashi24

1,07,479 1,233

6,241 857

99,486 373

1,752 3

DistrictCases
Hamirpur117
Kangra105
Una41
Solan32
Chamba29
Bilaspur21
Mandi21
Sirmaur11
Shimla10
Kullu4
Kinnaur2
Lahaul And Spiti0

69,114 941

5,223 564

62,776 365

1,115 12

DistrictCases
South Goa69
North Goa57

61,779 540

3,969 372

56,964 167

846 1

DistrictCases
Pondicherry111
Mahe4
Karaikal2
Yanam0

43,737 272

2,218 134

40,830 136

689 2

DistrictCases
Dhalai196
Sepahijala174
Gomati74
South Tripura53
Unakoti49
West Tripura45
Khowai24
North Tripura14

33,733 48

236 48

33,104

393

DistrictCases
Chandigarh313

30,341 398

3,265 52

26,680 343

396 3

DistrictCases
Churachandpur32
Kangpokpi26
Imphal West21
Thoubal18
Imphal East10
Tengnoupal9
Bishnupur7
Senapati6
Chandel5
Kamjong5
Ukhrul4
Jiribam3
Pherzawl3
Kakching2
Tamenglong2
Noney1

29,486 11

101 10

29,010 1

375

DistrictCases
Changlang31
Papum Pare8
Lohit3
Namsai2
West Siang1
East Siang1
Upper Siang1
Tawang1
PakkeKessang1
West Kameng0
Upper Subansiri0
Tirap0
Siang0
Shi Yomi0
Anjaw0
Lower Subansiri0
Lower Dibang Valley0
Longding0
Leparada0
KurungKumey0
KraDaadi0
Kamle0
East Kameng0
Dibang Valley0
Lower Siang0

16,878 3

32 2

16,790 1

56

DistrictCases
East Khasi Hills22
West Garo Hills5
South West Garo Hills4
North Garo Hills1
West Jaintia Hills1
West Khasi Hills1
East Garo Hills0
East Jaintia Hills0
Ribhoi0
South Garo Hills0
South West Khasi Hills0

14,246 39

202 35

13,893 4

151

DistrictCases
Dimapur20
Mon8
Kohima7
Kiphire3
Tuensang3
Peren2
Phek1
Longleng0
Mokokchung0
Wokha0
Zunheboto0

12,400 12

156 10

12,152 2

92

DistrictCases
Kargil77
LehLadakh43

10,765 146

611 54

10,023 91

131 1

DistrictCases
East District3
South District3
North District0
West District0

6,351 22

116 15

6,099 7

136

DistrictCases
South Andamans33
Nicobars1
North And Middle Andaman1

5,175 14

75 4

5,038 10

62

DistrictCases
Kolasib11
Aizawl10
Mamit8
Lawngtlai2
Lunglei2
Saitual1
Champhai0
Hnahthial0
Khawzawl0
Saiha0
Serchhip0

4,612 29

143 28

4,458 1

11

DistrictCases
Dadra And Nagar Haveli20

4,014 130

345 115

3,667 15

2

DistrictCases
Lakshadweep District0

794 10

60 5

733 5

1

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