As vaccines for younger U.S. children roll out, the effects on day care centers may be muted.

The American Academy of Pediatrics and other health care experts strongly recommend that all children ages 6 months and older get vaccinated. The Centers for Disease Control and Prevention recently noted as well that “All children, including children who have already had Covid-19, should get vaccinated.”

“For kids who are vaccinated, these vaccines will make it even less likely that they will get severe illness, but they will also make it less likely for them to be infected in the first place and to pass on the virus to other kids and to adults who might be susceptible to more severe illness,” said Crystal Watson, a senior scholar at the Johns Hopkins Center for Health Security at the Bloomberg School of Public Health.

Another challenge is the patchwork of guidelines from county and state governments, with their array of isolation and quarantine requirements for infected children and their close contacts. Child care centers vary widely in their protocols, Dr. Watson said, and many would not make changes unless there were updated guidance from the Centers for Disease Control and Prevention, or state and local health departments.

“The regulations are inconsistent and their interpretation is inconsistent,” said Gigi Schweikert, the chief executive of Lightbridge Academy, which operates 120 early childhood care centers across the country. Lightbridge does not plan to require children be vaccinated unless state or local health departments do.

“What we’re hoping will happen is that if children are vaccinated and asymptomatic and have been in an exposure situation, they will not be asked to quarantine,” she said.

Many are hoping for a more significant impact from the new authorizations. Kristie Skoglund, the chief executive of the Florida Center for Early Childhood, which provides care and therapy for young children with developmental delays, disabilities and mental health challenges, said that the vaccines will help organizations like hers by providing another preventive tool that “may help the transition back to prepandemic policies and procedures.”

Jesus Jiménez, Amanda Holpuch, Alexandra E. Petri, and Carly Olson contributed reporting.