An investigation has been launched into the death of the 13-year-old Michigan boy who died in his sleep days after getting his second dose of the Pfizer COVID-19 vaccine by the US Centers for Disease Control and Prevention, according to US media reports.

On June 13, Jacob Clynick, who had just completed eighth grade, received his second dose of the Pfizer jab at a Walgreens vaccination site. Following which he died on the evening of June 15.

While an autopsy is being conducted by the Saginaw County Health Department, CDC officials said a probe has been launched to determine whether the boy’s death was related to the vaccine shot.

“Meanwhile, the health department continues to encourage families to speak with their physicians to weigh their own risks and benefits of vaccination,” Saginaw County Health Department Medical Director Dr Delicia Pruitt and Health Officer Christina Harrington said in a joint statement, according to Detroit Free Press. 

Additionally, Martha Sharan, a spokeswoman for the CDC, acknowledged the investigation in a statement, saying, “CDC is aware of a 13-year-old boy in Michigan who died after receiving a COVID-19 vaccination.”

However, she warned that the case is still under investigation and until it is complete, “it is premature to assign a specific cause of death,” according to ABC News.

Following the death, Tammy Burages, aunt of the deceased boy, said that Clynick had complained of the common symptoms, like fever and fatigue, after receiving the vaccine. But on the night of his death, he also complained about a stomach ache. 

Also read: Should fully vaccinated people wear masks? Read what WHO has to say

According to media reports, a preliminary autopsy found evidence suggesting that Clynick’s heart was enlarged when he died. While Burages also claimed that a medical examiner found fluid around the organ.

The death of the boy comes following a CDC advisory committee’s acknowledgement of “a likely association” between the Pfizer and Moderna COVID-19 vaccines and the risk of heart problems in adolescents and young adults, according to reports from USA Today.