Coronavirus Antibodies May Last for at Least 4 Months, New Study Finds

Researchers noted that it is still unclear whether antibodies protect people from reinfection

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A new study has found that antibodies from the novel coronavirus (COVID-19) may last for at least four months after a person gets infected.

The study, published Tuesday in The New England Journal of Medicine, measured antibodies from 30,576 people in Iceland. Researchers found that COVID-19 antibodies did not decline within four months after patients were first diagnosed with the virus.

"There is no evidence of any slight decrease," study co-author Dr. Kári Stefánsson told Today, adding antibodies were also found in asymptomatic people who were never tested for coronavirus.

Researchers also observed higher levels of antibodies in older patients and in people who were hospitalized with a more severe case of coronavirus. Women, smokers and users of anti-inflammatory medication had lower levels of antibodies.

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However, a connection between having COVID-19 antibodies and being immune to reinfection “has yet to be established in humans,” the study says.

"What they're seeing here is that they're inducing a pretty strong immune response," Jason Kindrachuk, an assistant professor of medical microbiology & infectious diseases at the University of Manitoba in Winnipeg — who was not involved in the study — told Today.

"What we don't know is really the million-dollar question: How do these antibodies reflect immunity against this virus and inhibition of this virus," Kindrachuk added. "Just because you see antibodies being produced, it doesn't tell you that those antibodies are going to act specifically against the virus."

Last week, researchers announced the first confirmed case of coronavirus reinfection in a 33-year-old man in Hong Kong.

The man had first tested positive for COVID-19 in Hong Kong in late March and had mild symptoms. The second time, he tested positive after returning from a trip to Spain but was asymptomatic.

The researchers confirmed that the man had contracted COVID-19 twice and was not just experiencing a lingering case of the virus, as others have, by looking at the sequencing of the virus strains. The sequencing of his second case of COVID-19 matched the virus strains that have been circulating in Europe in July and August.

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