Many parents in the U.S. have tough questions about the vaccines for young children.

It’s a moment many parents have anxiously awaited for months: Children younger than age 5 are now eligible for vaccination against the coronavirus, among the last Americans to qualify.

Without access to vaccines, parents of young children have confronted nearly impossible choices since the pandemic began. Many children were kept from schools, family gatherings and other activities, and deprived of normal childhood experiences. Now all that could change.

On Saturday, the Centers for Disease Control and Prevention recommended the Moderna and Pfizer-BioNTech vaccines for children as young as 6 months. The decision means shots will be administered for the first time to these young children, perhaps as early as Tuesday.

Sunny Baker, 35, a mother of two in Oxford, Miss., said she vaccinated her older daughter, Hattie Ruth, 5, at the first chance, and has been eagerly waiting for her 2-year-old daughter, Alma Pearl, to qualify.

“Yes, yes, yes! We would love to be first in line,” she said.

But Ms. Baker may very well be in the minority: A recent Kaiser Health poll found that only one in five parents will get their young children vaccinated immediately. Many plan to hold off for now.

As the pandemic stretches into a third year and Americans weigh the risks they are willing to live with, the C.D.C.’s decision puts parents of young children on the spot.

Vaccines have lost some of their potency against infection with new variants, though they continue to offer protection against severe illness and death. And huge numbers of Americans were infected during the Omicron surge, contributing to a mistaken sense among many that the battle was over.

Shifting advice has also contributed to a lack of enthusiasm. Daryl Richardson, 37, of Baltimore, said he had no plans to vaccinate his three children, in part because of the constant changes to the number of doses recommended.

“First it was one shot, and then it was a booster, and another booster,” he said.

After navigating the perils of the pandemic with their children for so long, parents now face new questions, some so complex they have stumped even regulators and experts. Which vaccine is better? How well, and how soon, will they work? And why bother, if the majority of young children have already been exposed to the virus?

Both the Pfizer-BioNTech and Moderna shots are considered safe for young children, and both yield blood levels of protective antibodies similar to those seen in young adults. But neither delivers the miraculous protection provided by the adult vaccines in the pandemic’s early days.