A new review of safety data by the Centers for Disease Control and Prevention found just two incidents of serious adverse events following the nearly 1 million updated COVID-19 booster shots administered to children ages 5-11 since October.

The study, which was published Thursday by the CDC, examined more than 900 reports to the Vaccine Adverse Event Reporting System and found that about 99.8% of submissions for children ages 5-11 years were deemed not serious. Most of the reports were related to vaccination errors, like children receiving the wrong dose for their age. The two serious events reported included one child who developed symptoms consistent with Miller Fisher syndrome, which is a rare neurological condition that is considered to be a variant of Guillain-Barré syndrome, and another child who was hospitalized with hives and arthritis.

Researchers also looked at more than 3,200 submissions to v-safe, a safety surveillance system established by CDC to monitor adverse events after COVID-19 vaccination, and found that no children enrolled in the program received hospital care after vaccination with the updated shot. Additionally, no incidents of myocarditis or death were reported after the shot. “Preliminary safety findings from the first 11 weeks of bivalent booster vaccination among children aged 5-11 years are reassuring,” the study said.

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