South Korean health authorities raised new concerns about the novel coronavirus after reporting last month that dozens of patients who had recovered from the illness later tested positive again.
The findings suggested that some people who survived COVID-19 could become reinfected with the virus that causes it, potentially complicating efforts to lift quarantine restrictions and to produce a vaccine.
But after weeks of research, they now say that such test results appear to be "false positives" caused by lingering — but likely not infectious — bits of the virus.