Eliakim-Raz N, Leibovici-Weisman Y, Stemmer A, et al. - In adults aged 60 years and older, a third BNT162b2 (SARS-CoV-2 vaccine) dose was found to be linked with significantly elevated IgG titers after 10 to 19 days, with no major adverse events.

• Participants were individuals aged 60 years and older (n=97; median age 70 years (IQR, 67-74), 61% women) in whom antispike (anti-S) IgG antibody titers were assessed before and after a third BNT162b2 dose.

• Prior to the third dose (median, 221 days [IQR, 218-225] after the first vaccination), seropositivity was evident in 94 participants (97%).

• Post-third dose, significant rise in median titer level was seen, from a median of 440 AU/mL (IQR, 294-923) to 25 468 AU/mL (IQR, 14 203-36 618), and all participants became seropositive.

• Among kidney transplant recipients who did not respond after 2 vaccine doses, 49% became seropositive after a third dose of the SARS-CoV-2 mRNA-1273 vaccine (Moderna), though this observation cannot be generalized to older adults.

• This research adds serologic data to the clinical data on response to a third dose in adults aged 60 years or older.