Eligible patients can schedule a vaccine appointment.
Both Pfizer and Moderna are researching how their vaccines work in children as young as 6 months.
In the meantime, infectious-disease experts say not to.
All four trials combined included 23,848 participants.
Clinical trials of the AstraZeneca vaccine are also underway in the United States, Peru, and Chile.
Pfizer trial recipients also reported a bit more swelling lymphadenopathy after their boosts.