U.S. FDA Headquarters. Reuters Yonhap News

The U.S. Food and Drug Administration (FDA) is investigating a potential link between COVID-19 vaccines and deaths in adults, Bloomberg reported on the 9th (local time).

Bloomberg stated that the FDA has launched a broader investigation into the safety of COVID-19 vaccines.

The agency previously focused primarily on the impact of vaccines on children, but this time, the scope has been expanded to include adults, Bloomberg noted.

In a statement sent to Bloomberg, an FDA spokesperson said, "We are conducting a thorough investigation into deaths potentially related to COVID vaccines across multiple age groups."

According to Bloomberg, Dr. Vinay Prasad, head of the FDA's Office of Vaccines Research and Review, informed staff in an internal memo last month that stricter criteria would be applied to vaccine approvals.

Subsequently, 12 former heads of the FDA expressed concerns in an article published in the New England Journal of Medicine (NEJM), stating that this action "undermines the regulatory model designed to ensure vaccine safety, efficacy, and availability."

Previously, Robert F. Kennedy Jr., Secretary of Health and Human Services, had raised questions about the safety and effectiveness of COVID-19 vaccines and had also canceled hundreds of millions of dollars in funding for the development of messenger ribonucleic acid (mRNA) vaccines, the platform technology used by Moderna and Pfizer for their COVID-19 vaccines.

mRNA vaccines are developed using mRNA, which carries the genetic information of a virus. Vaccines based on mRNA technology are complex to develop but have the advantage of being able to quickly respond to mutations by simply swapping out the virus's genetic information once they are developed.