Several coronavirus vaccines are under development in the U.S., and many of them are undergoing human trials with the hopes of knowing their effectiveness by the end of 2020 or early next year. But those trials only involve adults, so they can't determine the effectiveness and safety of the vaccines when they're used on children. So while American adults are expected to have access to COVID-19 vaccines by next summer, children won't get theirs until the 2021 school year. The New York Times reports.

As the Times describes, "many vaccines — including ones for measles, polio, and tetanus — were designed from the outset to be given to children." Developers usually start testing those vaccines on adults, and then if they show no serious side effects, work their way down to younger ages and adjust dosages along the way.

Coronavirus vaccine developers were expected to follow this same process, especially after many adult trials over the summer showed no serious side effects. "But that did not happen. And with autumn around the corner, that still hasn’t happened," the Times writes. At this point, it may take up to a year to get coronavirus vaccines prepared for children. Read more about the COVID-19 vaccine development process at The New York Times.