A study by researchers in South Korea last month suggested that children ages 10-19 spread the coronavirus more frequently than adults — a widely reported finding that influenced the debate about the risks of reopening schools.

But additional data from the research team now calls that conclusion into question; it is not clear who was infecting whom. The incident underscores the need to consider the preponderance of evidence, rather than any single study, when making decisions about children’s health or education, scientists said.

Some of the household members who appeared in the initial report to have been infected by older children in fact were exposed to the virus at the same time as the children. All of them may have been infected by contacts they shared.