Revealing S. Korean studies show antibodies could thwart COVID-19 reinfection, spread It's still unclear how long antibodies last in people who have recovered.

Results from two new South Korean studies shed light on whether antibodies will be a reliable form of protection against COVID-19 for those who have recovered from the disease.

In one ongoing study, the Korean Center for Disease Control found that 100% of 25 randomly selected patients who were hospitalized with symptoms and who fully recovered, developed defensive antibodies against COVID-19.

Researchers were initially concerned that antibodies might not kill the virus, because roughly half of patients had both antibodies and a current COVID-19 infection.

Further investigation, however, suggested that the virus scientists detected might have been dead or so weak that it couldn't infect others.

In a second study of more than 10,700 COVID-19 patients, researchers examined 207 individuals who were re-diagnosed with COVID-19 after recovering from their infections.

In 39 of those 207 re-diagnosed individuals, researchers did not find any virus replication in patient samples they analyzed.

In other words, the new research suggests that if a patient is re-diagnosed with COVID-19 after recovering, it's unlikely he or she will be able to infect others.

Still, the KCDC cautioned, it's unclear how long those antibodies last. Until we have that key piece of data, the jury is still out on whether mass immunity is possible.

ABC News' Joohee Cho contributed to this report.

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