Mild COVID-19 Leaves Infected Patients With Lasting Antibody, Making Reinfection Uncommon
(Photo : Wikimedia Commons) COVID-19 antibody testing of all journalists and photographers

Developing antibodies after getting COVID-19 is an expected response of the body. But many would ask how long these antibodies will last and whether being infected once guarantees not being infected again.

Previous studies suggest that those who recover from COVID-19 could produce antibodies that will last for at least six months or longer.

Now, a new study by researchers from the Washington University School of Medicine at St. Louis claims that mild cases of COVID-19 could have immune cells that churn out antibodies that could persist for a lifetime. That means it could protect against reinfection.

They published the findings of their study, "SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans," in the journal Nature.

 Mild COVID-19 Leaves Infected Patients With Lasting Antibody, Making Reinfection Uncommon
(Photo: Wikimedia Commons)
COVID-19 antibody testing of all journalists and photographers

COVID-19 Antibodies Level Could Go Down

Study senior author Ali Ellebedy, Ph.D. said that the data presented in the reports from previous months that antibodies wane quickly after the infection was misinterpreted, Medical Xpress reported.

He noted that it is normal for antibody levels to go down after an acute infection. However, that does not mean that it will completely go down to zero. Instead, antibody levels will only plateau or remain at a certain level.

Referring to patients who recovered from mild cases of COVID-19 after 11 months, he said that antibodies found will live and continue to produce antibodies for the rest of the patient's life. It is strong evidence that antibodies could last long.

Immune cells produce antibodies that rapidly multiply and circulate in the blood that drives antibody levels sky-high. But it drops after the infection is resolved.

On the other hand, a small population of plasma cells that produce antibodies continues to secrete low levels of antibodies into the bloodstream to provide adequate protection against the virus in case it encounters it again.

According to Science Daily, the immune system remembers foreign bodies, such as viruses, and improves its quality of antibodies even after the infection waned. Antibodies that are produced after a few months were observed to have an increased ability against the SARS-CoV-2 virus and its mutated versions, like the South African variant.

Ellebedy realized that the key to figuring out whether COVID-19 leads to long-lasting protection is in the bone marrow. They obtained bone marrow from patients who recovered from mild COVID-19 to see whether they harbor plasma cells that produce antibodies. They found that such cells could be found in the patients even after months since their recovery.

ALSO READ: More Newborns Have Detectable Levels of COVID-19 Antibodies

Asymptomatic COVID-19 Patients May Also Have Long-Lasting Antibodies

News Medical Life Sciences reported asymptomatic COVID-19 patients to lose their IgG antibodies more often and rapidly compared to symptomatic patients regardless of their sex, age, and body weight.

However, Medical Xpress reported that Ellebedy's team speculated that even asymptomatic patients may also be left with long-lasting immunity. He added that further study is also needed in determining whether those with severe cases would also have long-lasting immunity against reinfection.

The first author of the study, Jackson Turner, Ph.D., said that it could either lead to defective immune responses or could have good immune responses due to having lots of viruses in the body. As of now, it is not clear yet and more research on moderate to severe infections is needed to understand if it protects patients from future reinfection.

The team is now studying whether vaccines could also induce long-lived antibodies.

 RELATED ARTICLE: Asymptomatic COVID-19 Patients May Lose Antibodies Sooner Than Those With Symptoms

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