Background/Aim: To prospectively evaluate the efficacy and safety of the BNT162b2 vaccine in solid cancer patients undergoing systemic chemotherapy (n=63). Patients and Methods: COVID-19 anti-spike protein antibody levels were measured before the first BNT162b2 vaccination, just before the second BNT162b2 vaccination, one month after the second BNT162b2 vaccination, and 3 months after the second BNT162b2 vaccination. Anti-spike protein antibody seropositivity was set at ≥0.8 U/ml. Results: Colorectal cancer was the most commonly observed primary disease (36.5%). ECOG-PS 0 was observed in the majority (52.4%) of patients. The overall response rate and the median (range) anti-spike protein antibody levels in the whole cohort at 3 months after the second BNT162b2 vaccination were 98.4% (62/63) and 206 (0.4-3,813) U/ml. None of the patients required postponement or discontinuation of systemic chemotherapy because of an adverse reaction. Conclusion: The BNT162b vaccine in solid cancer patients undergoing systemic chemotherapy is effective and safe.
