COVID-19 immunity following a confirmed infection can linger for at least five months, according to a new study.
CNN reports that researchers also suspect it may extend even longer than that.
Despite previous reports documenting individuals getting sick with COVID-19 more than once, implying a lack of antibody immunity, the human body has different reactions to a virus. The report documented that about 90 percent of people who recover from COVID-19 maintain a stable antibody count rather than see them die off.
The study — published in the journal Science — featured antibody responses sampled from more than 30,000 patients diagnosed with COVID-19 within the Mount Sinai Health System between March and October. When analyzing antibody responses, researchers classified the strength as low, moderate, or high.
More than 90 percent produced moderate to high levels of antibodies that attach to the virus cells.
“While some reports have come out saying antibodies to this virus go away quickly, we have found just the opposite — that more than 90% of people who were mildly or moderately ill produce an antibody response strong enough to neutralize the virus, and the response is maintained for many months,” said Florian Krammer, a professor of vaccinology at the Icahn School of Medicine at Mount Sinai. Krammer was one of the lead researchers on the study.
During the study, scientists then examined 121 patients who ultimately donated their plasma following recovery. They looked at the plasma three months after the patients first developed symptoms, and again in another five months.
While the total antibody count fell, others remained.
“The sustained antibody levels that we subsequently observed are likely produced by long-lived plasma cells in the bone marrow,” Ania Wajnberg, the director of Clinical Antibody Testing at Mount Sinai, said. “This is similar to what we see in other viruses and likely means they are here to stay. We will continue to follow this group over time to see if these levels remain stable as we suspect and hope they will.”
Wajnberg also said that the antibody volume measured was probably produced by plasmablasts, which act as the first line of defense to an invading virus. Over time, their strength fades, giving way to more sustainable antibodies.
The results, while interesting, do not conclusively say whether or not a coronavirus infection can protect recovered patients.
“Although this cannot provide conclusive evidence that these antibody responses protect from reinfection, we believe it is very likely that they will decrease the odds ratio of reinfection,” the report read.
Researchers said moving forward in learning about COVID-19, they will look at correlates of protection, which are measurable signs derived from blood testing that will tell doctors if someone is immune.