President Biden's goal is to reopen all schools, but will it happen this year?

President Joe Biden has made safely reopening all schools one of his goals in the first 100 days of his administration, but it comes during a time when there is a national vaccine shortage and children are not yet eligible for inoculation.

On Long Island, some education leaders have said schools likely won't return to full-time, in-person learning this school year because of COVID-19 concerns. The Biden administration, facing criticism from parents who want their kids back full time and pushback from teachers' unions about school safety, is relying on recommendations from the Centers for Disease Control and Prevention on how to safely reopen.

Local districts are gradually adding more in-person learning days, but there continues to be periodic closures due to positive test results from students and staff. Most recently, Plainview-Old Bethpage had an outbreak in a third-grade classroom, where 12 people tested positive for the virus. Additionally, some Nassau and Suffolk high-risk high school sports teams had to pause activities last week because of either positive COVID-19 tests or contact tracing.

Most high school students are not yet eligible to receive the vaccine by state guidelines. The U.S. Food and Drug Administration authorized the Pfizer-BioNTech vaccine for anyone 16 and older, but only kids 16 and older who are in another category, such as some types of essential workers, can currently get it in New York. Health experts said it likely will be at least the summer until children ages 12 to 15 can obtain a vaccine, and until 2022 when younger kids can get it.

Clinical vaccine trials studying children under 12 have not yet begun, and Pfizer did not finish enrolling kids ages 12 to 15 in such trials until last month. Drug companies traditionally study vaccines and other pharmaceuticals in stages, conducting research on older kids before they study younger ones.

CDC director Rochelle Walensky said Sunday that schools nationwide need "a lot more resources in order to get safe" enough to reopen, including more space, staffing and nurses and better ventilation systems.

"I think that there's a lot of work that we need to do in order to get our children, (make) our schools a safer environment," she told Fox News Sunday.

Some Long Island teachers have been able to get shots, but mass vaccinations for school staff remain rare due to the scarcity of the vaccine. Still, some educators are trying to work in more in-person days.

Superintendent Donald James said seniors at Commack High School were allowed this month to start going to school on their remote days, when they can do "any number of things," including remote class assignments or school projects.

Seniors had been in-person every other day since September. They now can sign up to come daily, and attend their remote classes from the library.

James said his district's positivity rates are low. The western Suffolk K-12 district has had 240 total positive cases since the start of the school year, including 110 at the high school, where about 1,270 students and staff are on-site daily, according to state data as of Feb. 8.

James said he hopes social distancing rules will ease up soon, so more students can return.

"The challenge for all schools is that you have to be six feet apart," he said. "We would like to see that regulation change. Some people might say that’s not safe. What we’re seeing in schools is that it is safe with the desk barriers, the masks and disinfecting the buildings every day."

Last month, the CDC published a study that stated schools are safe from virus transmission so long as mitigation measures are enforced, such as universal mask-wearing, physical distance in classrooms and common areas, proper room air ventilation, and testing to quickly identify asymptomatic-infected individuals.

The CDC in its recommendations on Friday reiterated the same strategies, adding that vaccination of teachers, while important, is not a requirement for reopening. The agency cannot force schools to reopen, and agency officials were careful to say they are not calling for a mandate that all U.S. schools reopen.

Andy Pallotta, president of New York State United Teachers union, said in a statement Friday that the CDC "confirms what New York educators have been saying all along. We all believe students learn best in classrooms, but that must be done in the safest way possible.

"Masks must be mandatory, there should be six feet of social distancing, schools need adequate ventilation systems, and hygiene protocols must be strictly followed. These are the steps that help build confidence in local reopening plans."

The Biden administration also has included $130 billion for school reopenings in the stimulus bill that is working its way through Congress.

With Rachelle Blidner, Joie Tyrrell and AP