Reuters exclusively reported in January that Kennedy played an instrumental role in organizing mass litigation against Merck over its human papillomavirus shot Gardasil.
In his additional responses to the Finance Committee, Kennedy wrote he would not commit to recuse himself from various HHS matters related to the Gardasil vaccine, including public statements related to Gardasil.
Kennedy, who founded the anti-vaccine group Children's Health Defense, argues that he is not against vaccines. The group has sued in state and federal courts over vaccines.
Senator Cassidy, a key Republican senator on the Finance Committee, told Kennedy last week he was struggling with the nomination, saying he had reservations about Kennedy's "misleading arguments" on vaccines.