Rapid decline of humoral response to two doses of BNT162b2 vaccine in patients with solid cancer after six months: The urgent need of the additional dose!

Abstract

Introduction: We previously reported on the immunogenicity and safety of BNT162b2 in a large cohort of patients with cancer after the first and second doses (Di Noia et al., 2021) [1]. Herein, we present result after six months of follow-up.

Methods: This prospective study included patients affected by solid tumors and afferent to our institution who received two doses of BNT162b2 vaccine. A cohort of vaccinated healthcare workers (HCW) was used as control-group. Both cohorts were evaluated for the titer of anti-Spike (S) IgG at prefixed time-points (TPs). Time-point 4 was scheduled at 24-26 weeks after the second dose.

Results: In the current analysis, 400 patients and 232 healthcare workers were evaluated. Responders (IgG > 15 AU/mL) in patients group were 86.5% compared with 94.4% among healthcare workers. Also the IgG titer at TP4 was significantly inferior in patients than in healthcare workers (70.81 vs 134.64 AU/ml, p < 0.001). There was a more rapid decline of the antibody level from TP3 to TP4 in patients than in healthcare workers (1.78 vs 1.3 fold). The estimated IgG half-life was significantly shorter for patients (73 days) than in healthcare workers (118 days) as well as the time to reach negative serological status (340 vs 532 days).

Conclusion: The decline of humoral response to the vaccine observed in patients with solid cancer after six months from the first dose support the urgent need of an early additional dose.

Keywords: BNT162b2 vaccine; COVID-19; Patients with cancer.