(1) Background: Children and young adults with
cancer are poorly represented in
COVID-19 vaccination studies, and long-term protection conferred by vaccination is not known. (2) Objectives: 1. To determine the adverse effects associated with
BNT162B2 vaccination in children and young adults with
cancer. 2. To assess its efficacy in stimulating immunological response and in preventing severe
COVID-19 disease. (3) Methods: Retrospective single-center study evaluating patients aged 8 to 22 years, with
cancer, who underwent vaccination from January 2021 to June 2022. ELISA serologies and serum neutralization were collected monthly from the first injection. Serologies below 26 were considered negative, while those above 264 BAU/mL were considered positive and indicative of protection.
Antibodies titers were considered positive above 20. Data on adverse events and
infections were collected. (4) Results: 38 patients were included (M/F = 1.7, median age 16 years), of whom 63% had a localized
tumor and 76% were undergoing treatment at the time of the first vaccination. Two or three
vaccine injections were administered in 90% of patients. Adverse events were mainly systemic and not severe, except for seven grade 3 toxicities. Four
cancer-related deaths were reported. Median serology was negative the month following the first vaccination and became protective during the third month. At 3 and 12 months, median serology was 1778 and 6437 BAU/mL, respectively. Serum neutralization was positive in 97% of the patients.
COVID-19 infection occurred despite vaccination in 18%; all were mild forms. (5) Conclusions: In children and young adults with
cancer, vaccination was well tolerated and conferred effective serum neutralization.
COVID-19 infections were mild, and
vaccine seroconversion persisted after 12 months in most patients. The value of additional vaccination should be further established.