Everyone involved has some control—but not full control—over how long it’s all going to take. A Pfizer spokesperson told me that the company plans to submit an EUA application for the 5-to-11-year-old group “by the end of September,” and for the six-month-to-5-year-old group “shortly thereafter.” Then the FDA will take the reins. After this article was published, a Moderna spokesperson told me that the company’s full data set will likely be ready “later this year or towards the very beginning of 2022,” and that information on different age subgroups might be available at different (as yet unspecified) times.

The FDA has been saying since May that it expects vaccines to be available for kids under 12 on a “fall or winter timeline.” But it hasn’t offered much in the way of updates. When I asked the agency for its best estimate of when it might issue an emergency-use authorization for either the Pfizer or Moderna shots in young kids, a spokesperson referred me to comments that the director of the agency’s Center for Biologics Evaluation and Research made in early July indicating that he expected results from the clinical trials “later this year.”

As we get closer to that amorphous deadline, you can keep an eye out for signs of progress. The first milestone will come when the clinical trials in vaccines for kids stop accepting new participants.