It’s official: Teens are getting the shot. Today, the US Food and Drug Administration decided that Pfizer’s Covid-19 vaccine could be used in children as young as 12, following a clinical trial that found the vaccine was safe and effective. The decision means roughly 17 million children younger than 16—the previous cut-off for the Pfizer shot—are newly eligible for vaccinations, which could begin as soon as Wednesday, following a separate recommendation from a CDC panel.

sanitation workers cleaning stairs

When she first had heard about the trial results, Monica Gandhi, an infectious disease expert at the University of California, San Francisco, was relieved. The opportunity to vaccinate teens had come sooner than expected and, as she saw it, in the nick of time: It meant plenty of breathing room to start vaccinations before the fall. More than half of California students are learning remotely, according to an analysis by the education nonprofit EdSource, and the next semester remains uncertain. But with vaccines available, the process of getting everyone back on campus was looking smoother—for reasons that, in her view, had more to do with psychology than with epidemiology. “It’s been such a barrier for middle and high school students—not because schools aren’t safe, but because of the perception that they aren’t,” she says.

Across the US, the return to school has been complicated by a twist-filled pandemic spring. First there was the problem of high case rates—too much virus was moving around during the winter surge, just as district officials from New York to Los Angeles were debating how to return more students to in-person instruction. Then came the unknowns of new, more transmissible variants. But even in places where case rates are now far below those winter peaks, and where teachers have been vaccine-eligible for weeks, the prospect of returning has remained fraught. Some parents are reluctant to send their kids, who may now be the only unprotected people in their families, to mix with other unvaccinated people. And some teachers are wary of receiving those students in their classrooms.

In San Francisco, where Gandhi lives, some students have returned to campus, but often only to open their laptops again when they arrive—so-called “Zoom in a room,” as disgruntled parents have put it. Schools are constrained by CDC recommendations of three to six foot distancing in buildings, and by limited staffing due to teachers with medical exemptions. This summer, state legislators will decide whether to continue a waiver that has allowed remote instruction. Laura Dudnick, a spokesperson for the San Francisco Unified School District, notes that the district’s agreement with employees covers only the remainder of the spring semester, and says it will follow public health guidance as it develops plans for the fall.

Meanwhile, public health experts like Gandhi have maintained that schools can be fully opened safely, even prior to widespread vaccination. The benefits of doing so would be enormous, she says, given the toll of closures on mental health and learning. It’s a tricky needle to thread: As more schools have opened, we’ve learned that kids do transmit the virus—perhaps more than scientists initially thought—and some studies have linked the reopening of schools to more household infections. But we’ve also learned how to manage those risks better with precautions like good ventilation, masks, and testing. A recent preprint by Johns Hopkins University researchers, which has not yet been peer-reviewed, found that the risk that kids attending in-person school would seed infections in their households disappeared in places that adopted careful protection measures. (The research was conducted prior to widespread adult vaccinations, which should further reduce household spread.) A January review by CDC scientists came to a similar conclusion, based on data from a number of countries where schools had by then reopened. School outbreaks did occur, they found, but they were easier to control than outbreaks in places like nursing homes.