Public-health specialists point to a few possible explanations for the success. Many schools adhered as best they could to guidance on mask-wearing, social distancing, contact tracing and quarantining. Given that adherence has been uneven, though, another likely reason is that young children don’t transmit the virus efficiently, said Eric Toner, senior scholar at the Johns Hopkins Center for Health Security.

Florida consistently has had lower rates of Covid-19 in schools than in the community at large, according to a data dashboard created by Brown University, data company Qualtrics and others. Available information allows them to track cases among students and staff at schools but not pinpoint whether infections occurred in schools or elsewhere.

In the last two weeks of February, the daily case rate per 100,000 people was 22 among students and 15 among school staff, compared with 27 in the community, according to the data. In earlier periods going back to October, the student and staff rates were almost always less than half the community rate.