Mild COVID-19 Induces Lasting Antibody Protection, Study Finds | News

May 25, 2021 0 Comments



People who have had mild illness during COVID-19 develop antibody-producing cells that can last lifetime

Highlights
  • Antibody-producing cells found 11 months after first symptoms: Expert
  • It’s normal for antibody levels to go down after acute infection: Expert
  • During viral infection, antibody-producing immune cells rapidly multiply

New Delhi: Months after recovering from mild cases of COVID-19, people still have immune cells which produce antibodies against the novel coronavirus, according to a study. The researchers from Washington University School of Medicine in St. Louis, US, noted that such cells could persist for a lifetime, churning out antibodies all the while.

The study, published on Monday (May 14) in the journal Nature, suggests that mild cases of COVID-19 leave those infected with lasting antibody protection and that repeated bouts of illness are likely to be uncommon.

Last fall, there were reports that antibodies wane quickly after infection with the virus that causes COVID-19, and mainstream media interpreted that to mean that immunity was not long-lived. But that’s a misinterpretation of the data. It’s normal for antibody levels to go down after acute infection, but they don’t go down to zero; they plateau, said senior author of the study Ali Ellebedy, an associate professor at Washington University School of Medicine.

The researchers found antibody-producing cells in people 11 months after first symptoms. These cells will live and produce antibodies for the rest of people’s lives, and that’s strong evidence for long-lasting immunity, they said.

Also Read: COVID-19 In India: Experts Say Pregnant Women At Greater Risk In The Second Wave Of COVID-19

During a viral infection, antibody-producing immune cells rapidly multiply and circulate in the blood, driving antibody levels sky-high. Once the infection is resolved, most such cells die off, and blood antibody levels drop. A small population of antibody-producing cells, called long-lived plasma cells, migrate to the bone marrow and settle in, the researchers said. In the bone marrow, these cells continually secrete low levels of antibodies into the bloodstream to help guard against another encounter with the virus, they said.

Mr. Ellebedy and colleagues were already working on a project to track antibody levels in blood samples from COVID-19 survivors. The team had enrolled 77 participants who were giving blood samples at three-month intervals starting about a month after initial infection. Most participants had had mild cases of COVID-19, only six had been hospitalised.

The researchers obtained bone marrow from 18 of the participants seven or eight months after their initial infections. Five of them came back four months later and provided a second bone marrow sample. For comparison, the scientists also obtained bone marrow from 11 people who had never had COVID-19.

They found that antibody levels in the blood of the COVID-19 participants dropped quickly in the first few months after infection and then mostly levelled off, with some antibodies detectable even 11 months after infection. Fifteen of the 19 bone marrow samples from people who had had COVID-19 contained antibody-producing cells specifically targeting the virus that causes COVID-19, the researchers said. Such cells could still be found four months later in the five people who came back to provide a second bone-marrow sample, they said.

According to the researchers, none of the 11 people who had never had COVID-19 had such antibody-producing cells in their bone marrow.

People with mild cases of COVID-19 clear the virus from their bodies two to three weeks after infection, so there would be no virus driving an active immune response seven or 11 months after infection. These cells are not dividing. They are quiescent, just sitting in the bone marrow and secreting antibodies. They have been doing that ever since the infection resolved, and they will continue doing that indefinitely, Mr. Ellebedy said.

Also Read: COVID-19 Could Become Like Common Cold In Future, Study Suggests

(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

16,73,12,761Cases

5,95,95,549Active

10,42,44,112Recovered

34,73,100Deaths

Coronavirus has spread to 192 countries. The total confirmed cases worldwide are 16,73,12,761 and 34,73,100 have died; 5,95,95,549 are active cases and 10,42,44,112 have recovered as on May 25, 2021 at 4:14 am.

India

2,69,48,874 1,96,427Cases

25,86,7821,33,934Active

2,40,54,861 3,26,850Recovered

3,07,231 3,511Deaths

In India, there are 2,69,48,874 confirmed cases including 3,07,231 deaths. The number of active cases is 25,86,782 and 2,40,54,861 have recovered as on May 25, 2021 at 2:30 am.

State Details

State Cases Active Recovered Deaths
Maharashtra

56,02,019 22,122

3,30,215 20,790

51,82,592 42,320

89,212 592

Karnataka

24,50,215 25,311

4,40,456 32,551

19,83,948 57,333

25,811 529

Kerala

23,65,787 17,821

2,59,559 18,414

20,98,674 36,039

7,554 196

Tamil Nadu

18,77,211 34,867

3,01,580 7,437

15,54,759 27,026

20,872 404

Uttar Pradesh

16,73,785 3,894

76,703 8,177

15,77,720 11,918

19,362 153

Andhra Pradesh

15,93,821 12,994

2,03,762 5,475

13,79,837 18,373

10,222 96

Delhi

14,18,418 1,550

24,578 3,032

13,70,431 4,375

23,409 207

West Bengal

12,84,973 17,883

1,28,585 1,940

11,41,871 19,670

14,517 153

Chhattisgarh

9,53,209 4,209

60,938 4,836

8,79,625 8,985

12,646 60

Rajasthan

9,20,456 4,414

99,875 12,343

8,12,775 16,654

7,806 103

Gujarat

7,91,657 3,187

68,971 6,163

7,13,065 9,305

9,621 45

Madhya Pradesh

7,67,274 2,936

53,653 4,113

7,06,003 6,989

7,618 60

Haryana

7,41,785 3,757

38,119 4,697

6,96,059 8,359

7,607 95

Odisha

7,03,441 11,059

99,701 587

6,01,224 11,614

2,516 32

Bihar

6,92,420 2,844

37,943 2,749

6,49,835 5,500

4,642 93

Telangana

5,56,320 3,043

39,206 1,283

5,13,968 4,305

3,146 21

Punjab

5,43,475 4,481

54,996 2,509

4,75,011 6,803

13,468 187

Assam

3,75,404 6,221

53,996 885

3,18,585 5,252

2,823 84

Jharkhand

3,31,811 1,394

17,569 1,930

3,09,371 3,291

4,871 33

Uttarakhand

3,15,590 2,071

49,579 5,156

2,60,084 7,105

5,927 122

Jammu And Kashmir

2,72,858 2,237

45,630 1,807

2,23,619 3,999

3,609 45

Himachal Pradesh

1,80,983 1,949

24,181 1,798

1,53,975 3,686

2,827 61

Goa

1,47,861 1,401

16,278 999

1,29,162 2,362

2,421 38

Puducherry

96,982 922

15,835 1,016

79,765 1,915

1,382 23

Chandigarh

58,734 245

4,428 446

53,597 684

709 7

Tripura

47,298 773

8,302 341

38,526 427

470 5

Manipur

44,627 538

6,444 90

37,478 611

705 17

Meghalaya

30,492 811

7,788 108

22,221 679

483 24

Arunachal Pradesh

24,573 480

3,127 228

21,344 248

102 4

Nagaland

20,259 191

4,714 36

15,248 143

297 12

Ladakh

17,532 125

1,463 59

15,891 184

178

Sikkim

13,233 101

3,184 133

9,817 226

232 8

Mizoram

10,622 289

2,569 108

8,019 180

34 1

Dadra And Nagar Haveli

10,049 62

439 82

9,606 144

4

Andaman And Nicobar Islands

6,853 9

254 14

6,495 22

104 1

Lakshadweep

6,847 236

2,162 112

4,661 124

24





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