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Infectiousness Peaks Earlier In COVID-19 Patients Than Thought, Study Says

According to the researchers, COVID-19 patients should self-isolate immediately after symptoms start because majority of transmissions occur during early stages especially within the first five days

Infectiousness Peaks Earlier In COVID-19 Patients Than Thought, Study Says
Highlights
  • The study shows why SARS-CoV-2 is so infectious: Expert
  • We need to raise awareness about the range of symptoms for COVID: Expert
  • More prominent COVID-19 symptoms are cough or fever: Scientist

London: People infected with the SARS-CoV-2 virus, that causes COVID-19, are most likely to be highly infectious in the first week after symptom onset, highlighting the need to identify and isolate cases early, according to a study. The research, published in The Lancet Microbe journal, says that although the genetic material of the novel coronavirus may still be detected in the respiratory or stool samples of COVID-19 patients for several weeks, no infectious virus particle was found beyond nine days of symptom onset.

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This is the first systematic review and meta-analysis that has comprehensively examined and compared viral load and shedding for these three human coronaviruses. It provides a clear explanation for why SARS-CoV-2 spreads more efficiently than SARS-CoV and MERS-CoV and is so much more difficult to contain, said study lead author Muge Cevik from the University of St Andrews in the UK.

According to the researchers, majority of viral transmission events occur very early, and especially within the first five days after symptom onset, indicating the importance of self-isolation immediately after symptoms start.

We also need to raise public awareness about the range of symptoms linked with the disease, including mild symptoms that may occur earlier on in the course of the infection than those that are more prominent like cough or fever, Mr. Cevik said.

In the research, the scientists specifically looked at people infected with SARS-CoV-2 and mainly those who were hospitalised. They said the results are only relevant for the period of self-isolation for people with confirmed COVID-19, and do not apply to people quarantining who may or may not have been exposed after contact with someone infected.

Also Read: Healthcare Workers, People Aged Above 65 Years Will Be Given COVID Vaccine On Priority: Dr. Harsh Vardhan

With many countries currently recommending that people with a SARS-CoV-2 infection should self-isolate for 10 days, the scientists said this is in line with their findings. They assessed key factors involved in the period of infectiousness of COVID-19 patients such as viral load, the length of time someone sheds viral genetic material (RNA) of the pathogen, and isolation of the live virus.

In their analysis, the researchers included 98 studies that had five or more participants, cohort studies and randomised controlled trials — 79 focussed on SARS-CoV-2, 73 of which included hospitalised patients only — eight on the 2002-03 SARS pandemic virus, and 11 on the MERS coronavirus infection. From these studies, the scientists calculated the average length of viral RNA shedding and examined the changes in viral load and the success of isolating the live virus from different samples collected throughout an infection.

The findings revealed that the average length of time of viral RNA shedding into the upper respiratory tract, lower respiratory tract, stool and serum were 17 days, 14.6 days, 17.2 days and 16.6 days, respectively.

These findings suggest that in clinical practice, repeat PCR testing may not be needed to deem that a patient is no longer infectious, as this could remain positive for much longer and does not necessarily indicate they could pass on the virus to others. In patients with non-severe symptoms, their period of infectiousness could instead be counted as 10 days from symptom onset, Mr. Cevik said.

Also Read: ‘How Smoking Worsens COVID-19 Infection Decoded’: Scientists

The study noted that the highest viral load of SARS-CoV-2 RNA were detected early in the course of the disease — at the time symptoms begin, or before day five of symptoms. Asymptomatic infection may clear the virus faster, the researchers said, suggesting that those without symptoms may be as infectious as those with symptoms at the beginning of infection, but may remain so for a shorter period.

However, Mr. Cevik added that there are limited data available on the shedding of infectious virus in asymptomatic individuals to inform any policy change on quarantine duration in the absence of testing. Citing the limitations of the research, the scientists said many of the patients across the different studies included in the analysis were hospitalised and received a range of treatments that may affect the course of their infection. They said the studies included different populations who were followed up and managed differently.

