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Coronavirus Circulated Undetected Months Before First COVID-19 Cases In China: Study

China had officially reported the first cases of the novel coronavirus disease in mid-December and the outbreak in Wuhan city of Hubei province was reported to the WHO on December 31, 2019

Coronavirus Circulated Undetected Months Before First COVID-19 Cases In China: Study
Highlights
  • China enforced a lockdown in Wuhan and other cities in April 2020
  • COVID-19 had spread to over 100 countries by April, 2020: Expert
  • WHO declared COVID-19 as a pandemic on March 11, 2020

Washington: The novel coronavirus was likely circulating undetected for at most two months before the first human cases of COVID-19 were described in Wuhan, China in late-December 2019, according to a study. The research, published in the journal Science, used molecular dating tools and epidemiological simulations to date the emergence of the virus to as early as October 2019. The team, including researchers from University of California San Diego in the US, note that their simulations suggest that the mutating virus dies out naturally more than three-quarters of the time without causing an epidemic.

Also Read: Analysis Shows Children Between 0-14 Years Less Affected By COVID: Government

Senior study author Joel O Wertheim, an associate professor at UC San Diego School of Medicine said,

Our study was designed to answer the question of how long could SARS-CoV-2 have circulated in China before it was discovered. To answer this question, we combined three important pieces of information: a detailed understanding of how SARS-CoV-2 spread in Wuhan before the lockdown, the genetic diversity of the virus in China and reports of the earliest cases of COVID-19 in China.

By combining these disparate lines of evidence, the researchers were able to put an upper limit of mid-October 2019 for when SARS-CoV-2 started circulating in Hubei province. Cases of COVID-19 were first reported in late-December 2019 in Wuhan, located in the Hubei province of central China.

The researchers used molecular clock evolutionary analyses to try to home in on when the first, or index, case of SARS-CoV-2 occurred. “Molecular clock” is a term for a technique that uses the mutation rate of genes to deduce when two or more life forms diverged — in this case, when the common ancestor of all variants of SARS-CoV-2 existed, estimated in this study to as early as mid-November 2019.

Molecular dating of the most recent common ancestor is often taken to be synonymous with the index case of an emerging disease.

The index case can conceivably predate the common ancestor — the actual first case of this outbreak may have occurred days, weeks or even many months before the estimated common ancestor. Determining the length of that ‘phylogenetic fuse’ was at the heart of our investigation, said study co-author Michael Worobey, a professor at the University of Arizona.

Also Read: COVID-19 Affected Health Condition Of 26 Per Cent Elderly People In India: Study

Based on this work, the researchers estimate that the median number of persons infected with SARS-CoV-2 in China was less than one until November 4, 2019. Thirteen days later, it was four individuals, and just nine on December 1, 2019, they said. The first hospitalisations in Wuhan with a condition later identified as COVID-19 occurred in mid-December.

The researchers used a variety of analytical tools to model how the SARS-CoV-2 virus may have behaved during the initial outbreak and early days of the pandemic when it was largely an unknown entity.

These tools included epidemic simulations based on the virus’s known biology, such as its transmissibility and other factors. In just 29.7 per cent of these simulations was the virus able to create self-sustaining epidemics. In the other 70.3 per cent, the virus infected relatively few persons before dying out. The average failed epidemic ended just eight days after the index case.

We saw that over two-thirds of the epidemics we attempted to simulate went extinct. That means that if we could go back in time and repeat 2019 one hundred times, two out of three times, COVID-19 would have fizzled out on its own without igniting a pandemic. This finding supports the notion that humans are constantly being bombarded with zoonotic pathogens, he added.

Also Read: 100-Year-Old Woman Gets First Dose Of COVID-19 Vaccine In Delhi

(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

26,06,51,261Cases
22,14,73,133Active
3,39,88,797Recovered
51,89,331Deaths
Coronavirus has spread to 196 countries. The total confirmed cases worldwide are 26,06,51,261 and 51,89,331 have died; 22,14,73,133 are active cases and 3,39,88,797 have recovered as on November 27, 2021 at 4:06 am.

India

3,45,63,749 8,318Cases
1,07,0193,114Active
3,39,88,797 10,967Recovered
4,67,933 465Deaths
In India, there are 3,45,63,749 confirmed cases including 4,67,933 deaths. The number of active cases is 1,07,019 and 3,39,88,797 have recovered as on November 27, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths
Maharashtra

66,33,105

12,153 699

64,80,061 665

1,40,891 34

Kerala

51,24,618 4,677

50,109 2,343

50,35,384 6,632

39,125 388

Karnataka

29,94,963 402

6,640 119

29,50,130 277

38,193 6

Tamil Nadu

27,23,991 746

8,418 24

26,79,130 759

36,443 11

Andhra Pradesh

20,72,198 184

2,163 31

20,55,603 214

14,432 1

Uttar Pradesh

17,10,368 8

91 0

16,87,368 8

22,909

West Bengal

16,13,451 710

7,847 20

15,86,165 721

19,439 9

Delhi

14,40,807 23

301 8

14,15,411 31

25,095

Odisha

10,48,228 219

2,216 5

10,37,609 222

8,403 2

Chhattisgarh

10,06,706 33

319 7

9,92,794 26

13,593

Rajasthan

9,54,715 21

174 19

9,45,586 2

8,955

Gujarat

8,27,354 27

308 7

8,16,954 34

10,092

Madhya Pradesh

7,93,097 9

103 1

7,82,466 8

10,528

Haryana

7,71,643 21

158 2

7,61,431 19

10,054

Bihar

7,26,209 5

45 1

7,16,501 6

9,663

Telangana

6,75,319 171

3,534 3

6,67,798 167

3,987 1

Assam

6,16,312 175

2,791 44

6,07,435 219

6,086

Punjab

6,03,173 41

335 21

5,86,245 18

16,593 2

Jharkhand

3,49,196 12

109 0

3,43,947 12

5,140

Uttarakhand

3,44,169 13

144 13

3,36,618 26

7,407

Jammu And Kashmir

3,36,237 174

1,719 13

3,30,048 157

4,470 4

Himachal Pradesh

2,26,859 102

827 8

2,22,190 107

3,842 3

Goa

1,78,799 34

266 11

1,75,152 22

3,381 1

Mizoram

1,33,921 359

4,227 111

1,29,206 469

488 1

Puducherry

1,28,825 31

321 3

1,26,632 28

1,872

Manipur

1,25,098 28

674 13

1,22,456 39

1,968 2

Tripura

84,771 10

80 4

83,871 6

820

Meghalaya

84,394 16

335 4

82,591 20

1,468

Chandigarh

65,438 8

48 7

64,570 1

820

Arunachal Pradesh

55,260 2

33 1

54,947 3

280

Sikkim

32,207 9

119 6

31,685 15

403

Nagaland

32,096 4

136 5

31,264 9

696

Ladakh

21,467 32

243 8

21,011 24

213

Dadra And Nagar Haveli

10,683

1 0

10,678

4

Lakshadweep

10,394 11

29 11

10,314

51

Andaman And Nicobar Islands

7,678 1

3 0

7,546 1

129

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