CDK4 and cancer: Our univariate analysis indicated that currently undergoing another therapy during the collection of blood samples (such as chemotherapy, chemotherapy plus radiotherapy, endocrine therapy plus abemaciclib to inhibit CDK4/6, and Chinese medicine), and other treatments during the second vaccination (such as chemotherapy, pertuzumab, and trastuzumab for HER2-positive cancer, and chemotherapy, pertuzumab and trastuzumab for HER2-positive cancer) were related to undetectable NAbs against the SARS-CoV-2 wild-type virus after two doses.