The U.S. Food and Drug Administration is investigating deaths "across multiple age groups" that are potentially linked to COVID-19 vaccination, according to the Department of Health and Human Services.

"FDA is doing a thorough investigation, across multiple age groups, of deaths potentially related to COVID vaccines," HHS spokesperson Andrew Nixon told Agence France-Presse on Tuesday.

Initially, the review focused on possible child deaths, which FDA Commissioner Dr. Marty Makary announced in September.

Last month, a leaked memo from a senior FDA official claimed COVID vaccines have been linked to at least 10 infant deaths, reportedly without citing evidence.