Scientists from the Korean Centers for Disease Control and Prevention studied 285 Covid-19 survivors who had tested positive for the novel coronavirus again after recovery. The re-positive patients weren't found to have spread any lingering infection, and virus samples collected from them couldn't be grown in culture, indicating that the patients were shedding non-infectious or dead virus particles, the research said. This may aid in the debate over antibody tests. Experts believe that antibodies probably convey some level of protection against the virus, but they don't have any solid proof yet. As a result of the findings, authorities in South Korea said that people should no longer be required to test negative for the virus before returning to work or school after they have recovered from their illness and completed their isolation period.