Originally published in Bloomberg Businessweek on February 9, 2021.

Joe Biden pledged in early December to reopen most U.S. school buildings within his first 100 days as president: “It should be a national priority to get our kids back into school and keep them in school,” he said. Soon after, however, he narrowed that goal to a majority of elementary and middle—rather than all K-12—schools. And on Jan. 28, Anthony Fauci, Biden’s chief medical adviser, warned that meeting even that lower target “may not happen.”

Technically, in fact, it may have happened already. There’s no comprehensive list of nationwide school reopenings. But according to a tracker by Burbio, a company that specializes in aggregating school calendars, more than half of the 53 million K-12 students in the U.S. had access to some in-person learning during the first week of February, and the number of students attending virtual-only schools trended down throughout January.

A reopened school isn’t necessarily one where all students learn in person five days a week; many students are likely to shift to a hybrid schedule with a mix of online and in-person learning, as millions of kids have so far. The arrangement is often necessary to keep class sizes small enough to meet social distancing requirements and prevent the coronavirus’s spread. Other students could opt to stay virtual full-time if their families have the choice.

Although the White House can work with industry to ramp up vaccine production and mobilize federal agencies such as the Federal Emergency Management Agency to help distribute it, school decisions ultimately rest at the state and local level.

Political leaders want more schools reopened not just to aid the economic recovery but also to provide much needed relief to students and families. Douglas Harris, the director of the National Center for Research on Education Access and Choice at Tulane University, warns of learning loss, mental illness, child abuse, and malnutrition resulting from keeping schools closed.

“Aside from their parents, there’s nothing children depend on more than their schools,” Harris says. Where it’s safe to do so, he adds, “it’s important to give students the option of in-person instruction as soon as possible.”

Recent research indicates that it’s safe to reopen schools where community spread of the virus is low. There’s less agreement on whether that’s the case where spread is higher. Some experts say it could still be safe to reopen as long as infection controls are in place. Rates of spread tend to be lower in younger grades than in high school, possibly because it’s harder to enforce social distancing with teens.

The vaccine rollout should help hasten reopenings, but supply chain challenges suggest it will take weeks, if not months, to inoculate educators. (There are no vaccines approved for children under 16 yet.) Districts are grappling with whether to require staff to return before getting vaccinated, and sometimes meeting opposition from teachers unions—most notably in Chicago, the nation’s third-largest district, which narrowly avoided a teachers’ strike in the first days of February.

In Ohio, teacher vaccinations have begun, but Republican Governor Mike DeWine acknowledged it’s unlikely that staff will have been fully vaccinated by March 1, the statewide reopening deadline he has set for all schools. (Forty-six percent of Ohio students were already attending school in person full-time as of Jan. 28, according to data DeWine shared.) Teachers union presidents for Ohio’s eight urban school districts protested that DeWine has pegged teacher vaccinations to schools committing to reopen, accusing him of using vaccines as a “bargaining chip.”

In California, Democratic Governor Gavin Newsom’s plan to give money to schools to reopen has sparked opposition from administrators as well as teachers. Los Angeles Unified School District superintendent Austin Beutner said in a statement that it “falls well short of what’s needed to help our schools” and that local case numbers remain “dangerously high.” Beutner reiterated that infection rates were too high for reopening after an L.A. councilman threatened to bring a lawsuit on Feb. 4.

Randi Weingarten, president of the American Federation of Teachers, a national union, would not directly say if all teachers should be fully vaccinated before reopening schools, but says the AFT is pushing to “align vaccine availability with school openings.”

Biden has suggested educators could return to classrooms without the vaccine if schools do regular on-site testing, take sufficient sanitation measures, and upgrade their ventilation systems. That position is endorsed by some public health experts, including those at the Children’s Hospital of Philadelphia (CHOP), which has been advising school districts in southeastern Pennsylvania through the pandemic. Amid a virus surge in November, CHOP urged all schools to remain virtual; it now says reopenings can be done safely, particularly with rapid testing regimes in place.

On his second day in office, Biden signed an executive order directing the U.S. Department of Education and the U.S. Department of Health and Human Services to provide clear guidance on masks, testing, and cleaning, and to create a clearinghouse of best practices from schools across the country. The president’s Covid relief plan calls on Congress to allocate at least $130 billion in dedicated funding for schools, and $350 billion in flexible state and local funding could help school districts avoid layoffs and plug budget holes that might hobble their reopening efforts. Republicans in Congress offered $20 billion to schools in a recent counterproposal.

As Biden offers the carrot of funding, state and local politicians are using sticks to try to get schools open again. In South Carolina, the state board of education has threatened to revoke teachers’ licenses for up to a year unless they return to classrooms. Maryland’s Republican governor, Larry Hogan, said that his administration will “explore every legal avenue at our disposal” to reopen schools by March 1.

Experts predict that the negative academic effects of closures will fall disproportionately on low-income Black and Latino children. But racial disparities are also likely to persist in the return to the classroom. A recent survey found that parents of Black students were 19 percentage points less likely than White parents to choose to a fully in-person option when it was available to them and that parents of Hispanic students were eight percentage points less likely. Among communities where the virus has taken a heavy toll, where schools have the fewest resources, and where access to high-quality health care is least guaranteed, many families think the risk of infection is just too great.

Among schools that have reopened, some, like New York City’s, are randomly testing staff and students weekly to monitor asymptomatic spread; other schools are prioritizing tests for those more likely to have been exposed to the virus, such as students participating in indoor sports. Some are finding that staffing is a challenge. Subs are in short supply, and educators who quarantine because of exposure or sickness can leave schools in the lurch and make social distancing more difficult.

Success Academy, New York City’s largest charter school network, announced in January it will remain remote for the rest of the school year, primarily to avoid the disruption of closing and reopening buildings, often on short notice. At the time of the charter network’s announcement, more than 300 public schools in New York City that had reopened were shuttered again because of Covid-19 cases.

Even if Biden makes good on his 100-day pledge, reopenings are likely to be fairly bumpy through the spring—especially if more contagious strains of the virus take hold. For many American families, it’s unlikely to feel like success.