I Tested Positive for Covid-19. What Does That Really Mean?

Michael Mina, an assistant professor of epidemiology at Harvard, believes there should be more focus on the so-called cycle threshold, the number of PCR amplification cycles required to produce a positive result. A high number of cycles suggests a low viral load. This may indicate that someone is at the beginning of an infection—or the end of one. If a person tests positive but is symptom-free, and a subsequent test shows a lower viral load, then they might not need to quarantine for as long. Public health experts increasingly are debating this idea. Some believe that a more nuanced picture could help control the spread of the disease by pinpointing the most infectious people and reducing the burden of quarantine for those who are not infectious. Others warn that the cycle threshold may not be a sufficiently reliable gauge of viral load, since it is influenced by the equipment, the chemistry, and the quality of the sample in each test.