A strong, cell-mediated immune response entailing helper T1 cell–biased CD4+ and CD8+ lymphocytes elicited by the BNT162b1 vaccine has been reported, yet the cellular mechanism remains to be elucidated.18 Findings from implementation of other vaccines in immunosuppressed populations indicated that inactivated influenza vaccines are safe in immunocompromised patients, although a trend toward an impaired humoral vaccine was observed. Here, CD4 is linked to influenza.