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

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 |