The period of infectiousness may also not exactly align with the successful culturing of the live virus from samples, although these are likely to broadly overlap, the scientists added. “The majority of studies included in our review were performed in patients who were admitted to hospital. Therefore, our findings may not apply to people with milder infection although these results suggest those with milder cases may clear the virus faster from their body,” said study senior author Antonia Ho of MRC-University of Glasgow Centre for Virus Research in the UK.

Also Read: COVID-19: Indiscriminate Use Of Convalescent Plasma Therapy Not Advisable, Says ICMR

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

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

26,27,61,966Cases
22,35,18,265Active
3,40,28,506Recovered
52,15,195Deaths
Coronavirus has spread to 196 countries. The total confirmed cases worldwide are 26,27,61,966 and 52,15,195 have died; 22,35,18,265 are active cases and 3,40,28,506 have recovered as on December 1, 2021 at 3:56 am.

India

3,45,96,776 8,954Cases
99,0231,520Active
3,40,28,506 10,207Recovered
4,69,247 267Deaths
In India, there are 3,45,96,776 confirmed cases including 4,69,247 deaths. The number of active cases is 99,023 and 3,40,28,506 have recovered as on December 1, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths
Maharashtra

66,35,658 678

11,226 299

64,83,435 942

1,40,997 35

Kerala

51,41,814 4,723

44,314 824

50,57,368 5,370

40,132 177

Karnataka

29,96,148 291

6,445 462

29,51,492 745

38,211 8

Tamil Nadu

27,26,917 720

8,244 47

26,82,192 758

36,481 9

Andhra Pradesh

20,72,909 184

2,149 47

20,56,318 134

14,442 3

Uttar Pradesh

17,10,399 12

89 3

16,87,399 8

22,911 1

West Bengal

16,16,083 705

7,731 2

15,88,866 694

19,486 13

Delhi

14,40,934 34

287 2

14,15,549 32

25,098

Odisha

10,49,108 228

2,188 23

10,38,509 203

8,411 2

Chhattisgarh

10,06,813 34

318 0

9,92,902 34

13,593

Rajasthan

9,54,785 15

193 6

9,45,637 9

8,955

Gujarat

8,27,475 40

275 13

8,17,108 27

10,092

Madhya Pradesh

7,93,170 20

119 7

7,82,523 27

10,528

Haryana

7,71,709 17

163 2

7,61,492 19

10,054

Bihar

7,26,223 4

36 3

7,16,524 7

9,663

Telangana

6,75,994 196

3,591 10

6,68,411 184

3,992 2

Assam

6,16,852 144

2,625 30

6,08,124 109

6,103 5

Punjab

6,03,279 21

325 4

5,86,352 22

16,602 3

Jharkhand

3,49,244 12

98 3

3,44,006 9

5,140

Uttarakhand

3,44,255 28

141 9

3,36,706 19

7,408

Jammu And Kashmir

3,36,852 171

1,625 1

3,30,751 172

4,476

Himachal Pradesh

2,27,195 102

834 10

2,22,513 91

3,848 1

Goa

1,78,928 38

284 8

1,75,260 30

3,384

Mizoram

1,35,175 365

3,751 54

1,30,927 415

497 4

Puducherry

1,28,924 31

284 12

1,26,768 43

1,872

Manipur

1,25,205 36

649 6

1,22,579 40

1,977 2

Tripura

84,805 14

81 3

83,900 10

824 1

Meghalaya

84,480 19

294 9

82,713 9

1,473 1

Chandigarh

65,465 9

65 7

64,580 2

820

Arunachal Pradesh

55,276 3

35 0

54,961 3

280

Sikkim

32,242 9

124 3

31,715 6

403

Nagaland

32,122 13

133 7

31,293 20

696

Ladakh

21,578 38

276 26

21,088 12

214

Dadra And Nagar Haveli

10,683

1 0

10,678

4

Lakshadweep

10,394

24 0

10,319

51

Andaman And Nicobar Islands

7,683

6 2

7,548 2

129

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