A 13-year-old Michigan boy who died in his sleep three days after getting a second dose of a COVID-19 vaccine had a systemic bacterial infection that caused his death, according to an investigation by the U.S. Centers for Disease Control and Prevention.

Jacob Clynick's family discovered the boy on June 16, 2021, in the bedroom of his Zilwaukee home in Saginaw County, Michigan. He'd gone to sleep the night before complaining of flu-like symptoms and a slight stomachache, and never woke up.