Eliakim-Raz N, Massarweh, Stemmer A, et al. - A prospective cohort study evaluating the antispike (anti-S) IgG antibody response to the SARS-CoV-2 BNT162b2 messenger RNA (mRNA) vaccine (BioNTech-Pfizer) revealed seropositivity in 90% of the patients with cancer (90/102) and 100% of the healthy controls (78/78) after a median of around 5.5 weeks from the second vaccine dose. Significantly lower median IgG titer was recorded in the patients vs controls (1,931 (interquartile range [IQR], 509-4,386) AU/mL vs 7,160 (IQR, 3129-11241) AU/mL). Approximately 4 months after the second vaccine dose, the seropositivity rate remained high (87%) among the patients with cancer. Over time, there was a decrease in the median IgG titer in the patients and the controls.

• Evaluation of the IgG titers by tumor type and anticancer treatment indicated a 3.6-fold range in median titer values across tumor types and a wider range (8.8-fold) across treatment types.

• Immunotherapy plus chemotherapy/biological therapy linked with the lowest titers.

• Treatment with chemotherapy plus immunotherapy and immunotherapy plus biological therapy was the only variable significantly linked with lower IgG titers.

• A significant negative linear correlation was observed for the patients and the controls when the IgG titer was evaluated as a function of the time between the second vaccine dose and the blood sample drawn from each patient.