For American parents, particularly those with young children, the last couple of months have been dizzying and beyond frustrating.

In early February, federal regulators announced that they would evaluate Pfizer-BioNTech’s coronavirus vaccine for the youngest children — only to scrap that plan 10 days later, citing doubts about the vaccine’s effectiveness in that age group.

Soon after, scientists reported that the vaccine was only weakly protective against infection with the Omicron variant among children aged 5 to 11 and that it appeared to offer little defense against moderate Covid illness among adolescents aged 12 to 17.

On Monday, citing these data, Florida’s surgeon general declared that healthy children need not be immunized, advice that Jen Psaki, the White House press secretary, called “deeply disturbing.”

Through it all, experts have continued to endorse vaccines, noting that while the Omicron variant may be able to penetrate immune defenses and infect people, the vaccines still prevent severe illness and death — and may do so for years.

The Centers for Disease Control and Prevention found that record numbers of children under 5 had been hospitalized during the Omicron surge, underscoring the need for vaccines for those children. But the agency has since said that 90 percent of Americans can safely stop wearing masks in public indoor spaces, even in schools with young children.

Who could blame parents for feeling bewildered?

“The part that’s confusing is like there’s no longer any clear, right answer,” said Anne Gonzalez, a 41-year-old mother of two who manages volunteers for a large religious nonprofit in St. Louis. “I’ve come to the point that all I can do is what I think is right for my family.”

Fortunately, the coming weeks should bring some clarity. Both Pfizer and Moderna plan to report results from trials of their vaccines in young children. The results, if positive, should lead to a new round of regulatory review, perhaps as early as April, that may well allow vaccinations for tens of millions of youngsters.

But those findings will arrive as the Omicron variant fades in the United States, complicating parental decisions about whether to vaccinate children.

Fewer than one in four children aged 5 to 11 are now fully vaccinated. More than half of adolescents 12 to 17 are fully vaccinated, but only about 12 percent have received a booster dose. Those percentages are even lower in rural areas of the United States.

Children are less likely to experience illness, so the balance of risk and benefit was never the same as for adults. And by now, as much as 95 percent of the country has some degree of protection from the virus because of vaccines or prior infection, according to recent data from the C.D.C.

Experts worry that the most recent findings have made it even more challenging to persuade some parents to immunize their children.

“We should be disappointed with the data — we wish it could be better,” said Luciana Borio, a former acting chief scientist at the Food and Drug Administration. “But in the near term, it’s important for parents to still vaccinate children.”

The country may still see a surge in the fall or winter, and the best protection for children will be to have had at least two shots before then, she said.

The vaccines are continuing to prevent severe disease and death, even with the Omicron variant. That trend is particularly clear at hospitals, said Dr. James Campbell, a physician at the University of Maryland School of Medicine and a member of the American Academy of Pediatrics committee on infectious diseases.

Among his pediatric patients who were sick enough to need a mechanical ventilator or die, “every single one of them was unvaccinated,” Dr. Campbell said.

A Dosing Conundrum

The recent studies suggest that the problem is not so much the vaccine as the dose.

In the trials in adults in 2020, vaccine manufacturers made best guesses at the right dose and opted for short intervals between the shots to protect people as quickly as possible during the initial surge.

The Pfizer-BioNTech and Moderna vaccines proved to be safe and powerfully protective in clinical trials and were speedily authorized for use. But the trials in children were complicated by the arrival of the Delta and Omicron variants, and the vaccine appeared to be less protective in children aged 2 to 4.

At the moment, the Pfizer-BioNTech vaccine is the only one authorized for children. (The vaccines made by Moderna and Johnson & Johnson are authorized only for adults.)

In the Pfizer trials, adolescents aged 12 to 17 were given 30 micrograms, the same dose given to adults. But children aged 5 to 11 received 10 micrograms, and those 6 months to 5 years old received just three micrograms.

These doses may have been too low to rouse an adequate and lasting response. But federal officials who have seen the data told The New York Times that higher doses produced too many fevers in children.

What to do when you can’t administer a dose high enough to shield children against the Omicron variant because of side effects? That’s the problem that scientists and federal officials are now wrestling with.

Pfizer and BioNTech are now testing a third dose in children under 12 to determine whether it can deliver the level of protection that two doses could not. The F.D.A. is still evaluating the Moderna vaccine for use in children 6 to 11. Last week, the agency rejected an application for authorization of the Indian-made vaccine Covaxin for children.

There are other Covid vaccines, like those made by Novavax and Sanofi, that may turn out to work well in children. Federal health officials should consider all of these options and test whether a different dose or a longer interval between doses would improve the immune response, experts said.

“It seems to me that vaccines for children are taking longer than they should, given the importance of protecting that population,” Dr. Borio said. “The sooner we re-energize our search for safe and effective vaccines for children, the better off we’ll be.”

Masks in Schools

The disappointing findings, along with the receding Omicron surge, have greatly complicated policy decisions for local health officials.

Countering Florida’s recommendations, Louisiana and California will require schoolchildren to be immunized by fall 2022, and the District of Columbia set a deadline of March 1 for students 12 and older to be fully vaccinated.

Other states may adopt similar policies but are likely to do so only if the F.D.A. grants the vaccine full approval for use in schoolchildren, said Hemi Tewarson, executive director at the National Academy for State Health Policy, a nonpartisan organization.

“For a lot of them, that’s going to be key for requiring vaccines as a mandate,” she said.

A school vaccine mandate would ease the fears of many families with children who have medical vulnerabilities.

Nearly every member of Heather Keever’s family, including her son, Wesley, 14, has heart disease, high blood pressure and kidney disease. But because they are not technically immunocompromised, they have not qualified for accommodations at work or at school, said Ms. Keever, 42, a consultant in suburban Chicago.

“They forget that there’s some of us who just literally can’t take the mask off,” at least until the rates fall much further, she said. “I felt like I didn’t matter and I wasn’t important and I was arguably disposable. And I still do.”

Some scientists, too, have said they would continue to wear masks until the numbers dip because of the risk of infection.

Because the youngest children have not yet been vaccinated, “I’d be very hesitant to ask a child below 5 to remove masks indoors,” said Akiko Iwasaki, an immunologist at Yale University who studies long Covid, the cluster of symptoms that can persist long after the acute infection is resolved.

Given the muddled results on the effectiveness of vaccines and the mixed messages on the benefits of masks, families are weighing risks on their own — and coming to very different conclusions.

Jennifer Steinberg, a management consultant in Wilmington, Del., has two daughters who split their time with her and their immunocompromised father.

“Yes, great, it protects against severe illness,” Ms. Steinberg said of the vaccine. “But if your kids are still going to get infected, this is a huge disruption to family lives. I’m probably going to stay masked for the foreseeable future.”

Katie Sunderland of Arlington, Va., has long been ready to give up masks. If her children, 7 and 5, do become infected, “that’s a trade-off I’m OK with if they are able to unmask and see faces,” she said.

“I’m not convinced that wearing a mask would significantly reduce the risk of getting Covid anyway — especially not the type of masks I see most kids wearing,” Ms. Sunderland, 37, said. “It doesn’t make sense to me to impede my kids’ development for that very, very, very low risk.”

But many other parents are still unsure of what to do. Ms. Gonzalez has a niece and nephew who have congenital heart defects and problems with lung capacity, and she will continue to wear masks to protect them, she said.

But if her son’s school drops the mask requirement, “we don’t know what we’re going do yet.”