As schools prepare to open for a third straight pandemic-strained year, about half of parents are holding off on coronavirus vaccinations for their children, taking a wait-and-see attitude or, for many, outright opposing the shots, a new survey finds.

The Kaiser Family Foundation poll finds significant barriers to increasing vaccination among children ages 12 to 17, who have the lowest rates of any age group at 41 percent. Large shares of parents of unvaccinated children say they fear the long-term effects of the vaccine as well as serious side effects. Many parents who are vaccinated are still holding off on inoculating their children, the survey found.

But the survey also has some cause for optimism, suggesting that more people would seek out vaccines if they were offered by a trusted source and if they realized they were free.

“We see a lot of levers that could be pulled, both to give parents more confidence and more information and also make if it is easier and more convenient and more financially feasible to get their kids vaccinated,” said Liz Hamel, director of public opinion and survey research for the Kaiser Family Foundation.

Coronavirus cases have been surging across the country, driven by the highly contagious delta variant, increasing the urgency of vaccination.

The Kaiser Family Foundation survey also found significant opposition to schools mandating the vaccines for children ages 12-17, the group now eligible for the shots under emergency Food and Drug Administration authorization. Nearly 6 in 10 parents oppose a mandate attend in-person classes. Support for school vaccine mandates was not much, if any, higher even if the FDA were to grant full approval for the vaccine.

In both cases there were significant partisan divides, with about two-thirds of Democratic parents favoring such mandates and more than three-quarters of Republican parents opposing them.

There were similar partisan divides over mask requirements, but overall support for these mandates was higher. Sixty-three percent of parents with school-age children said their local school should require unvaccinated students and staff to wear masks. Support was at 88 percent among Democrats versus 31 percent among Republicans. Not surprisingly, decisions about mask rules for the fall are being colored by partisanship, with several GOP governors prohibiting districts from imposing mask requirements and some Democrats requiring them statewide.

The survey found 41 percent of parents of children ages 12-17 said their child had been vaccinated, up from 34 percent in June. Another 6 percent said their child would get the vaccine right away.

Almost 1 in 4 said they were taking a “wait and see” approach to see how the vaccine works for others, and 9 percent said they would get their children the shot only if their school requires it. Few schools are doing so now, but that could change if and when the FDA grants full approval. For now, most educators are hoping that persuasion and efforts to make the vaccine more available will raise the rates.

One in 5 parents said their children will definitely not get vaccinated.

Nearly 9 in 10 parents of children who are eligible but not vaccinated said they were very or somewhat concerned about the long-term effects of the vaccine in children. Nearly 8 in 10 noted worry about serious side effects. And almost 3 in 4 said they worry that the vaccine could negatively impact their child’s fertility. Concerns about fertility have been rampant even though the Centers for Disease Control and Prevention says there is no evidence that any vaccine causes these problems.

Addressing those fears is complicated. The best bet may be pediatricians, who the report found to be the most trusted source for vaccine information. The survey found more than three-quarters of parents trust their child’s pediatrician a great deal or a fair amount.

Other barriers to vaccination may be easier to mount, though they are less prevalent. About one-third of parents are concerned about taking time off work to get a child vaccinated and recover from any side effects. More than a third of Hispanic and almost as many Black parents worry about the cost, even though the vaccines are supposed to be available free.

The survey was conducted from July 15 to Aug. 2 among 1,259 parents with a child under age 18 in their household. Interviews were conducted in English and Spanish online and by telephone. The margin of sampling error is plus or minus four percentage points for the full sample and plus or minus five percentage points for parents of children ages 12-17.