CNN  — 

Closing schools for eight weeks or more may have a greater impact on mitigating the spread of the novel coronavirus than two- to four-week closures, the US Centers for Disease Control and Prevention has said.

Shorter-term closures will likely make little difference in the spread of the disease, new CDC guidance states, even as K-12 school districts across the country began announcing school closures within the shorter time frame.

Further, short-term closures may actually have detrimental effects, negatively impacting older caregivers at home, the CDC said.

Closing schools also comes with its own setbacks, namely a potentially negative impact on academic outcomes, which the CDC also acknowledged in its updated guidelines. The Department of Education recently issued its own guidance to educators about its flexibility related to student absences and testing standards.

In any school closure, students could still congregate outside of school and spread the disease, the CDC acknowledged.

Other mitigation efforts, including handwashing and home isolation, “have more impact on (the) spread of disease,” the new CDC guidance states.

“In other countries, those places who closed school … have not had more success in reducing spread than those that did not,” the CDC said, offering as examples Hong Kong and Singapore, respectively.

Some American colleges and universities have issued indefinite campus closures, with courses moving online and dorms shut down entirely.